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Seth Baumgartner and Jason Van Leuven open the mics for your crop steering and cultivation questions.
Kaisha [00:00:00]:
You. What is up, Growmies? Welcome to AROYA Office hours, your source for free cannabis cultivation education. I'm your moderator, Kaisha, and this is episode 92. If you're on the hangout or checking us out live on YouTube or Instagram, drop your question in the chat. And if it gets picked, we'll cover it during the show. Great to be back in studio with you guys. How you doing, Seth and Jason?
Jason [00:00:21]:
Good.
Seth [00:00:21]:
Doing good.
Kaisha [00:00:22]:
Sweet. Sounds like you're ready to go. And this great because I have a really good one to get us started. We're going to have a screen share in a second. Let me read the question. Someone is looking for advice. They want to know what is this? They're on day 22. One gallon Coco core, 3.0 feed EC 5.7 feed pH 6.2 run up pH substrate.
Kaisha [00:00:43]:
EC is six to twelve. The buds never produced white pistols. Bottom buds, the same as the top. Half. The room right now looks to be spreading. Cut one down and looked at the roots. Brown, but not slimy. All right, so let me show you the photo here.
Kaisha [00:01:01]:
Mixing it up, y'all. All right, this is what they're dealing with.
Seth [00:01:12]:
Oh, Chris is pinning it bigger. There we go. We can see it a little bit now.
Jason [00:01:21]:
I mean, if red zone is brown, one of the first things that I would do is check dissolved oxygen levels. So easiest thing to do is take your reservoir temperature. Get an idea of is it high or low? If it is too high, then definitely could be causing some strange issues like that. As far as how the plant is reacting. Anytime that we have low levels of oxygen in the root zone, it's not going to be as healthy. Other things that we can look at there that might be related in the same area would be how wet are we running that? Are we doing appropriate drybacks? How often are we irrigating those type of issues? I mean, if it's spreading across the room, then it just may or may not be that some plants are being affected by that condition, that are obviously some type of infection going on with those plants.
Seth [00:02:14]:
Yeah, I mean, I think the first thing, number one, the brown roots are like a huge telling tale, right? We can tell root health is not good if we have brown roots, even if they're not super slimy. That might have more to do with how dry was it when you did go check those roots. If it was super wet, those roots might have been a little slimy or as time's going on, might see more and more rot. As far as Jason is saying, a total dissolved oxygen content, one of the biggest things we've seen over the years, people having, let's say a fertigation room or basically a reservoir, either in the room or right outside the room, in the hallway, sitting at an ambient temperature that's much higher than our desired, like 65 to 67 degrees for our input water. So if that water is living above 70 degrees, we're seeing low total dissolved oxygen. And then also with that low total dissolved oxygen, and better, a little bit higher temps, we're looking at just basically a great breeding ground for different bacteria. So if your water has been warm, if it sits stagnant for a while, and you've hit a point where you have an infection in your system, now, it can spread throughout your basically entire grow. It might start out contained to a table, but your plants all live on the same table.
Seth [00:03:23]:
They're all watered by the same fertigation system. So if you have any kind of contamination, you're going to see it start and typically slowly spread. To me, that plant obviously looks a little sick, but if we're seeing the brown roots, that's probably the big thing. And one thing I would do if you are pulling down any of those plants as they die, is just do a cross section of the stem right at the base of the plant. Get out your handy dandy magnifying glass, real high tech, but do a cross section of that stem right at the base and start to look for things like, basically brown build up that you can see with your eyes inside of the floam, and then look at the base of that plant. Even dig down an inch or two and start looking for lesions on the plant and on the buried part of the stem, basically the crown of the plant. And if you're seeing any lesions, one of my big tricks is just go take a toothpick. If you see a brown spot, poke it a little bit.
Seth [00:04:16]:
If it's squishy, you've probably got a form of root rot, whether it's fuserium pythium or a handful of others. And at that point, evaluate if it's early enough in the run that it's really going to take everything out, might scrap it and clean everything. Probably a good idea. If you're noticing that in the first few weeks and it's overtaken enough of your room that you're saying, well, if your choice is, I'm losing money on this run, how much am I going to lose, and how is this going to affect my quality? If I've got plants that have a serious root zone infection, I might get some through to the harvest stage. But I'm definitely taking, obviously, a huge hit on yield because I'm going to kill a lot of plants along the way, and then typically quality is also going to suffer and I'm going to be battling things like aspergillus in the dry room and just a lot of stress towards the end of flower. So those are the first things I'd check. It sounds like your EC and everything else is in range. We're not seeing massively burnt leaf tips that would indicate huge ph fluctuations or giant EC swings.
Seth [00:05:19]:
Your EC is right in line with where we expect to see it with any. If you're hitting 900 to 1000 plus ppfd, we do want to see that little bit higher ec. That six range and twelve on the dryback is fine. One of my questions, I guess, would be, if I could ask this person is, have you ever had a water quality test done? Because a lot of times when we see a situation like this, we're looking at number one trend. Obviously, we've got some sort of root rod issue. If you have access to labs, it's fun to identify what that contamination is. Is it pythium? Is it fusarium? Is it something that's coming in from just right outside your front door? Is it being tracked into the facility or working backwards from the table? Do we have an infection point along the way where that contaminant is being injected into the room? And that's why we're seeing it slowly overtake more and more of the room. And don't discount if you've got an ro filter, any kind of water filtration system.
Seth [00:06:18]:
If your actual filter becomes contaminated, you could have a contamination point right at what you think is the cleanest source of your incoming water.
Kaisha [00:06:28]:
Wow, you guys, thank you. Great advice. Good luck to our friend out there. Thank you for the photos. Kind of fun to be able to do a little show and tell today. All right, we're going to keep it moving. We have tons of questions that have been submitted recently. So this one came in from Trichome Valley.
Kaisha [00:06:43]:
Over on Instagram, they write, ideally, how far should my lights be from the plants after stretch, I'm using 1000 watt double ended HPS in a sealed room with supplemental co2 in three gallon coco pots. Hand watering. And is there any way to put the lights closer without causing issues? Thanks a million.
