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Seth Baumgartner and Jason Van Leuven open the mics for your crop steering and cultivation questions.
Seth [00:00:03]:
All right.
Kaisha [00:00:03]:
What's up, gromies? Welcome to AROYA Office Hours, your source for free cannabis cultivation education. I'm your moderator, Kaisha. We are on episode 108, shout out to our live viewers on YouTube and Instagram. We're trying a little something new right now. Hope you all can see us. And to everyone tapping in on Spotify, Apple Music, YouTube, or wherever you listen to your podcast. Thank you so much for your support. And if you like the pod, please do drop us a review.
Kaisha [00:00:27]:
We appreciate your feedback. Seth, Jason, welcome back to the studio. Guys. How are you?
Jason [00:00:33]:
Good.
Kaisha [00:00:33]:
Good to see you. It's been a couple weeks and the gromies are dropping some great questions, so we're just going to get right to it. Someone dropped this question. They wrote, could you guys please settle a debate for me? I'm having a hard time convincing my superiors that we should be making our greenhouse environmental. Our environmental controls based off of temperature and BPD instead of temperature and relative humidity, as they believe relative humidity is a better metric for reducing botrytis. Could you guys give your thoughts on this and possibly elaborate on the pros and cons for both RH and VPD?
Jason [00:01:09]:
Yeah. So, um. Well, maybe we'll just start off with what I do. I like to look at temperature and VPD. So, you know, given my specific temperatures for certain phases, um, then I'll just hit. Try to hit an ideal VPD, which could be different for different phases as well. Right. When you start to raise that up as the plants get older and larger.
Jason [00:01:29]:
And, um, you know, VPD is using both temperature and humidity. Relative humidity. So the reason that I like using VPD to set my humidity, basically, is because then I can make sure that I have the appropriate relative humidity for that specific temperature. Right. So if my temperature changes, but my relative humidity doesn't, then my VPD is going to change. But we can change temperature and humidity and maintain the same VPD. So it's. It's really kind of all in the same.
Jason [00:02:00]:
It's just that we know we want a specific VPD so that, like, our temperature doesn't necessarily matter. We don't have to, you know, say okay for. Or, excuse me, our relative humidity doesn't matter. So we might be, rather than changing our relative humidity and knowing what our changes are, we can just shoot for a specific VPD. I didn't say that very well.
Seth [00:02:23]:
It's okay. I think let's just look at kind of what. Let's start with some definitions there. The vapor pressure deficit. We're looking at how hard the atmosphere is pulling on that plant and what kind of energy is available to drive transpiration. VPD is essentially a calculation made out of having, you know, temperature and relative humidity. You can use absolute humidity if you want to, not in place, but with a different equation. But what we're looking at is what, what is the environment actually doing to the plant? And part of the reason I like to use VPD is when I say relative humidity, I already just said relative.
Seth [00:02:54]:
Okay, so the actual meaning of that value is changing based on the temperature. So if I try to simplify it to just rh, that's a constant, constantly moving target based on what temperature I'm on. Now, if I go to VPD, that VPD calculation allows me to balance what my ideal humidity is at a given temperature in order to specifically avoid things like botrytis and aspergillus. You know, when we look at VPD, that's also a great measurement we can use to judge conditions for things like mold growth. You know, if I'm going. And when we're talking specifically about mold in the greenhouse, there's a few things to touch on. Number one, oftentimes seeing a lot of botrytis, sometimes some aspergillus. It's tough to eliminate that botrytis in most greenhouses because unless you've got HEPA filtration on your incoming air, somehow you're most likely pulling in Botrytis spores from the environment just around your grow.
Seth [00:03:50]:
But one thing we do know, and very easy to look up, is that between 55, 60 and 70 degrees, that's when things like Botrytis and Aspergillus like to grow best. That's their optimum survival range. Once we go over 70, they don't proliferate nearly as much. They don't grow as well. So when we're trying to ripen and go below 70, we're using that 1.0 VPD value as a minimum to say, hey, it's becoming too humid. And then another issue, especially in greenhouses, is really looking at that dew point factor. When you have lights off or curtains closed, when you shut that greenhouse down and it starts to get cool at night, especially if you're running wet walls or evaporative cooling. If there's a mold issue, hey, you might, you might need some more dehumidification capacity.
Seth [00:04:33]:
You might need to get it drier in there to run those temps, but you might also be accidentally raining on the plants. When we talk about greenhouses specifically, we've got a little bit more of a dynamic system. We've got a temperature gradient. We've got the outside temperature having much more of an impact on what's going on inside. And something as simple as it being cool in the spring or the winter or the fall, and suddenly dropping the temperature inside can cause condensation on the ceiling of the greenhouse. If that rolls off down onto our buds, a wet bud usually equals a moldy bud in a few days. So that's one thing to look out for. And I think, you know, there's resistance to using VPD just because traditionally that's not what our meters read out, right? So relative humidity seems very tangible because you're looking at that value every single day.
Seth [00:05:21]:
And if you've done that for 20 years, it feels more comfortable than VPD, which might seem very intangible, you know, and it kind of is, right? Like, if I'm looking at a temperature that says 80 degrees, I know what 80 degrees is. If I'm talking about relative humidity, I can only say, well, that's a percentage. So that means out of a hundred, this is where we're at. When I. Someone's new to the concept of VPD, especially, it's just, it's not very tangible, because they're not. Until you do that calculation over and over and over, or look at setting your system to achieve a certain VPD, your mind might not automatically go to, hey, uh, I'm trying to drop it to 65. What does my humidity needing to be in the last two weeks? The answer is like, 43% to 45%. Um, I know that because I've done that calculation a lot.
Seth [00:06:07]:
That gives me about a 1.1 to 1.3 vpd right in range, especially overnight. But if I hadn't looked at that chart and done that calculation a bunch of times, that wouldn't be my assumption. And if I was more, more familiar with thinking about it in terms of, hey, I'm looking at, you know, up to 75% humidity in my first three weeks, and then we're backing it off to 65, and then we're getting down to 55 and down into the forties at the end. That's really, like I said, it's tangible. I think it's more of a habituation thing than anyone having any major resistance. And at the end of the day, we're really talking about what's the temperature and how much water is in the air. If we wanted to get real weird with it, we'd only ever say a temperature and an absolute humidity. Right.
Seth [00:06:51]:
But unfortunately, absolute humidity is not a whole lot more tangible for anyone that's been thinking about relative humidity. Humidity for their whole life. Yeah.
Jason [00:06:59]:
And actually Aurora has a VPD chart. So I'm going to share my screen here and we'll check it out. So it's VPD. Arroya IO. And kind of as I was talking, as Seth was talking, one of the reasons we like using VPD is because let's say that we're shooting for 1.2 kpas, our VPD. And so we could say, all right, well, I know if I'm going to be. Maybe we're running some chilly nights and we've got an air temp at around 65 degrees. Well, I know now my relative humidity needs to be about 42%, but maybe for, for daytime I might be up in that.
Jason [00:07:47]:
Let's go to 75 degrees and I'm going to. We actually have this cool little tool here where it's. You can lock your air temp and your leaf temp at a specific offset. We're not going to run an offset, but let's say we want to be at say 75 degrees during the day. Well, now we can't stay at that consistent 42% humidity. We can still be at a nice 1.2 kilopascals for our VPD, but we're going to need to adjust our relative humidity to about 60%. Right. So we could say, hey, we need to be at 1.2 for our VPD and that can be kind of consistent.