Jason [00:07:05]:
So for HPS, I like to usually be three to 4ft from the top of the canopy. And the reason for that is, obviously, if we've got appropriate airflow. That's going to give space for the heat to diffuse from those lamps and just help homogenize the environment above the canopy. Sure, you could go a little bit closer if you've got really good airflow, or possibly you've got a way to cool those lamps a little bit better. Challenges that you're going on to there is that when we're working with HPS bulbs, we need some amount of space between the light so that we can get some off axis lighting down into the canopy. If we're too close, then it's going to be hard for your light spacing to get consistent lighting across that canopy, and that's going to be a really valuable thing. And ensuring that you've got a consistent crop both horizontally throughout the checkered board of the lighting and vertically so that you get some cross sectional lighting down into the canopy. So three to 4ft is kind of the answer that I would go with.
Jason [00:08:08]:
Ideally. Obviously, this can be very successful to have some, like a light rack that you're raising and lowering until your plants are at the end of stretch. So if you are shooting for three to 4ft throughout the entire plant lifecycle, you can see a little bit faster growth early on. And you can also kind of have a tendency to keep your lights ramped at the appropriate level.
Seth [00:08:32]:
Yeah, what we're trying to do there is just maximize light intensity in the canopy at the level that we want it.
Jason [00:08:36]:
Right.
Seth [00:08:37]:
And as Jason brought up, there's a reason. With thousand watt HPS, we've landed on a four x four or five x five design at various heights because we're trying to get an even spread. So lower the light, you're shrinking that spread. If you're going to start doing that, I highly recommend having a good PPFD meter that you can go in there and start to map out, like, hey, if I drop my lights down to 3ft instead of 04:00 a.m.. I, actually promoting a dim spot in the area between the two lights and then HPS or LED. One incredibly invaluable tool every grower should have is a laser thermometer. Obviously, there's ranges on how nice and how accurate you can get. When I'm trying to set my lights, I really start to look at what's my PPFD at my average canopy height, or am I growing Christmas trees or am I growing bushes? That's going to affect it a little bit.
Seth [00:09:23]:
If we've got a flatter, more planar canopy, we can get that light a little lower and not torch oddballs sticking up, basically. And then the other thing is use that thermometer. If your leaf temps or your surface temps of your plant are cresting over, let's say, 86 degrees, I found to be kind of a magical number. That's when I'm starting to see a leaf surface temp or a plant surface temperature that has, it's too high. I've got too much VPD, too high of VPD in that immediate few millimeters around the plant. Even though the rest of the room looks good, that environment we're targeting there is too hot, too dry. And above 86 is usually where you start to see foxtails, loose bud formation, those classic signs that your HPS lamp is getting too close to your plants. So like everything else, document it, start trying to optimize it.
Seth [00:10:10]:
Different bulbs are going to be a little different. And right back to what Jason said, if we, or let me extrapolate on that. In a perfect world, right, we would have a light lifting system that constantly maintains that 36 inches or so. Do we all have that in our grow rooms? I don't, unless I go in there and adjust my lights manually. So for a lot of us, we are stretching the plant up into that prime zone of like, high PpFD that we want. But there's always that balance because you got so much radiant energy coming off your HPS bulbs.
Jason [00:10:44]:
Yeah. And ideally, if you're doing a good job documenting your PPFD throughout stretch, those plants are kind of going to get closer to the lights. You're going to get a higher PpfD and it's just going to naturally ramp up into the highest intensity that you want. Right. And so if you do a good job kind of preparing and organizing what your growth schedule is going to look like, you can get away with not necessarily having to do much raising in there.
Seth [00:11:10]:
Yeah, in my own personal situation, I can get away with at least the light that I have with the amount of co2 I have. Just take my meter out and set my light intensity to where I want it to be in terms of PPFD compared to where those plants are. So for me, what that means is I actually might be running kind of a higher intensity early on because my plants are a lot further away from the light, but I'm still trying to get six to 700 ppfd right at flip there. Well, as those plants grow up into the zone, that's 1000 plus. I'm actually turning down my light intensity when they're increasing over that. Now, that's because I have co2 limitations in my space. I'm not running like a full bore co2 set up at home. But that being said, that's what a lot of commercial growers typically end up doing.
Seth [00:11:55]:
You're trying to adjust it there and then, hey, if you don't have an automated light moving system, what's the labor payoff in moving all of those and then looking at like, okay, for our first three to four weeks throughout stretch, that light energy is helping that plant build structure, but it's not actually filling out buds yet. So with a lot of strains, we can lower those lights, get more nodes stacked on because we've got more light energy, but sometimes at quite a significant expense, depending on how hard your facility is to go. Adjust that like big greenhouse situation where I got to plot an extension ladder to adjust every single light. Probably not really the solution I'm looking for. If that's thousands and thousands in labor to do it every cycle, or if it's going to be 100 grand for a light lifter set up for that room, I've kind of got to start weighing how much am I gaining out of actually moving those lights? And from what I've seen, sometimes it's not the biggest impact at scale. As long as you've been able to tune everything else to deal with it.
Kaisha [00:12:59]:
Great stuff to consider. Thank you for your feedback on that. Tricon Valley. Good luck and keep us posted. All right, we're going to keep it moving. We got a couple of questions here on YouTube. Dr. Green Thumb Aaron, good doctor wrote, I work in a mixed light greenhouse and we've been getting reveg by the heater.
Kaisha [00:13:17]:
What do you think we can do to stop reveg?
Jason [00:13:23]:
I mean, there could be a ton of variables going on here. One of the first things that I would do is so it sounds like you've made one of the first steps and that's trying to localize it. One of the things I always try to think about too is is it actually the heater that's affecting it? Have you done things like checking your blackout, making sure that we're not getting more light exposure than our 1212 on there typically? I guess another thing that would probably be good is know the differential in temperature across your greenhouse. I mean, that was one of the challenge. First challenges that I faced while operating 4000 square foot greenhouses and that was just a huge temperature gradient. So if you can implement things like hvac socks, it's going to be an improvement for everything. If your plants are revegging because the temperature is so high, then it's definitely going to help. But my first off impression here would be probably check for other causes that might be doing that.
Jason [00:14:20]:
Typically unless you're way up in temperature, you're not going to see a gradient because of that or reveg specifically due to that.
Seth [00:14:30]:
Yeah, I've personally used up a lot of gaff tape sealing up corners of greenhouses and stuff where I've got a small light leak that's not significant enough to affect the entire crop. But right next to the front door to the room, let's say. Especially if I've got an indoor set up and I'm running my room at night. So let's say it's light outside, I've got a little light leak only affects those plants. One thing I have personally seen is a few strains that will do some weird things. If you try to drive them vegetatively too hard, we'll see continual stretch. The plant will throw out single leaflets. It's showing some of those reveg symptoms.
Seth [00:15:06]:
But I think it's important to try to quantify what is it. It's close to the heater. But in my experience I'll go back to that magical 86 degree number. Unless my plants start to go over that, I'm not seeing terribly adverse effects in terms of growth morphology. Going beyond that, there are some finicky genetics out there. We've talked about it a fair bit on this show and I think definitely in other platforms where, hey, one thing we've seen is this particular strain. It doesn't like high EC for instance. And it doesn't like successive bulking signals.
Seth [00:15:40]:
It promotes too much stress and growth. We get some strange characteristics. If that's something that that plant is sensitive to, that starts to turn into an evaluation of, okay, am I getting the yield and the quality that I want out of the way? My system works right now and can I change my system enough to accommodate it, that strain? And if I can, is it worth it? Am I going to get a premium on that? So there's a few factors there. Especially it depends on kind of what scale you're at. If you're Jason, what under 2000 price of making facility improvements is a lot more economical than if you're at 2030. 40 50,000.
Jason [00:16:25]:
Just kind of bringing up the last possible cause would just be maybe some nutrient issues going on in there. If you're running a really high nitrogen mix in there, you might try and examine and then make sure that that wouldn't be causing it. That's probably one of the last things there that I would check on the know. As always, when we're making recommendations, cess and I are thinking about, one, some of the experiences that we've been through to identify these issues. Two, a lot of times we're approaching with the most likely solutions that we can come up with. And then three, kind of going out there and extrapolating what science suggests and what a lot of our growers have experienced. When we list these things, there's a chance that it could be a couple of them. Usually we just try and try and start with the one that we think would be most obvious or easiest to cross off the list.
Seth [00:17:18]:
Yeah, and if you've crossed all those off, just like with most of the issues we talk about and that happen in the flower room, look backwards in your process. I just remembered there's another situation I've run into that was not my fault, but did directly infect me. Go make sure your moms don't have any bracks or pistols on them. If your moms are starting to preflower and you clone a pre flowering plant, put it back into veg. That plant doesn't immediately reveg. It can have a lot bigger effects on the morphology of your plant throughout the flower cycle than it would seem to be. And it's kind of inconsistent. Sometimes you can take a pre flowered clone and get decent results.
Seth [00:17:55]:
Other times you'll get a few weeks in and go, why is this thing just acting so, so weird? In that case though, that generally affected that whole row of that strain because all of those clones were pulled off of the same pre flowering mom. So that's another thing to look at is like localized versus across the population. Right. And how bad are things being affected? Like Jason, you brought up high nitrogen. Do you have an inline system where you've know, five gallons of veg mix that you pump to the veg room first? Now you're feeding the flower room, but that first bench is getting hit by a lot of nitrogen, whereas the successive waterings aren't. There's a lot of little scenarios and basically knocking them out one by one and not going with the shotgun approach is the best way to finally identify it.
Kaisha [00:18:44]:
I think that's quite a prescription for Dr. Green. So I'm Aaron to look into. Thank you guys for that. And you were talking a little bit around about nutrients, so we actually is perfect segue into my next question from YouTube. From Jacob. We have a question about feeding. What's more important, reaching field capacity or trying to reach target drybacks.
Jason [00:19:04]:
For me, it's hitting field capacity, and the reason that I'm doing that is because field capacity is something where we're stabilizing our substrate and reaching target drybacks. Yes, it's great because then we can follow some of the crop steering recommendations that we have in there, but there's a lot more things that we possibly don't have as direct control of. So we're thinking about, all right, if we're already in a substrate that's too small or too large, then it's going to be a challenge to hit the drybacks that we need. Maybe we have a strain that just doesn't drink as much water as we're used to. Again, going to cause some challenges to hit the drybacks that we need. If we don't have appropriate light levels, it might make it harder to hit the drybacks that we need. If we're in an unsupplemented greenhouse, then we're always going to have to adjust our irrigations based on how much lighting that we can get in that day. Some days you're going to see much larger drybacks.
Jason [00:20:00]:
If we have a day where it a little cloudy and it's 30 micromoles, obviously we're going to have substantial difference in how much water is used versus hitting 45 to 50, ideally for something like cannabis.
Seth [00:20:13]:
Yeah. At least for me on that comparison, like Jason said, basically when we change volume, media size, that dryback number is going to change based on the plant size and the media size that we have that percentage goal. I usually draw a hard line and say if I'm getting less than 10%, my media is probably too big for my plant or I've got some other problem that's preventing transpiration, usually environmental, or having to do with plant health. As far as strategy goes, though, in crop steering, we're looking for those drybacks, we're looking for irrigation timing, but we really can't forget about pH and EC management. And what that requires is crop uniformity, right? So if I don't take all my population that's on a single valve and try to get it back up to field capacity that day, that means I've got a bunch of this population that's now living under slightly different conditions, and then that can tolerate more or less dryback. And when that's happening, if I'm not pushing that runoff every day or every few days, I'm losing my ability to manage pH and Ec as well. So it's kind of a fine balance. However, that's part of why when we're looking at media choices.
Seth [00:21:21]:
For example, we kind of tend to see the best performance in between 45 and 65% because that's giving us enough pore space to be scientifically great for the plants. They've got plenty of access to oxygen. And if we used something that, for instance, we could grind that coco to almost a powder, make it straight up coffee grounds, and get that water content way up, but then it's not really the best media for growing. Right? So field capacity, number one, and then drybacks are great, but really getting that proper media size and then something with good enough porosity and also good enough water holding capability to hit those dryback and crop steering goals. If I'm in too small of a container, going to overdry the plant, most likely I'll be in kind of a risky situation where if I miss a watering, I might have plants drop. If I've got too big of a pot, I'm never going to be able to bulk it. But it's a holistic approach, I guess. And I think we've kind of talked to ad nauseam about this.