Jason [00:08:20]:
Whereas if we're changing our temperatures, you're going to have to change your relative humidity as well in order to achieve that. That consistent VPD.
Seth [00:08:28]:
Yeah. And part of the reason we want that consistency is the way the plant responds to that VPD is by adjusting how open its stomata are. So if our VPD is going up and down and up and down throughout the day, that's we've got loss of efficiency right there because the plants putting energy towards responding to that changing stimulus rather than just staying stomataly open and growing and then going into the nighttime, we still want a certain amount of transpiration happening. It's a little different than the daytime because we don't. The plant's actually using energy to transpire at night. So we also want to keep that VPD up a little bit to optimize that and also have a very predictable dryback rate. And alternatively to nighttime transpiration is important for plant nutrition. So if, let's say we're able to maintain VPD all day, but then nighttime comes around and hey, we can't keep it above one.
Seth [00:09:18]:
We're keeping it, you know, like 0.4 in a really bad scenario. In that case, your plants just. You may not have horrible plant health issues, but your plants are never going to be running at 100%. They're never going to get as big as they could. For the same reason. If you put a tomato in the yard and only water it half as much as the one next to it, the smaller one will still survive. You'll get less tomatoes. Right.
Seth [00:09:40]:
We've got a limiting factor we've introduced.
Jason [00:09:43]:
Yeah. And there's lots of charts online. I did just draw a relationship between still model conductance is on our y axis here, and then vapor pressure deficit across the bottom. And what we're trying to do is optimize stomatal conductance because that means that our photosynthetic rate can be maximized. That's allowing the most carbon exchange, which is obviously one of the main building blocks in our plants. They got to suck that up out of the air in order to make plant food and become bigger plants. So we always want to optimize that for the most part, with cannabis, you know, we're trying to shoot for about a 1.2 through the bulk of flour. So typically after.
Jason [00:10:25]:
After about weeks, two or three, we like to be up to that 1.2 kilopascals, and that's going to allow the most gas exchange, our small conductance. So our stomates are as open as possible. Yep.
Seth [00:10:39]:
Yeah. I mean, I think it's important to highlight, too. You know, we spend a lot of time talking about things being way too humid and damp. There is, you know, once you go above that 1.6 or so range in VPD, we do start to see that more of an extreme drought or heat stress that the plant gets. So you really don't. There is a sweet spot. There absolutely is. And then another thing to remember, too.
Seth [00:11:00]:
Part of the reason we have that leaf temp option on the VPD calculator is, at the end of the day, we're measuring everything around the plant, but we can only get that sensor so close to the actual leaf surface, and that tiny area is what we care about. So there are times that you really do want to take that leaf surface temp into account and make sure that, like, hey, maybe my, you know, like, let's just talk about HPS for a second. I've seen many situations where, hey, our ambient VPD, the climate's great in the room, but if I go around with thermometer and start mapping out heat on some plants, I'll actually have parts of different plants. Anything that sticks up above a certain level will have an insanely high leaf VPD on the surface of that part of the plant. And that's where you'll see some plants that look, you know, a little more bleached or beat up or have a little bit different leaf formation that are taller versus just a foot farther down in the canopy. Not just even size wise, but also just different levels of plant stress that you can see, especially if it's been going on a long time. Start to see in that leaf morphology, too.
Jason [00:12:00]:
Yeah, we've gotten this question quite a few times on the episode about Leaf VPD versus Air VPD. And for the most part, we look at air VPD because it's what we can control and it's easier to measure. Like Seth said, leaf VPD is actually the important value there. But what, you know, what are the things that we can use to adjust leaf VPD? Well, that's air VPD. Right. And so that's kind of why that is the rolling measurement that we're typically looking at. Leaf EPD. Yeah, you can take a lot of samples with infrared thermometer, and those samples can be kind of a lot of work.
Jason [00:12:42]:
So, you know, the more of those samples, the better accuracy you can get. Just like Seth said, there's going to be a pretty big range of what those leaf vpds look like or those leaf temps that cause that VPD. Um, and so that's kind of just the breakdown as far as, uh, why we look at air VPD. Yeah.
Seth [00:12:58]:
I think another thing, too, to bring in here is like, when we are looking at VPD in general, a big thing we're trying to do, especially in the greenhouse, again, is mold mitigation. Right. We're trying to keep it out of the range of different pests growing. If you look at any VPD calculator, especially one that is as easy to use as ours, there's several out there. What I like to tell people to do is just. Just slide that air temp slider back and forth or change the values and just look at how much one or two degrees can actually affect that VPD versus changing your humidity a little bit, and you'll start to understand why doing using only humidity is a lot more difficult to get that exact value. You know, we're kind of stuck with broad ranges at different specific temperatures, whereas with VPD, I can lightning quick just figure out where I. Where do I need to be? You know, where's my mold mitigation risk.
Seth [00:13:49]:
Like, hey, I'm having trouble with humidity. It's 68 degrees in the greenhouse. Do I think moving it up to 71 is going to make a big difference in my product? Depending on the situation, I'd rather go up three degrees and potentially risk losing a little bit of purple versus molding out 20% of my crop. And sometimes that's all the difference is, is a few degrees.
Kaisha [00:14:12]:
Well, that's what I call a breakdown. Thank you guys for that. It was also just a great question. So to our friend out there that has to talk to some folks, just to clarify, relative humidity and BPD, definitely let us know how it goes. We appreciate you. Okay, we're going to keep it moving. This is another question we got in this last couple days. Hi guys.
Kaisha [00:14:35]:
We are new to crop. This is our third run and we seem to get to about week four of flower. And when we stack our poor water ec, we start to get burn on the plants. Even at three ec. I read somewhere that you have to be careful what nutrients brand new use to see if they can be run at higher ecs. We have tried green planet and growth technology and the same thing happens. You guys reference ecs up to ten. We can't get anywhere near that without burning occurring.
Kaisha [00:15:06]:
A lot of people use Athena and reference the high ecs. Is that our issue? Sealed room, CO2 injected one gallon cocoa pots. What do you guys think?
Jason [00:15:17]:
So you know, I'm not super familiar with either of those nutrients that you've tried there, um, most of the time. And yes you are right. That specific, some nutrients you can run a little bit higher than others. However, um, you know, at three, easy, probably should be okay for most nutrients. A lot of times, uh, in the past, you know, I've mistaken tip burn for a nutrient deficiency, um, or nutrient imbalance. So that might be something that you check out. Make sure that you are looking at the, the runoff ph to make sure that you're staying balanced with the composition of nutrients that are available to the plant. Um, and then also, you know, if you feel like getting a leaf tissue analysis, those are a really easy way to, to diagnose what, what specific nutrients might be, uh, in deficiency.
Seth [00:16:05]:
Yeah, I mean this is something we see all the time usually. And I want to highlight the, the main thing I didn't hear coming in from whoever asked the question was runoff ph. We don't have any answers there to guide any advice we're going to give you. But typically if we're seeing, you know, going into end of week two, beginning of week three, even going into week four, depending on how you've been running it. If you've been restricting runoff in attempts to get salt to stack up in your pore water, um, a few things can happen. Number one, if we're not replacing enough of those ions, that ph is going to drift down, which over time, once it drifts low enough, that's typically that classic nutrient lockout. The other part of that is if we're not replenished ph is kind of our indicator whether or not we're correctly replenishing that nutrient balance in the root zone. So if my ph is drifting down, the other thing that's happening is, uh, I'm not necessarily replenishing the ions that the plant is pulling out of that solution at a fast enough rate.