Seth [00:22:24]:
Your dryback numbers are very important, but if you're getting above 10%, we've got something to work with, especially if you've got a low flow dripper system where we can really precisely put small amounts of water on those plants.
Kaisha [00:22:40]:
All right, Jacob, thank you so much for that question. We actually just got another question related to drybacks here on the hangout. Hugo. I'm going to read it, and if you want to unmute and add to it, feel free. But they want to know, do you think that it is possible to crop steer in 20 gallon coco pots by extending drybacks to multiple days?
Jason [00:22:59]:
Yeah, absolutely. As we always say, everybody's crop steering, regardless of whether you're doing it on purpose. Right. The plant is responding to the environmental and irrigation cues that it is in. Right. And so that's what we talk about when we're saying steering plants, responding to it, and they're going more generative, more vegetative. The last question, more revegetative, because of some cue that it was given and something like a 20 gallon, hopefully we're growing pretty big plants to make sure we're taking advantage of having a 20 gallon. A lot of times we see that back in the days before drip irrigation was really popular, and that's just simply because you didn't have the time, the labor force, in order to irrigate as often as we recommend these days.
Jason [00:23:47]:
So, yeah, in something like a 20 gallon, what I would do is try and get an estimate of how much water content loss that I have and then start to judge it off of that. If we had a really large plant that was doing, let's say it was a gallon and a half to two gallons a day, I mean, that's going to be a monster as far as water content usage goes. So that would be, what, two gallons in a 20 gallon container that you're going to be at 10% water content loss a day. So, yeah, every three or four days, you might be getting a shot to be generative.
Seth [00:24:26]:
Yeah, I think you nailed it there. Everyone is crop steering with that 20 gallon set up. Unless you're growing like a 14 foot tall, six pound outdoor monster plant, your plant is going to probably lean towards being super generative, high quality, easy to maintain. I'd love to know if you're growing indoors or outdoors with the 20 gallon, because that's going to affect a lot. Not so much what you want to be looking at, but sometimes the ways you go about gathering that information. If I've got a 20 gallon pot outside on the ground, there's no air gap under that pot. I've got a little bit different moisture conducting or way that moisture conducts through that down into the ground below it. And also, potentially, if I'm outside, some access to that moisture that's in the ground underneath, that's going to affect how often I need to be watering.
Seth [00:25:13]:
If for anyone that's in huge pots, especially if you're not used to let me in 20 gallon pot, we can't go pick that up, right? Or I can't. I'm not big enough. Even starting with a basic soil moisture potentiometer or something to just help you start to put numbers on where that's at, and then understanding, okay, what value do I need to see that's an action item?
Jason [00:25:35]:
Yeah, I think another thing, eight foot.
Kaisha [00:25:40]:
Plants and indoor growing.
Jason [00:25:42]:
Cool. Yeah, I'd probably still be going a little bit smaller substrate than that just to be more manageable as far as after I harvest and types of irrigations that I can get away with. What I was going to say was, though, it's really important to conceptualize, when we are in larger substrates, we're going to encounter a greater gradient of water content than we will in smaller substrates. When we're talking about things like working in slabs, one two gallon coco, or Hugo's or even jumbos, the substrate is small enough and made of materials that are designed to be very consistent. And so a lot of times when we're talking about water contents. We're kind of just being like, hey, we're at 40%, we're at 50%, we're at 60%. And that's just trying to say, hey, here's an average for that volume of substrate. Obviously, when we're getting into something like a 20 gallon, a lot of times you're going to see at the top, and especially if you're in a fabric bag or some type of porous pot like that, you're going to be getting pretty close to zero water content on the outsides of that.
Jason [00:26:50]:
And you could still be at, say, 50% water content towards the middle of the pot. And so it's important to conceptualize that and think about, all right, where does in this pot my bulk zone exist? And then try and think about that in respect to the numbers that you're trying to achieve. One of the nice things about that gradient and when you are in a large substrate like that is the plant's going to balance out some of that water content usage because the root zone has that gradient. Right. That's going to be a little bit more forgiving because even if we are pushing it lower, there's still going to be some available water down into the middle of that substrate.
Seth [00:27:31]:
Yeah, and if you're in a 20 gallon pot as well, I would say there's a good chance you're not going with the straight salts route. Usually at that kind of media volume, you've got different amendments people are working with. If you've got an actual mix that you've buffered and has decent nutritional content, you're not relying only on your salts. It's going to be a lot easier to basically maintain ph over those multiple day drybacks that you're likely to have to do early on in the flowering phase. Also, I guess we'll talk, too. Part of the reason commercial agriculture, commercial horticulture has gone away from big pots like that is also to get the veg time down. So eight foot plant in a 20 gallon pot, you're vegging for more than two weeks is my best guess. That's a little bit different production cycle than typically we see in most bigger grows.
Seth [00:28:20]:
Again, not to say that it's bad by any means, you just don't have quite as precise a control with your individual plant size, unless it's just a monster. And yeah, it'd be very interesting to see what else you're working with there, because there's a lot of factors that could really help you decide what you're going to do besides just going super generative and waiting a long time for these drybacks.
Kaisha [00:28:44]:
So then, just to close out this convo, Hugo dropped. So is proper vegetative steering possible in bulk weeks?
Seth [00:28:53]:
Probably not with an eight foot plant in a 20 gallon pot. Yeah, you can do some.
Jason [00:29:00]:
I'd still encourage some amount of repetitive irrigation and they can just be very small. The thing that is nice about that and the reason that we're always pushing people towards a manageable sized substrate is just because we're bringing fresh nutrients, fresh oxygen in there, and we're providing those bulking cues. That being said, obviously we don't want to keep that substrate too wet. So I would always, never try and do vegetative irrigations more than the transpiration rate or evaporation plus transpiration rate of that plant.
Seth [00:29:36]:
If I was veggie, yeah, you can do it, but you're not going to want to push it too hard. You're not going to make the classic jigsaw graph that we talk about. You're going to have a lot deeper valleys, fewer p one or p two s rather. It is doable. It's going for the generally we look at as like the lower effort approach to trying that there's one end with a bigger pot. The other end is something like a six x six x six rockwool cube where we don't have the freedom to not water in the last two weeks throughout the day, because we're just completely out of water holding capacity in that pot compared to plant size. So that's something to think about over time. If you are used to growing in the 20 gallon pots have been for years.