Seth [00:17:01]:
So fast forward two weeks of not running enough runoff, I might be running into the potential issue where my plant is a low, in a low ph condition, so its already struggling to uptake any nutrients at all. Um, and then I was also the balance of nutrients in that solution might be really, really far off of what is actually ideal for the plant at that point in time in its growth cycle. So when youre running higher EC solutions, you know, number one, always watch your ph as far as brands are concerned. Jason and I, we worked with people that have used probably just about everything under the sun. And generally, if you've got a problem with a nutrient deficiency related to that actual brand of nutrient, usually has to do with water quality or mixing technique, you know, I'll give an example. With the water I use at home, certain parts of the year, it's a lot better. It comes out a little lower ph. Right now, it's drier season.
Seth [00:17:55]:
My water's come out a little higher ph. If I don't ph my water down before I mix any salts into it, I see a pretty big fallout of like nitrogen, for instance. And if I run that same mix with all the nitrogen just falling to the bottom of my tank, my plants look pretty yellow and sad after about a week. So I think one really important thing to remember is that we're running drain to waste hydroponics. There's always going to be some waste. Runoff is your friend, it's not necessarily inefficiency. And of all the salts you put into that solution, the plant is nothing ever going to take up. Nearly all of them.
Seth [00:18:28]:
There is no 100% efficiency with the drain away system or with a hydro, a top feed hydroponic system. In general, even deep water culture we're still pulling, you know, if you talk to deep water culture guys, you can ask them, do you replace all of your nutrient solution every week? Do you do half of your solution every week? Do you know amend every few days? What are you doing to keep that, that balance correct? Because like I said, the plants just aren't going to pull out everything. So we've got to always remember that we want to maintain a certain ratio. And to do that, we need runoff. Plus, you can check your ph if you're getting runoff, too. I would bet money on it. It's more of a ph issue over time. It's something we see all the time.
Kaisha [00:19:11]:
That's great advice. Thank you guys for that. Good luck to our friend who dropped that question. All right, we got this question from FCC Mike a few weeks ago. So our first chance getting to it, but he wrote, why would my desiciemens per meter grow, go up as my water content is going up during my p one? Using your meters. Thoughts?
Jason [00:19:33]:
So there can be kind of two main reasons that we see this sometimes, and one could be super obvious if your feed EC is higher than your substrate EC. Well, when we irrigate, it's going to go up. Right. The pretty obvious one, the little bit less obvious one, that can happen even if your substrate DC is higher than your feedc. And that is you're actually pushing some of the salts through the block and they're passing the sensor. Right. So when we're irrigating, it's going to start diluting a little bit of the salts and pushing them down through the block towards the sensor. And so sometimes we'll see that number rise up through NRP ones.
Jason [00:20:14]:
Yeah.
Seth [00:20:14]:
A good way to visualize is, you know, part of the way through your grow. Typically on any salt, salt based grow, the top layer dries out a little bit. You're going to see a little bit of that white salt buildup on top of your cocoa that's happening anywhere. That actually dries out inside the block. So if we have a top part of the block and there is always a gradient, it's always going to be drier at the top than the bottom just because gravity is pulling that down. But as that water passes, it can pick up more salts and as Jason said, move them down towards the probe in the bottom. That's also why a lot of times you'll see a fun curve where if I draw it upside down there, let's say this is our water line. Wonder if red will show up at all.
Seth [00:20:56]:
Let's see, let's say this is our EC line and then don't mess it up. Don't mess it up. Oh, geez, Jason.
Jason [00:21:10]:
Now we got him.
Seth [00:21:10]:
This is it.
Kaisha [00:21:12]:
That whiteboard is like the fourth member of the team.
Seth [00:21:16]:
This is our normal, normal relationship. We like to see between water content and EC. Our water goes down, water content goes down, EC content starts to rise slightly, same as when we are lowest water content point in the day. That's where you see the highest EC in the root zone. Sometimes when that's washing out, what we'll see is instead of this nice line here, the situation Jason brought up, we actually see it go and then normalize kind of a little hump right after irrigation and this is that water going across it and then it's coming back down as it rinses more of that salt down below the probe.
Kaisha [00:21:55]:
Awesome, you guys. Thank you, FCC Mike, thank you for your question. Good luck. Keep us posted. Just a reminder, y'all, we answer questions live as well, so if you have any, be sure to drop them in the chat. We would love to cover them today, but we also have so many great ones that have been submitted that we haven't been able to get to. This one came from mega Stoney bologna. I've been dying to say that they wrote, had a question about trying to avoid late onset of botrytis in flower.
Kaisha [00:22:21]:
Would bringing your p two s to hold water content at say 45 or 50% instead of just below saturation point help or am I off base? I've never missed an episode and I don't think this one has been a topic before, good or bad. Thanks to. We appreciate you mega Stony belloti. What do you guys think?
Jason [00:22:39]:
Yeah, you know, it's not a bad thing. I don't think it's going to make any difference as far as helping, you know, that that plant behaves very similar at 45% water content as it does to 60% water content. And, you know, and the reason that we like to get up to field capacity typically every day is simply because it gives us a little bit larger ability to have a big dry back. Right. So if we get up to field capacity, we can usually run the most efficient size substrate. We can, you know, make big plants in one or two gallon cocoa and, you know, for, for rockwool, you know, if we're only getting to 45%, that doesn't give us a very big window as far as how much dry back we can push. So yeah, you know, maybe you're reducing a little bit of water in the room as far as evaporation, but. But I think in the end, you're not going to see much improvement with that strategy.
Seth [00:23:31]:
Yeah, with botrytis, we're usually looking at environmental factors. Is it a hospitable environment for it to grow? How clean is the environment? Are you doing everything you can to keep it clean? Plant health in general, that's a big reason. For years have been talking about not doing a straight ro flush on your plants. You don't want to cause root death and then have botrytis attack a dying plant. You'll definitely see it if that starts to happen. Some plants respond very well to having silicate added even later into flower in their feed solutions. And then some plants are super duper susceptible, and in some systems, there's nothing you can really do to make that room surgically clean. And every once in a while, you will stumble across a genetic that just isn't actually what we would call commercially viable in regular horticulture and agriculture.
Seth [00:24:24]:
And there's such a wide variety of cannabis out there, and, you know, unlike, let's say, apples, if I go buy a red delicious or Granny Smith or whatever, grow those seeds, they're going to be nothing like the actual fruit I got it out of. With cannabis, if I pull a seed out of a bud, there's a pretty, at least half a chance that it's going to be quite similar in certain characteristics to the parent plants. So we have a lot of variety out there with different subtleties that only come out once we put them into the rigors of bigger production. And I love to remind people that for every apple or pick a fruit or vegetable that you enjoy one of those varieties, they probably threw away a thousand selecting that one, you know, minimum. And, yeah, we're not quite there. I don't want to say we're not there yet. In cannabis, we're still learning a lot about what kind of quirks are out there, what kind of traits are tied to specific lines or linked together. So, as a breeder right now, if I'm just starting and I'm looking at whatever information I can get from different lineages, one big thing that I know I'm not going to be able to get is any kind of mapping of genetic linkage, so I won't be able to know how frequently, hey, when I make this cross, what is the likelihood that I'm going to get a plant that has these three certain traits? And also, has it been mapped enough times to know that two of those three traits always travel together to the next generation, whereas one of those is not linked on the same chromosome and doesn't nearly or doesn't go forward and not as a, it's not a dominance issue, it's more of a variability issue and figuring out how often you can find them.