Seth [00:30:21]:
There's many people out there like that. I always encourage you to try a little bit smaller pot and start playing around a little bit and see what works best for you. Because when I think of growing indoors with a 20 gallon pot, the first thing I think of is my back. How am I moving that media in and out? Is the difficulty of handling that media in the facility going to make it so I'm a little less lazy about moving them out. Like if we go back to years and years ago using 20 gallon pots for moms indoors and then replanting into those same pots because no one wanted to move them out of the mom room, now we have root aphid. There's a lot of things to consider there. For some people, moving from a 20 gallon down to a ten at first and settling on like a five is usually kind of where they end up. If you start shortening your veg practices down from, let's say you're going for four to six weeks now, down to two.
Seth [00:31:14]:
Okay, now we're looking at moving into a smaller media so we don't have to spend as much time allowing that plant to grow and take over that media and actually pull water out.
Jason [00:31:23]:
Yeah. What we're saying is especially true if you're using synthetic nutrients. If we are in a truly living soil, an organic situation, where we aren't using any salts as additives in our fertigation and everything, as amendments in there, you do need an appropriate sized biome to support the life of the bacteria and the microbes that are breaking down your organic amendments in there. So I would say just have that as a note of caution. If you are organic, there needs to be a sustainable sized biome down there. But obviously, if you're in a more soilless type of growing material, or if you are using synthetic nutrients, then that's the route I'd go.
Seth [00:32:13]:
Yeah, and you can get great results too. Like if you do have a really great mix, organic mix that you're using in the past, mixes that I've not invented but mixed up according to directions do include ingredients that give you a bit of ph buffering to really help you through that. That's one thing that when we're going with fully synthetic nutrients, just aka salts, there's not a lot of buffering capacity in there. And that's part of the point, right? This isn't deep water hydroponics, but we're still looking for close to that level of nutritional control over what we're giving the plant. And at that point, runoff becomes very important to maintaining that ph balance. When we've got a dynamic living ecosystem inside of the substrate that can come with better ph buffering, which can be good, can be bad trade off. You're going to need more media to give the plant the same amount of nutrition, which is going to make it much more difficult to steer vegetatively. So there's a lot of little things to think about in there.
Seth [00:33:14]:
And then finally, if you are trying to nurture a living biome in your soil, we're not going to go for those deep drybacks, because as you approach a drier and drier state, you're actually going to start killing off a lot of that good bacteria. It does have to have a certain level of moisture to survive in there. And if I'm trying to keep my microbes alive, but I also want to dry my coco down to 15 or 12%, those aren't really compatible strategies.
Kaisha [00:33:43]:
Oh, my gosh, you guys, thank you so much for that. Hugo, awesome line of questioning. We appreciate you so much for asking. Yeah, you're so welcome. Good to see you on the program. All right, y'all, we're going to keep the flow going. This question was submitted on instagram. Someone's asking, what's the procedure for flushing rockwool using tap water at 0.3 ec? I get it down to 0.3, but then it starts stacking again and ends up at 0.8 to 1.0.
Kaisha [00:34:13]:
Trigger warning.
Jason [00:34:16]:
Yeah. The first thing here, actually a really good question. The first thing here would be get a water test, try to get a water quality sample out and see what is in the tap water because we could be at a lot higher ecs in that Rockwool based on tap water. And as long as it's things that are good for our substrate, let's say it's just high in calcium, it's just some free nutrients coming out of the tap right now. If we're running into things like sodium chloride in there, then we're definitely going to have some issues at those levels. I probably wouldn't get too concerned, depending on what your water quality test is, because we're going to add nutrients in there anyways. Right. A lot of the cocos that I've worked with, I'll see them between, say, 0.6 and 1.2 ec just right out of the shipping crate and doesn't really affect it as long as we get a balance in there.
Jason [00:35:15]:
So the really important thing here would just be knowing what is making up that EC that you're seeing.
Seth [00:35:22]:
Yeah, absolutely. And if we're talking about trying to get that EC down in your actual rock wall, like we're flushing out or trying to flush towards the end of the cycle, that is one important thing to think about. Just what Jason just brought up with tap, you are still putting Ec in. It's not a zero or zero zero one Ec like we'd see with Ro. So when you do that, I guess let's just call it a mechanical flush, but your big flush, that's pushing everything out. If you resume a normal irrigation strategy the next day just with that tap water and you're not pushing a lot of runoff. If your plant really has stopped feeding and if you are pushing your EC down this low, you've taken out everything and forced it to stop feeding, basically because calcium doesn't do anything on its own, we're going to see that stack back up. Unless you're pushing a lot of runoff because you're just continually putting it in and not pushing it out the bottom.
Seth [00:36:13]:
That being said, we've talked a lot in the past about not being too obsessed with flushing and maintaining good, healthy zones for your plants. And then a big part that's come into that, we're hitting a point in technology where we've not only technology, but just good data across all the growers out there, where we've identified, like, hey, nutrient composition actually does matter to certain strains. Some strains are, I don't want to say really picky, but very sensitive to the presence of certain elements at certain points in flower. So where if I was years ago, running a different setup, and I'd say, hey, I need to flush these plants, maybe there's a different product or a slightly different mix that I need to run on that particular cultivar to get it to perform the way that I want to.
Kaisha [00:37:04]:
Fantastic, you guys. Thank you. We're actually getting a lot of questions in about EC official loyal to the soil. Dropped this on Instagram. They write, what's the ideal EC for flower without overdoing?
Jason [00:37:19]:
Know, this question could be asked and answered in so many different ways. From the perspective that we take every day, we're looking at continuous time series data of the EC, the ritzone. And so when we advise people and we help them start to optimize the crop steering they're doing for specific strains, there's going to be a huge variance in what that EC is from at the time of irrigation to the peak at the lowest point in the dryback, right at the highest point in the EC, the lowest point in water content on that dryback. And so I think for sacking, we're usually talking about ranges of that substrate being up in the seven to 1214 range. And then for vegetative bulking, I usually like to be between, say, five and eight for the EC.