Seth [00:26:08]:
But, you know, with things like wheat or other more well studied crops, all that information is accessible. If it's not publicly available, I can go pay for it and buy it from the company that has done the work. So, you know, don't forget that sometimes we see plants that don't do what we want. And it's not always because you have a major shortcoming as a grower. I think that's, that's important to remember.
Kaisha [00:26:34]:
Excellent. Thank you, guys. Thank you. Megastoni Baloney. So we had a question here that came from hands down u that was sort of along the same lines. So assuming they write, assuming full saturation is reading 660 percent, what's wrong with only irrigating to maintain, for example, 40%, excuse me, for example, 45% only achieving runoff when needed to control substrate Ec, is that a good technique?
Jason [00:26:59]:
I mean, that's kind of the, you know, the similar question that we answered earlier here where, you know, there's nothing wrong with it. You know, the key I think that this, this question is already, already included is that they're using runoff to dictate ecdemental. Right. And so if you're doing that, you know, if we're only getting up to 45%, then we don't have any runoff and it might be a little bit more challenging to control that EC. So that, I guess that's a good point to add on to our answer from earlier.
Seth [00:27:28]:
Yeah, I mean, when we're, when we're looking at irrigation and managing EC in the root zone, we're obviously looking at water volume, saturation, ec of both our input and what's in the block. And then I, you know, what people really tend to leave out, I've noticed, is PhD. So when we're looking at managing all of those variables at once, what are our levers we can pull? We can adjust feed EC, feed ph and feed quantity. So if I feed it less, I'm probably going to see a ph shift because I'm not utilizing a tool that is run off to manage that ph. And if I'm doing that, I'm also probably building EC. But like we said earlier, that plant's pulling out the better parts of that EC. So even though I'm building EC, if I'm not pushing enough runoff, like, just say, maintaining it at 45%. The EC that's actually in there is not the type of ionic concentration I want for my plants to use.
Seth [00:28:20]:
So if I have ten EC, but most of that is not, not nutrients or not elements that that plant's going to uptake, then it's not really doing anything other than providing osmotic pressure at that point. So, uh, yeah, runoff is ultimately quite important. And to ever achieve a situation wherever you were able to go and hold it at, like, let's say, 45% the entire time and not push runoff except when needed, your other levers now are going to be adjusting your feed, Ec, and pH to manage those two values in the root zone, which is way, way, way more difficult, especially at scale, when you have hundreds or thousands of plants you're trying to attend to. If I'm trying to deal with, you know, six plants in my tenant home, mixing up a different feed solution every few days, I'm changing it. That's not as big of an issue. If I have to go in there and mix up five gallons every few days anyways, if I'm trying to keep 15,000 plants alive, I can't really be mixing that up nearly as quickly, especially if we throw in some varieties in a room where I've got one sensitive plant that is struggling with this. But, hey, the rest of the room is fine. Okay.
Seth [00:29:32]:
Now I've got the logistical issue of how do I manage without using runoff as a tool? How would I manage that EC and PH for that one bench that's doing poorly. But I don't want to change anything on the other ones because the other ones are doing great and they all are operating on the same feed line. So I guess we kind of shotgun approach there. But there are very good reasons that we actually advocate pushing runoff.
Kaisha [00:29:56]:
You guys rock. Thank you so much for that. All right, we got live comments coming in. Thanks for bearing with me, y'all. Learning some new tech here takes a minute, but we did get a question here on Instagram from Trichrome Valley. They wrote, I'm very new to using the terrace twelve sensor. I put the sensor in the pot using the alignment tool. I'm in a 2.5 gallon cocoa pot.
Kaisha [00:30:18]:
The full saturation is showing 47%. And even at 30% volumetric water content, it still looks and feels like a heavy, wet pot. Are these numbers correct? How can I validate if my sensor is working properly? Thank you, as always.
Jason [00:30:34]:
Um, so field capacity at 47%. That sounds just about right for a lot of cocos, um, for the little bit chunkier, chipper cocoa, um, most of the time, we'll see that at about 45% field capacity, um, ways that you can test the sensor. So what I like to do is I'll take a media, um, make sure it's completely dry. So even a, you know, compressed cocoa, two and a half gallon, throw it on a kitchen scale, write that weight down, that's going to be your, your dry weight, and then bring it up to field capacity. That's all right. Okay, fine. So we're going to take our, we're going to take our wet weight, and we're going to subtract our dry weight minus dry weight, and that's going to equal our water weight. Right.
Jason [00:31:29]:
So that's kind of the first step that we're going to do. And so this is going to be all right. How many grams of water are in that block at field capacity, which is also milliliters of water, which is great, because then we can also do a little math, and we'll know the volume of the substrate, right. So we'll take the amount of water divided by the volume of the substrate. And that's going to give you your volumetric water content at field capacity.
Seth [00:32:01]:
You do want to make sure your substrate volume is in liters or milliliters, not gallons. And for that reason, always, usually recommend double checking. So if you can get that volume from the manufacturer, because not all horticultural gallons are 3.785 liters. And different manufacturers actually have, you know, slightly different sizing that they prefer to go with for various reasons. And unfortunately, because of longstanding industry standards, in horticulture in general, they usually try to round those volumes to the nearest, you know, down to a one gallon or up to a two. I've kind of seen it go both ways. So just go ahead and verify that, you know, you're not working with a 3.5 liter media instead of a 3.785 or a big one that I've seen, especially with some of these companies that operate internationally, more like a 4.4 liter gallon every day. You go, man, I'm doing my calculations.
Seth [00:32:59]:
I'm supposed to be putting on 60 ML in this shot and 400 in this other, but I never actually hit runoff. What's going on? Well, if your pot's bigger than what you were calculating on or you thought you were calculating for, then you need, obviously bigger shots. Your percentages are too small. So.
Jason [00:33:18]:
Yeah, and, you know, you can just measure it too, right? Volume of it. So get that cocoa hydrated and make your height times your width times your bio length. And that's going to be the volume of that substrate. Since you are in a two and a half gallon, you also might think about, you know, our template tool. I think we have two gallon at one height and then three gallon might be a different height. I don't remember exactly. I'd have to look at it.
Seth [00:33:42]:
It depends if you had a wider bag or a narrower.
Jason [00:33:45]:
Yeah, yeah.
Seth [00:33:46]:
Two to three gallon tall bag. There's one spot, three gallon wide bag. Yeah, different one.
Jason [00:33:51]:
That's what it is. So put your sensor in there when you're at field capacity. So let's say you just did that activity. So, and then, you know, get some readings off your sensor. See how close it is to your actual. That that scale is going to be. You know, you can't lie, right? When, when we've measured how much water is in there, we know that is the absolute field capacity for that specific media. Hopefully that sensor is, you know, very close to that.
Jason [00:34:21]:
So if it's, you know, if we said maybe we measured 45% actual and the sensor says 47. Oh, that's pretty darn close, right. We can just kind of remember that offset in our head. If it is significantly different, what you can do is start playing with the sensor heights to make it match exactly. Especially if you're in a unique media that doesn't necessarily fall within the expectations of that sensor template installation tool.
Seth [00:34:50]:
Yeah, and I mean, just a few little tips. Like Jason said, hydrate that block. Just going to add onto that and say, don't mess with it. Be really patient, let it fluff up and then measure the actual volume of the block. Because if you start dumping that out into a tote, then try to shove it into a pitcher or whatever else you can measure volume with, there's a good chance you're going to pack it in and it's not going to be a really good representation of the volume right there. And then, you know, as far as that field capacity, it goes 45 47 for a two ish gallon pot. Most manufacturers running a two gallon pot actually do make a more porous cocoa or manufacturer more porous cocoa in that pot size to help growers avoid getting root rot without having to add perlite. You know, traditionally what we do is get your cocoa and mix up a good 30, 30% to 50% perlite in there.
Seth [00:35:37]:
Right. And pack it into a pot. Well, that really sucks to do 1500 times in one morning. So they invented a great product called these compressed bricks that have a lower water holding potential than some of the finer chop cocoa and you can, and it's just for ease of use, like I said. So we don't have to go back in and mix in perlite or something else to help loosen the cocoa.
Kaisha [00:36:02]:
Wow. Okay. Amazing. I don't even know what to say. Thank you guys for that. Excellent. Appreciate that question. All right, I'm gonna keep it moving.
Kaisha [00:36:10]:
We've gotten so many live questions and I love hearing from you guys. All right, girl. Me's our gromy big cypher dropped this on YouTube and he wrote, he wrote, if our base water is coming out high, like 8.0 ph, would you suggest adjusting before mixing as well?
Seth [00:36:28]:
Yes, in my experience, try to get it down closer to a six, five or so before you start mixing any kind of salts in there. Uh, because, I mean, number one, you'll probably get precipitation or just things will not dissolve in solution, certain elements. And then if you go in salt first and then your acid to try to stabilize that ph, we can have some other strange precipitates form that will definitely not dissolve at that point and will always live at the bottom of your tank or in your lines.
Jason [00:36:58]:
Yep, second that.
Kaisha [00:37:02]:
Awesome. Thank you. And big cipher reply. Thanks. Appreciate you as always. All right, going to keep it moving. We got some questions on instagram. I'm bouncing between the two.
Kaisha [00:37:12]:
Humboldt og wrote, can you ask Seth what's going to drive faster photosynthesis 1300 ppfd at 80 degrees fahrenheit temperature or 1100 ppfd at 84 fahrenheit.
Seth [00:37:26]:
So when we're talking about photosynthesis, that's all about the amount of photons coming into the plant in form of energy. So photosynthesis, sugar building, is reliant, not just entirely, but it's like, got a carbon aspect, but it is highly reliant on the amount of light energy coming in and our ability to give the plant enough inputs to actually build sugars in tissue using that light input energy where temperature comes in, especially in terms of, like, why we push first, let's say an 80 to 82 degree leaf surface temp during stretch is plants grow faster and divide faster, so have cellular division happen more quickly at that temperature, we're getting better plant metabolism. But plant metabolism is separate from photosynthesis. So in this case, 1300 ppfd is going to give you more photosynthesis, which is going to allow your plant to build up more sugar. But is that going to do anything for it? Probably more than raising that temp up to 84 and lowering the amount of light. The biggest thing is are you going to be able at 1300 ppfd to manage plant nutrition, which usually at that kind of light level we're seeing, you know, 8910 baseline EC, which is not as easy to manage as like a three to a five, even three to a seven baseline Ec. And then is everything else super reliable in your system? You know, at 1300 ppfd, if we've got a breakdown when it comes to ac or fertigation or specifically CO2, we'll start to see some less than optimal results or we won't see any benefit at all between running eleven versus 1300 if everything else is not supporting the plant to, to be able to handle that 1300 ppfd. And plants also have amazing adaptations to environments that really aren't good for them to grow in.
Seth [00:39:17]:
You know, I've works with some greenhouse growers where we really struggle to get their VPD under a 2.0 the entire flowering time. You know, what does that mean? That means it's tough to get that yield up because these plants are always in a compromised state. However, in like that specific situation, the plants are still healthy, the product still comes out great. They just understand that with the way that facility is built, there's a limitation, they're affecting their yield. So in that case, there isn't a reason to push the really high light. Like, let's save some money on the electricity bill and figure out, okay, where is the cap of what we actually need in our system. So that's kind of the way I would approach it. If 1300 ppfd, you're going to need to have 1550 or even a little more CO2, you know, do you have issues there? Are you able to get that Ec up? And if yes to all of the above, have at it, you know, have fun.
Seth [00:40:12]:
The one thing I will say is with the higher temps, when you're flirting to that 84, usually 85, 86 is a pretty hard line where we start to see bud formation loosening up and pushing into foxtailing and behavior like that on strains that are especially ones that are susceptible to it. Yeah.
Jason [00:40:27]:
And you know, I think I drew some charts. Maybe it was the one of our last episodes not long ago that kind of talks about some of these relationships and also our favorite caveat strain dependent. So certain strains just don't even like to be up, you know, above 1100 ppfd. So do keep that in mind as well.
Seth [00:40:49]:
That's, that's very true, Jason. Strains that don't feed as heavily, for instance, anything that you'd call tending to be a little bit more finicky. And that, that goes right back to that commercial viability. You know, for a lot of these strains, one for quite a long time now, the selection has been for flavor, for nose. Hardly ever has anyone selected a cannabis plant up until probably the last ten years for completely for ease of commercial growth. You know, like, certainly those have existed, but typically, we're always just trying to grow the best bud we could, you know, and, uh, that doesn't always align with commercial production. And because it's plants and we know from other crops that we can actually do a lot with breeding when it comes to things like disease resistance, we are going to hit a time where there isn't a compromise between, hey, this is really good slash, this is terrible to grow. Um, it just takes time, you know, each one of those traits to get into one line could take years.
Seth [00:41:47]:
So be patient.
Kaisha [00:41:51]:
Thank you for that, you guys. Thank you humbleogy for that question. And just, Seth, I want to let you know you're getting a lot of love here on the chat, on the condolences for the passing of your dog. So.
Seth [00:42:01]:
Oh, thank you everyone.
Kaisha [00:42:02]:
So much love right now. Okay, going to keep it moving. We got this question from nick over on YouTube. They wrote, when searing, either generative or vegetative, should the p one period last about the same amount of time? I've heard people state one to 2% dry back veg and 3.6 dryback in general. Would this be the p two drybacks before applying a feed or the drybacks between p one irrigation events? Or is it that we apply a one to 2% shot size in p one veg and a 3.6 shot size in p one general, but with similar 20 to 30 minutes intervals between shots? Or do we wait for a slightly higher dry back in p one shots in gen as opposed to veg p one dryback? Did you guys get all that?
Jason [00:42:51]:
I think so. I like to keep my p one s the same when I'm doing either steering technique, mostly just for simplicity sake. It means that, hey, I can leave my irrigation program for those p one s. And to answer the second question, yes, as well, we're talking about those dry back percentages between irrigations for p two in generally for when we're talking about vegetative.
Seth [00:43:17]:
Yeah, well, and something too. Like a lot of times we're doing this, crops are especially strain dependent. Right back to that. We will push more shots in that p one. Part of what that bulking, you know, the, what's driving the plant. There is just that total number of shots throughout our irrigation window. More shots equals more growth, growth driving cues to the plant. Um, so a lot of times we'll do is, you know, pretty simply my advice to people, if your strain can take it.