Seth [00:38:18]:
Yeah, and this is a highlight, usually with a feed EC of between 3.0 and 4.0 on most nutrient available or most nutrient brands out there, typically that's just kind of a level that allows us to continually stack salt in there, start to build that up. And one really important consideration to make is how EC is one of the legs that holds the table up in terms of plant health. It's very important. What are my other factors doing? Because I can run super high EC and still successfully harvest a plant. But now there's a good chance that plant caused me more stress and cost more money in fertilizer than it needed to if I was limited on, let's say, co2 and light or airflow. So that's another really important consideration. Let's just throw it out there. I've got a twelve foot high ceiling.
Seth [00:39:10]:
Let's say I got my 1000 watt double enders strapped to the top and I've got three foot tall tables or three and a half foot tall tables off the ground. At my average canopy height, I might not be getting 1000 or 1100 ppfd. If my PPFD is way back down at 700 on average for the room, let's say I'm not going to need to run quite as high of EC, nor am I going to need quite as much co2 or quite as much water because the plant is just not consuming all of it. On the flip side, if we are pushing those values higher and higher and higher, especially when it comes to PPFD, then we're going to start to see the need for more Ec. And then beyond that, we're starting to look at if everything's optimized, even spectral differences, not just between LEd and hps, but what kind of spectrums are your led lights actually running? Because we see quite an interesting variety across all the different manufacturers, some of which have their own issues or non issues, the way you look at it. But different spectrums can also affect EC usage and uptake.
Jason [00:40:14]:
Yeah, hopefully I'm going to dive into assimile here for crop steering. Right? And we're going to talk about different strains and how they respond to different steering tactics. It's really, really important when we're making these recommendations. It's like, all right, middle of the road. If I know nothing about how this train behaves, here's what I'm going to do to approach it. Right, so let's say we're doing some crop steering in a go cart. We're obviously going to be doing a lot different type of inputs than we were if we're driving a monster truck. And so when we're thinking about, all right, how does this strain behave, the best things that you can do is, one, make some documentation on how it's performing, how is it reacting to the environment in this case, especially the nutrients and the regiment that I'm applying to it.
Jason [00:41:03]:
And then two, make some analysis on what you're seeing from that plant response. So that's really important to kind of identify that, hey, we're talking about driving a Honda Accord or what's the most popular car these days?
Seth [00:41:18]:
Oh, geez. A kia.
Jason [00:41:20]:
Oh God.
Kaisha [00:41:21]:
All right.
Jason [00:41:24]:
Just not to try to get too cliche out there, but I felt like it was very representative. And when we even look at some strings, we can tell that, hey, this one is going to feed substantially different than another.
Seth [00:41:36]:
Yeah, I think one of the things to really think about when you're looking at EC is throughout this plant's life cycle, we're adapting its roots to live in this certain environment. And that's like one of the primary reasons that as we've gone into coco, rockwool, these truly soilless medias, we do want to get away from flushing, because if we're only giving it those inputs and the media doesn't have any buffering capacity on its own, if we're wildly adjusting that root zone EC from a six one day to a 1.2 the next day, because we flushed it out and then trying to stack it back up, we're really wasting time in production because the plant actually has to take energy and put it towards either consuming sugars in the root zone or stocking the root zone with sugars to help adjust to that osmotic pressure change. So when we're looking at different ranges, there certainly are ideal ranges with certain strains in a specific growing setting. However, even if we looked at, what's that optimal range? All right, if I looked across the population of one of the best rooms I've ever seen on a given strain, if I went and stuck pots around there, I would see a little variation. If I was targeting seven, I'd see everywhere, from a 4.0, probably up to a 9.0 at my wettest point across the room. And at that point you go, okay, I have this variation. What is optimal might actually, actually just exist in a range. It's not exact.
Seth [00:43:01]:
And I've got to manage EC across all these. What's the safest thing to do at the end of the day, to make sure my crop makes it through with good health. That's to just have the control to be able to maintain those EC ranges and not have it immediately drop out or spike up all the time, because that can also affect your ph. And I mean, the more you radically shock a plant, which drastically changing the osmotic pressure in the root zone is a pretty radical shock to the plant, the more adverse health effects you're going to see and worse results you're going to get. So, as we always say, notes, pictures, really pay attention to everything that's going on, so that you can also try to identify, like, hey, did this strain, like, running at a higher EC? Maybe? Were we able to maintain ph throughout that whole run? Or did we stack up EC in the first three weeks without pushing runoff at the expense of lowering our ph? And that's why we saw some perceived lockout or burning. Let's know, looking back at the data, it might suggest that, hey, the EC level was fine, we just didn't manage ph. And that's why we're seeing these results. Rather than saying, oh, we had too much or usually too little EC, we often see characterized by light yellow growth in new parts of the plant and classic deficiency symptoms.
Kaisha [00:44:20]:
Thank you, guys. I feel like the theme for this show is take notes lesson that we come back to often. Appreciate that question. Good luck. Official, loyal to the soil. All right, we got this question in on YouTube from six one eight grow. They're wondering, what week should I start? Drought stress and cooler temps.
Jason [00:44:43]:
I mean, one of the first questions that I would ask is do we want to be applying drought stress? Certain strains are going to respond slightly generatively and actually have a good response to drought stressors. Some really don't like doing drought stressors. And so when we're talking about the typical drybacks that we recommend, we're actually really not even usually getting very close to any type of drought stressors. So in rockwools, in coco, we're not applying a drought stress when we're at, say, 20% water content. And what's going on there is we're usually using an osmotic potential to indicate some of these cues. Now let's say something like coco. If we are getting down to 10%, 12%, we are going to see some amount of response to the plant based on a drought suppressed stressor. And really what we're using to analyze this is what's called matrix potential.
Jason [00:45:36]:
And matrix potential, the simple way to think about it would be how much vacuum does the roots have to apply on the substrate in order to pull water from it? And the different characteristics of different minerals in a substrate cause those matrix potential curves to look substantially different. In something like rock wool, we're usually not even going to see a drought stressor until the substrate is below 5% water content. And so I guess that would be kind of the first question. Are we pushing these plants very extraordinarily generative? Then? Yeah, let's do a drought stressor. As far as to answer at what weeks, it is extremely strain dependent. When we talk about middle of the road, like I was mentioning earlier, we'll talk about, say, three weeks of generative stacking at the beginning of the cycle. I know we've said it in probably almost every episode, that on one side of the spectrum, you're looking at plants that are already generative leaning, and we may not have to do very much generative steering, and we can just apply bulking, maybe even after week one, maybe we actually don't even do much generative at all. And then on the other side, if we have plants that are genetically vegetative leaning, then we might just run bulking through the entire cycle.
Jason [00:46:54]:
And that's one of those things where we have to analyze how does this strain respond. And so, yeah, let's start with the middle of the road. If we know absolutely nothing about how the strain grows, take those notes, analyze. All right, this is what we saw in response to that, and then manipulate your application for the next run and go from there. Continuous improvement.
Seth [00:47:17]:
Yeah, I mean, I think a lot of this just really comes down to your media and that term drought stress. We don't ever actually, not just to me, but we define drought stress in greater agriculture and science. What that's talking about is becoming really close or actually crossing the line, that is temporary wilting point. So one thing we're doing with the media choices that not just arroyo recommends, but people choose for indoor cultivation in general, is pick one, both coco and rockwool, for instance, being the two most popular, probably followed by peat moss right behind it. One beautiful thing about all of those medias is they do have a fairly low matrix potential, which means our temporary wilting point is quite low. And what that allows us to do is dry it back a lot farther than maybe more traditional soils laying out on the ground before we actually get that drought response, which is wilting. Anytime we put the plant into a zone where we're truly applying stress that would affect the plant's health, that's usually pushing it a bit too far. We're losing productivity time if we actually have to slow down the plant, right.
Seth [00:48:21]:
Because if I'm pushing that too hard, too low, if I'm flirting with temporary wilting point, the plant's response is to shut down its stomata and try to reduce transpiration. If that's happening for that 1st 2 hours. One morning when the lights come on, my plants start to droop a little bit. My stomata close up well over a few weeks, I've just lost 2 hours per day of production time that would allow my plants to grow or produce oils or anything like that. When a plant's in drought stress, it is not actually really producing anything. It's trying to go conservation. It's trying to be as conservative as possible and attempt not to dry out all of its leaves by transpiring too much too quickly and wilting itself. So I think that's one of the really important things to look at here.
Seth [00:49:04]:
And just like Jason said, we see a huge range of responses among strains and usually the best protocol I like to start with. If I know nothing about a strain, I'm going to try to run it nine weeks because I'll give it a fighting chance. If it goes longer than that, I'm probably not putting into commercial production and then minimum three weeks. Usually I'll start out with four. If I've seen the plant in some other grow, that can still help a lot. If I have an idea of what its stature is going to be like and any info you can get from another grower, it might not all translate to your grow, but it can help. And then you can decide conservatively. Hey, for me, I like really simple three, three and three.
Seth [00:49:42]:
When I'm baselining a strain like, okay, I'm going to start out with three weeks generative as the plan going to go measure it, see how my stretch is doing. When does it actually finish stretching? Take notes so next time I can modify it and say, okay, this one actually stretched to day 24, not till day 21. I'm going to adjust my generative dates on the beginning and then start out with three weeks of ripening. Now, one thing I know doing that is I'm probably not going to maximize my yield with only three weeks of bulking in the middle on a nine week run. But I'm probably, and by probably I mean I really haven't found a situation where this didn't work out. I'm going to avoid over bulking that plant and lowering my flower quality. So step one, I'm going to go into being able to see like, hey, here's what these two irrigation strategies did for me, but I'm leaving plenty of time on the end to ripen up. That way I'm still getting the potency and look that I'm going for.
Seth [00:50:34]:
And then, hey, we can start to open that window up over time on successive runs and establish like, does this plant need a week to ripen? Does it need two weeks to ripen? Is it some old school Oreos or cookies and cream where you can pretty much bulk it right up until the end? There's a whole spectrum out there and in my experience with the amount of, what's the word? I don't want to say undocumented crossing. But due to the fact that it's actually really hard to trace some of these lineages in cannabis, and there's also a lot of variety and variability within these genetic lines, it's really hard to say outside of broad generalizations like, hey, this is a runs cross. Here's how it's going to behave. Right?
Jason [00:51:19]:
Yeah. It's amazing to me how sometimes crosses don't act like either of their parents at all. It's just totally outside of expectations. When we say things like strain dependent, we're talking about it all the time. We're not trying to have a scapegoat on how to get away with this. We're trying to get you guys the best information that we can. And a lot of the work that we've been doing actually recently, especially in the last six months a year, is trying to enable breeders and clone suppliers to be able to help you with this information. Right.
Jason [00:51:52]:
So most any of the good suppliers that you're getting this stuff from have done some flowering experiments with the supplies that they're getting for you. And so you can ask them, get some personal experience from them. It's going to probably be a lot more detailed than what we can just roughly talk about without knowing what strain or what your goals are. And then definitely one of the things that we are doing is trying to help get the aurora into the breeders experiments as well, so that they can just supply this information. How did they achieve the best results from this specific strain? And they can include that with their stock and actually increase the value of that stock not only for them, but increase the value of it for you and the potential for your sales output.
Seth [00:52:38]:
Yeah. That way, when you go through your first run, you look at the finished product, you at least have the instructions on everything they did to achieve that. And I don't know, Jason, in my observation, working with some of these guys, over time, breeders are moving more towards standardized production procedures in efforts to help their selection process to produce better results for most clients. Right. That's one thing that is pretty well currently very specific to cannabis horticulture in general is every other part of agriculture. We've got 100 plus years of plant breeding. That's really helped focus on traits that make these different varieties really easy to cultivate commercially. If we could fast forward 20 years right now, I can guarantee you'll be able to find a lot of the versions, a lot of strains that you like.