Seth [00:43:41]:
Although always, always, always the crop steering. Start out conservatively, you know, don't double your shots anywhere. Start minimum. And you can always add more shots. If you've had too many and you're two thirds of the way through your grow, you can't take them away and make your buds tight again. So always, always be careful there. But uh, yeah, so typically, you know, in vegetative, if we're going for more shots to achieve a certain field capacity, right. That's when we're talking about like that one to 3% shot size generative, more like that three to six.
Seth [00:44:11]:
But always keep in mind, you know, the part of the reason those numbers are suggested is because if you're staying within those ranges, it's really easy to apply those irrigations and not get channeling on pretty much any media you're running. You know, with Coco, sometimes we'll push people to run up to a 1012 or even higher percentage p one shot just to get their p one, you know, this few shots as possible. But really what we're going for in either situation is achieving that field capacity as quickly as possible without channeling. Because in generative, if we can do that in an hour or less cool, that's allowing us to put more and more generative pressure on that plant in veg bulking. If we can get that up to up to field capacity in an hour, well, hey, all my plants are on a closer level. And now I'm going to wait, you know, for anywhere from a two to 5% dryback to start putting on my p two s after the end of p one. But if all my plants have hit field capacity earlier in the day, now my plants are all drying down faster and I'll be able to put those p two s on more quickly. And now I have the opportunity to put more p two s on in the day versus if I had to wait 3 hours to start my p two s because my plant saturation levels are all over the place and I'm still trying to get all of them to hit field capacity.
Kaisha [00:45:26]:
Awesome. Thank you so much, you guys. And Nick, thank you for your question. All right, going to keep it moving over to instagram. This came from igro dabs. They wish I could watch this live, but I have to fix a collapsed blackout shape for the greenhouse. That's important. But question, do you see any benefit in leaving a few lower leaves, but not nodes in a typical schwazi? What do you guys think?
Jason [00:45:52]:
Not really. I mean, most, most of that lower stuff is, you know, especially once our upper canopy is developed, isn't necessarily providing a lot of growth to the plant. Um, now, those are older leaves, uh, which are less efficient, and we're getting less light to them, typically. So, um, I I don't see a reason to, to leave it much for lowers.
Seth [00:46:14]:
Yeah. And, I mean, a good way to think about it, too, is like, how does, how does the plumbing in the plant work? You know, the, the most efficient way that that plant's going to take energy produced in that leaf and get it to where we want growth to happen is the shortest distance possible. If I've got a, uh, and I love these things. Took us a lot of episodes to figure out we needed some drawing tools, but it's amazing. This is going to be a terrible drawing.
Kaisha [00:46:41]:
Thank you for.
Seth [00:46:43]:
Yes, thank you. But if I've got my leaf down here and I got, you know, let's say another one here, but I've gone ahead and, you know, right here. Thank you, Jason. But let's say that I've got no node here. No node here or here. You know, I've really lollipop this sucker up. Like, I'm down to like three. Three nodes per branch.
Seth [00:47:09]:
Well, if I look at plant plumbing, it was a really simplistic way to look at it. We've got vessels inside the plant that bring water and nutrients up, and then we've got vessels that bring water or not water, nutrients, SAP, essentially, down. If water goes up into this leaf, back down the petiole and into the main stem, there's not nearly as much plumbing that's going to take sugar from here to up here. In fact, plants kind of work the opposite way. So if you're going for lower pruning and you've got a leaf, or if you're, if you're going to take that node, that little bud or branch, take the leaf, too. So anytime we're pruning, especially early on or, you know, I heard the term schwazing in there, if you're taking a leaf, take a bud. If it is attached to that bud, you know, the only leaves that you'd ever take that aren't attached to a bud and you wouldn't take a bud is these big old fan leaves that are at kind of the elbows of the tree down here. And, you know, those are, those are the ones that we all know, like, hey, that thing's bigger than my hand.
Seth [00:48:09]:
About four or five weeks in, it's dying back. And a lot of times they fall off on their own anyways. But that being said, those big lower ones falling off and dying and falling off is exactly why you maybe would want to remove those earlier, just as a hygiene measure so we don't have leaves falling onto this table that gets wet every day and then starting to mold.
Kaisha [00:48:33]:
Excellent. Thank you. Okay, I got some really good questions on YouTube that I'm going to. I'm going to see if we can get some overview, more overviews just right before the end of the show. Okay. Rocketbuds wrote in, they want to know what would be some best post drying sops in commercial facilities.
Jason [00:48:55]:
So post drying, one of my favorite things to do is make sure I have reasonable climate control in any areas that the product is going through. So any other processing areas, you know, if you're bucking it, if you're doing any of the trimming, if you're doing some grinding or processing, rolling joints, that type of stuff, make sure that we're at relative humidity in those rooms. That is going to kind of keep our water activity in the product about equal. Right. So, you know, if we're shooting for 0.8 water activity or, excuse me, 0.58 for water activity, then we'll want the rooms about 58% humidity. That means that no water is going to go in the bud. No water is going to go out of the buddha. So that's probably one of the very first things that I would want in one of my sops.
Seth [00:49:42]:
Yeah, I mean, just look at your facility. I think that's usually the hardest thing to manage when we're talking about post production as, you know, cleanliness in those rooms, making sure we don't get any contamination at any point. Accidentally over drying, just in handling, you know, I mean, kind of the old gold standard in the industry is, if you're lucky, turkey bags, but usually black bins with a yellow lid. Understanding that, hey, you know, those lids leak light. Those bins don't seal up very well. So that's one limitation. And then look, working it, you know, I like to use those as an example because I've been into so many large grows now where, you know, I like to think of the dry room, kind of like the veg room in that. In a lot of initial build outs, that's kind of an afterthought.
Seth [00:50:23]:
Everyone makes their money in the flower room, and that's where it all goes. So sometimes we'll end up with a dry room, you know, an initial build out that's either too small, which is a problem, or when we get to, like, the cure in the storage room, it's too big. You know, I don't need to be conditioning a huge amount of air versus the volume of space that my product takes up that I actually need to store. So that's a really big consideration. A lot of times I've seen people take and fill bins, move them into a room where it's actually, you know, they have good equipment in there. The room just happens to be six times bigger than it needs to be to hold the product. And that's just, you know, it's not necessarily even a design flaw in the beginning. It's just like, hey, we had that corner of the building open, and it costs more money to build more walls.
Seth [00:51:06]:
If we want to break this room up, there's an associated cost. We don't want to do that right now. Well, after a little bit of operation, and if you go and look at your water activity and moisture content and realize that, hey, we're throwing out, you know, a couple percent here and there on weight pretty quickly, economically, it makes sense to really build that dry room out and start to invest in handling storage post production. In general.
Kaisha [00:51:34]:
Drawing is extremely important. So, yes. Love that question. Love the answer. Thank you guys for that. All right, another great question here came in on YouTube. This came from Louisiana cannabis. They're asking, would you focus on root training and larger substrates, bottom feeding instead of drips the first week was the comment.
Kaisha [00:51:52]:
But, yeah, root training for larger substrates.
Jason [00:51:56]:
Yeah. If you watch episodes, youll notice that we talk about rotting in as a really, really important part of the growth cycle. And, you know, what were talking about is specific irrigation strategies to get those rich trained, I guess, if you will, from this question here. And so I personally would keep doing top drip. When were doing top drip, were bringing in fresh nutrients, fresh oxygen. You know, if you're doing, you can do a type of, you know, a Feed tray where it's filling up, but for rooting in, that's probably not what you want to do, because we're trying to decrease the water content in that substrate on a daily basis until we hit our target water content. Right. And the reason we're doing that is to keep the roots from stagnating.