Seth [00:53:31]:
In a version that is betritis resistant, in a version that is fusarium resistant. Now will they be 100% resistant? Maybe not, but we will see designer strains, essentially, or varieties at that point that are trying to solve some of these problems with genetics, which we know if you've grown enough different strains, especially if you have some suboptimal growing conditions, you've been screening for mold for years. And so, you know, every once in a while you get a winner that comes through. And just like, even when everything else molds out in that room, that one doesn't. And we're just not quite there with the genetics yet in terms of, well, the industry is just getting kicked off right on a grand scale, so it just takes time and money and looking at like, hey, to isolate some of these different genes, we might be looking at a few years of research going into this one line and then figuring out how to introduce those genes into other plants via breeding and how quickly that can happen. So, like, if I've got mold resistance, for instance, and it's a recessive trait, I've got to isolate that into a line that I can then go cross it in and back cross and make it available in the line that I want to. That doesn't happen tomorrow, but it is coming down the road. We're just in the infancy of that.
Seth [00:54:42]:
And that's part of why this is such, all these strain specific requirements are part of what makes this fun and I think also part of what keeps cannabis growers so engaged. I've worked in bigger egg. I haven't met a wheat farmer who is nearly half as passionate about wheat as any cannabis grower I've ever met. To be honest. Those guys might be passionate about running their business or having a sustainable component to their farming operations. They're really into soil health or conservation. But rarely am I going to go out and meet someone that's in field agriculture. I like to pick on wheat just because I could look out the window and see a bunch of it here.
Seth [00:55:25]:
But they're not as concerned about what is that variety they're looking at, hey, how easy is this to grow? How does it yield? Am I getting the protein content numbers to really get a premium on my crop? That's it. Whereas with cannabis, we get a lot more little problems to solve and just a lot more passion in general. And I think that's part of what attracts a whole set of people to this industry is it's problem solving day after day after day. Even if you take out the weed part, make it not cool, you're still engaging mentally with some of these problems that are just like they're not intuitive. Some of them are really difficult to really wrap your mind around and it takes a lot of time and energy input to get there.
Kaisha [00:56:06]:
We really are just getting started. Are we? Sorry to cut you off, Jason, go ahead.
Jason [00:56:09]:
Oh, you're all good. One of the fun things, I always have anecdotes from the early days of when I was getting into some boutique grows and I was asked, what is your favorite part about going to work on a daily basis? And it seemed like the overwhelming response was popping seeds or breeding.
Kaisha [00:56:33]:
There it is. All right, I got a question here. Want to get to before the end of the hour? And I got an announcement at the know. I love to drop announcements. All right, this one came in from Instagram. Rocketbud Farms had a question. They're dealing with a situation. They're wondering how much ac, btus or kilowatts do we need for 1000 watts of Led? I have 8 leds and only 24k btus, but I can't go below 85 degrees fahrenheit when lights are on 100%.
Kaisha [00:57:06]:
It's my new room that I need to get up and running in a few days. And now I'm trying to calculate how much I need to add. Room is 400 cubed and I use acs only for cooling and heating. I have separate 2 humidifiers. Rooms are sealed and co2 enriched. Thank you so much. If I need to drop any more of those numbers again, let me know.
Jason [00:57:31]:
Yeah, I'm not going to do the actual calculations here in my head. I want to make sure that we get you the right answer. But the approach here would be, obviously, if you want to know how much heat that LEd is adding to the room, then I think what one watt is like three point something btus, if I remember right. And one of the things to consider is what the efficiency of that LEd is, right? So 1000 watt light isn't going to put 1000 watts of heat out there. Depending on the manufacturer of those leds, have a reasonable, decent efficiency. Right? So get an idea of, all right, am I adding 300 watts of heat into that room? So that's going to be how much btus we already know we have to get rid of. So that would be the first calculation I do. The second calculation would be what's the temperature offset that I need to achieve? Right.
Jason [00:58:23]:
And so we have to add that in our BTU capacity on top of how much we're adding in there. So if our lights are off and we need to be at a ten degree lower temperature inside this grow room, than outside. Maybe we're down in Arizona or something. Then that's going to give you an idea of how many btus per hour that we need to inject into the room in order to maintain those temperatures.
Seth [00:58:47]:
Yeah, not make me pull out the books. I love having Jason here. One little hint on that. Depending on what fixtures you're using, a lot of people have already done a lot of these calculations and you can go search like, hey, what's my average BTU output per hour on 1000 watt HPS on x amount of wattage led and that'll put you relatively close. And then when you're looking at upgrading your system, especially with, I'm glad you included 400 square foot room, don't overshoot your upgrades. So I've run into that situation, particularly with D. Hughes and acs before, where people are making a little more money. They're adding some lights to their room.
Seth [00:59:26]:
They're really trying to pump it up right? They're like, hey, we used to grow at 600 ppfd. Now we're going to get the capacity to grow at 1000 in here. One of the biggest mistakes they'll make is going and scrapping their old small equipment and then doubling the size and putting bigger units in. And now they can't affect change at a small enough level to keep it in the ranges they want. So anytime you are increasing that ac capacity, if you've already got an installation where you're like, hey, this gets us almost there, instead of calculating your BTU needs and saying, hey, I'm going to get one unit that'll take care of all that in a 400 square foot room, looking at maybe adding a few mini splits or something that you can phase out a little bit more to give yourself control.
Kaisha [01:00:09]:
Wonderful indie buds, good luck. Thank you so much for your question. All right, before we go, I just want to let you all know we are giving away, I don't know. Have you heard this month, if you want to enter it away, you just visit cloud Adam IO aroya giveaway I'm going to drop this in the chat. Get over there so you can win you in a way to go. Good luck out there, you all. All right. And then one last thing.
Kaisha [01:00:33]:
We did a quick poll on YouTube. We wanted to ask, are you med grower, rec grower or both? We've got 14% EC growers and 86% are both. So we appreciate you. Thanks for all that you do. As a consumer, I'm certainly grateful. All right, thank you guys so much. Seth and Jason, Chris, our producer, thank you so much for another great session. Thank you all for joining us for this week's Aroya office hours.
Kaisha [01:01:00]:
Live. To learn more about Aroya, book a demo at Aroya IO and our team will be happy to show you the ins and outs of the ultimate cannabis cultivation platform. If you have any crop steering or cultivation questions you want us to cover, drop them anytime in the Aroya app. Email us at sales, send us a DM on Instagram, Facebook, or LinkedIn. We want to hear from you. And if you're a fan of the pod, be sure to subscribe on our YouTube channel so you never miss an episode. We'll see you at the next session. Thanks everybody.