Jason [00:52:44]:
So what we'll do is our old, old media. So let's say we're using a four x four on a slab, for example. Well, we want to leave our drippers, obviously, in that four x four. We want to do, you know, very small amount of irrigation through the days that we're rooting in, we do want to do some irrigation because we want to make sure that before those roots have tapped the larger substrate, that we're providing some irrigation to them. Fresh nutrients, fresh oxygen. But what we're doing is kind of trying to dry everything out so that those roots are seeking into to the new media and basically trying to engulf that entire media.
Seth [00:53:23]:
So this is not, not a lot better than a kindergarten cran drunk. But a way I like to think about trading roots, especially in a big media, is if I transplant this plant, you know, let's say it's in a four inch square pot and I'm going into a three or five gallon cocoa perlite mix or living soil mix, whatever you want to call it. The fact is, if you're putting this growing media into a potential, it's going to have a certain amount of aeration. Otherwise, you're going to kill about any plant you plant into it. So if I've got an appropriate amount of aeration, aka if this is a mix that someone has been successful growing plants in, one thing I do know is that I've got a certain amount of wicking potential if I'm going to bottom feed it, right? So if I introduce my water down here, let's say I can even flood it up to a certain point in the media, I'm relying on surface tension inside that pot to wick this water up, right. Well, that is a lot slower and less efficient than relying on gravity to push the water down. And the other part of that is when I transplant this plant, when these are my roots here, I want to push this water past those roots and have that water flow downward. And what that's going to do is pull in oxygen behind it.
Seth [00:54:31]:
So similar to, you know, throwing an air stone into a hydroponic deep water culture setup. But those roots are also going to follow that water pathway because the roots can grow into dry media, right? So basically, by top watering, we're stimulating that root growth downward and also just being more efficient about how you get the water from its source all the way up. Now, if this is being more effective, there is a chance that you might need, especially in the pot size, you're using a much more porous media to actually get enough oxygen penetration in there to not have issues with roots going anaerobic or anaerobic zones in your media. You know, sometimes we can take a go with the three to five gallon pot again, just because that still works great for a five foot tall cannabis plant. But sometimes, you know, I can grow a five foot tall plant in a three gallon or a five gallon pot, and I go to empty it out, and I don't have a, a cohesive, solid root ball. In fact, a lot of those roots have just barely made it to the bottom of the pot. And when the pot's this deep, one thing to consider is, you know, how much money and time are we spending growing this plant? Because if I've got a veg plant for six weeks to get the roots to the bottom of that three foot or that three gallon pot, I've just spent a lot of money pushing roots down. And ultimately, you know, we need a certain amount of fruits to, or roots to get the fruits that we want.
Seth [00:55:49]:
But the plants aren't always going to self regulate in the most efficient way. That's why, uh, that's why we have jobs. You know, it was that easy. We'd just throw everything in the yard and it would grow fine and everything would be perfect. But I, that's where we want to go and manage and say, hey, you know, what's, what's ideal versus what is possible. And with the big media, typically you just have to run a much lighter, you know, more porous media. Like the question earlier about the two gallon pop being 47%, that's pretty bang on, because it's hard to water effectively and keep your pot aerobic if you don't have enough pore space in there. And that pot can only hold so much water because we also need to get enough of a dry back to pull air into that pour space so we can put more water on.
Seth [00:56:34]:
If the pot's too wet all the time, the plant can't drink it either. So that would be my advice. Top watering. That's why we talk about the really small shots. And then if you are in a bigger media, even hitting that point where some old school tricks line the bottom inch with perlite, things like that, that can really help you get better drainage and performance out of the bigger media. And also see, you know, some of the results you're looking for in terms of root health. You know, at the end of a run, we do. We want to, especially if you're in cocoa or a peat mix or something.
Seth [00:57:09]:
I don't feel successful if I can't flip that pot over, dump it out, and just see a mat of roots all the way around, you know, like, I should have to tear it apart to even get chunks of cocoa to fall off of that thing. And if my roots didn't fully colonize that substrate, well, then I just wasted some money, I guess, on substrate.
Jason [00:57:28]:
And ideally, our roots are nice and pearly white. Super bright white is going to indicate that there's plenty of oxygen for super healthy roots. So anytime they start to have some brownish coloration to them, that usually can be an indicator that we're not getting enough oxygen in there and we're starting to be anaerobic.
Seth [00:57:49]:
Yeah. Another important thing to remember, too, especially if you're running a drained away salt system. You're not in a bigger pot trying to go organic or with some type of living soil mixed when we're feeding straight salts. We're not looking for small, feathery roots. You know, the term I love hearing is ropes. But, you know, if you have a hard pot that's full of cocoa and you're dumping salts on that throughout your growth run, they should be some thick, hearty roots circled in the bottom of there. If you pull that pot out and it's not a mesh bag and you see roots that look like they could have been air pruned, probably not quite as healthy as we were hoping, you know.
Kaisha [00:58:25]:
Thank you guys for that. I want to clarify one thing. Seth, did you just say, did you say we need roots to get the fruits?
Seth [00:58:32]:
You do. It all starts with the roots, but the roots aren't the only important part. Right?
Kaisha [00:58:37]:
Yeah, I just love it. I mean, maybe it's a future hat. We're not sure, but actually, I don't.
Seth [00:58:43]:
Think that one's original.
Kaisha [00:58:46]:
Okay. We can't maybe take the credit for that. But also, we want to let you all know we just dropped in the chat over on YouTube our latest article. I'm rooting in brush best practices. So bringing it full circle. I love it. All right, we got like 1 minute left, but this was such a great question. I want to see if we can get it in before we go.
Kaisha [00:59:03]:
Michael dropped us on YouTube. Can you give an overview of tip burn and leaf twisting starting after stretch? Starting veg steer is basically too much dry back. Do I need to stay under a 30% dry back from 100% field capacity?
Jason [00:59:20]:
So, you know, usually 100% field capacity is going to be, you know, like 70% water content if we're in Rockwool and either 45 or 60 if we're in cocoa. So, you know, I think those measurements are a lot easier to discuss on because whenever we're using percentages. It's nice to just have one static number that we're taking the percentage of, and that's going to be the volume of the block. Right. In which case, you know, if we are at a 30% dry back, that's usually going to be during our generative type of cycling. You know, there's a chance if you're seeing that in vegetative, that we might just need to upsize the substrate. Right. And use a little bit more use a little bit more substrate.
Jason [01:00:02]:
So we've got a higher amount of water available to the plant. So that that's kind of what I would think is let's, you know, stay consistent with our percentages so we can, you know, getting that. Good idea. Are we going from, say, 70% in Rockwool? If we're at 30% dry back, we're hitting 40% water content, which is kind of right on that edge of when we're starting to possibly jeopardize the qualities, the characteristics of that rockwool.
Seth [01:00:33]:
Yeah, and I think it's the really important thing there is to look at the symptoms on the plant and start working backwards from it. We've got leaves that have some tip burn. There's a little bit of twisting. I don't see a picture in front of me, so I can't, like, judge how dark green it is. Or if we have any leaf curling, anything that could be close to, you know, latent virule expression, that's always another one that'll sneak up. And why are my leaves so weird looking? Oh, it wasn't me, it was the virus. But anytime you've got, you know, basically distal symptoms in the plant, so when those leaf tips are burning and we're starting to see growth, especially like on the leaves, are the farthest, the highest upenness, especially if that's where that's the main symptom expressions. Basically, that means the plants having the most trouble getting water and nutrients to those cells that are the farthest away in the plant.
Seth [01:01:21]:
Now, is that happening because we have an environmental situation where the room is too dry, therefore stomata are closing up, and those are actually just starting to dry out and burn because we're not getting enough water up there. Do we have too much salt in the media to the point where the osmotic pressure is not allowing the plant to effectively give water and nutrients to the very tips of the leaves? That could be part of it. And in that case, that's why we want to see that time series root data, root zone data to go, hey, this EC has never gone above a 6.0. I highly doubt that that's the reason that we have this going on. Then the next we'll go down is looking at PH. Do we have a situation where the ph is slightly low? Are the leaves just burnt on the tip? Are we seeing other nutrient deficiencies, symptoms? So there's kind of a long road to go down to figuring this out. But the first place I would start, especially, you know, we're talking about a little bit of, you know, I guess, confusion on the definition of at least the way we communicate about drybacks. Watching to make sure that at that critical time when you're switching over from generative to vegetative, you haven't hit a point where you've already been over drying your plants accidentally for a few days.
Seth [01:02:30]:
So, you know, by the time you, usually by the time we see symptoms on a plant, that's past when the corrective measure needed to be taken to avoid those symptoms. So first identify. Does it have to do with the switch from generative to vegetative? Or am I just seeing a symptom that's been building up for the past three weeks and now I'm reacting to it when realistically I need to be potentially pushing more runoff a week earlier to correct the ph issue. Or maybe you're feeding too high and not pushing any runoff. So now we have an absurd amount of salt stacked up in there that's way beyond anything the plant should be able to take. You know, there's, there's quite a few factors. If you're not absolutely killing your plants, I would really start focusing on the drybacks. And then, you know, remembering that there's a lot of talk around dryback percentages.
Seth [01:03:18]:
And like any kind of number or scale, once we put a number on something, everyone wants to say, mine's bigger. So when we're talking about drybacks, it's not about that percentage being bigger. That's, that's great. If you want to go brag to your friends that you run a 60% dryback, cool. But really what it's about is that time from last irrigation to first irrigation the next day. And if you're planning your irrigation around a specific dryback percentage, really focus on going, okay, what is the minimum that I need, which is generally ten to 15% volumetric water content, you know, leaving the media so that we get good aeration and we can put on enough water to treat the plant right the next day. If I can push 30% 40% down from like let's say 70 or 65. Great.
Seth [01:04:07]:
But is that necessary? No. And as we've talked a bunch, the plant, as far as how it's dealing with the environment that its roots are living in, it's not changing anything between 65% and 45 and even 25 in most media. So really, really getting away from that, wanting to have a specific number on the dryback and moving over into looking at time because also that number is so far from apples to apples. When we talk about what we're comparing, I mean Jason and I, between us probably have four or five different brands of cocoa at our houses. Us talking about what the dryback percentage on those is not going to relate to one another because they're all slightly different sized and we have different sized plants sometimes. So thats not really going to get us very far if im trying to copy something hes doing or vice versa. Weve got to look at what happened and what can I actually achieve? One of the things I can achieve is those timed irrigations and stretching that time out.
Jason [01:05:07]:
Yeah, I think why people get so caught up and excited about dryback percentages, you know, the better number would be to think about dryback as far as how much water volume was transpired. And so for me, rather than even looking at some of the percentages, and it just kind of gives you a target so you can start structuring your irrigations. Right. But obviously, well, we always want our amount of transpiration, water loss due to transpiration as high as possible because that means that we're photosynthesizing as quickly as possible. Comes back down to like that VPD that we were talking about. But what I like to do is look at how much change in our water content loss happens when our lights go off. And so what's happening here? So this first section is going to be lights on. This section's lights off, right.
Jason [01:06:09]:
When we're lights on, we've got a little bit of evaporation, but a lot of transpiration is happening. Right. And so that's what, those are the two factors that are contributing to our water loss here. And when we turn the lights off, we don't have very much transpiration happening. So this is just evaporation. So the change in the slope here would be indicating, you know, the more that that slope is, the more transpiration that we have happening. If you have a line that is fairly straight ahead, that's not good because that means that you don't have a significant amount of transpiration happening. Right.
Jason [01:06:48]:
If there's no change in that water loss. That means that our transpiration wasn't contributing a lot to that water loss.
Seth [01:06:54]:
And that's not, that's, that's given him a lot of slope in that situation, I'd say, well, yeah, usually we see is a little more like, you know, barely, barely going down over a long period of time.
Jason [01:07:07]:
I guess that's what I get for hassle in your drawing earlier.
Seth [01:07:09]:
Yeah, I love it. But, yeah, that's the thing. If you're not, if you're not achieving those goals, get, get, try to get away from that and look at what are the other factors that are driving it. You know why I really like Jason's approach with the volume? Because that's also a good way to explain to people why if you had success with a 25% dry back in your one gallon and you're freaking out about only getting ten and I, you're two, you might actually be fine. You know, if you're at 42% and you're two gallon, you're drying back to 32%. That's great. That's perfectly healthy. And it's going to still be about the same volume of water as that bigger dry back in the smaller pot.
Seth [01:07:44]:
So, you know, as, as much as we want to put numbers on everything, sometimes just relax. And also, if you do have the graphing data, that is one way to, to actually kind of go back to a little more of a, I want to say hands on and not by the numbers. You can go a little more visual and intuitive just by looking at a graph shape and not necessarily trying to put numbers on anything, just understanding what you need to see in the garden every day and what the graph should reflect in terms of like, you know, it's painting a picture with what you're doing in the garden. If it looks good, you're good.
Kaisha [01:08:18]:
So good. All right. We went a little over today, but we missed you, gromies. It's hard on us when we're not on the air, so, but before we go, I want to drop a couple of quick announcements. So next Thursday, July 25, catch members of team Arroy at the Connect's next event, which is Lightworth, Sacramento. We will drop the RSVP link in the chat. A couple of our guys, John and Sienna will be there. Come over, say hi.
Kaisha [01:08:43]:
And then the MJ Awards is accepting nominations until August 18. If you love AROYA Office Hours, please consider nominating us for content creator of the year. We will drop that link to the nomination form. And as always, we appreciate your support and for coming on the show and dropping these amazing questions. So good. All right. With that, Seth, Jason, producer, Chris. Thank you guys so much for another great session.
Kaisha [01:09:07]:
Thank you all for joining us for this week's AROYA Office Hours. To learn more about AROYA, book a demo at AROYA IO and our team will show you the ins and outs of the ultimate cannabis cultivation platform. If you have any crops during our cultivation questions you want us to cover, drop them anytime in the AROYA app. Email us at salesroya IO. Send us a DM. We're on Instagram, Facebook, and LinkedIn. We definitely want to hear from you. And if you're a fan of the pod again, please do leave us a review on Spotify, Apple Music, YouTube, the MJ Awards, wherever you listen to your podcast and we appreciate the feedback.
Kaisha [01:09:38]:
Be sure to subscribe to our YouTube channel so you never miss an episode. Thanks, y'all, and see you at episode 109. Bye.