Subscribe
Share
Share
Embed
Seth Baumgartner and Jason Van Leuven open the mics for your crop steering and cultivation questions.
Kaisha [00:00:02]:
What's up, gromies? Welcome to Arroyo office hours, your source for free cannabis cultivation education. I'm your moderator, Kaisha, and this is episode 112. Shout out to our live viewers on YouTube and Instagram, to everyone tapping in on Spotify, Apple Music, YouTube, or wherever you listen to podcasts. Thank you so much for your support. If you like the pod, please do drop us a review. We really appreciate your feedback. Seth is back in studio. Seth, how you doing?
Seth [00:00:27]:
Good. How are you, Kaisha?
Kaisha [00:00:28]:
I'm good. You ready for our first question?
Seth [00:00:31]:
Yeah, let's jump in.
Kaisha [00:00:32]:
Awesome. Let's jump in. This is from our good friend Dave Ray. He dropped this question and some visual aids. So I know producer Chris is going to pull those up in a second, but they've got a screenshot of their Arroyo graph and they asked, just curious, your take on why one of these strains. Blueberry muffin, a shorter squatty plant, generally low stretcher. We see the EC remain level starting at 4 hours before lights off and throughout the night cycle rather than rise like the other strains that we've been seeing. Dry back is about 30% volumetric water content.
Kaisha [00:01:06]:
All plants look healthy. All strains in the room show some slight tip burn. Nothing major at all. This is week three of flower cocoa, one gallon, 3.5ft. EC junior crop tech 5.5 to 5.6 ph per their recommendation. So, yes, doctor Seth.
Seth [00:01:27]:
So a lot of times when we see that EC not rise dramatically overnight, we're looking at the plant uptaking salt. Because as that water content's going down, if the plant wasn't pulling any salt out, we would see that EC rise much more quickly, like in the top line in this chart here. But when we see it flatten out, typically that's just a sign that the plant's a heavy feeder. And if I was watching those plants, I'd probably start looking at my runoff samples to make sure that my ph is staying in range in the runoff. Otherwise, it's not a bad sign at all. It just means that plant uptakes a lot of nutrients. And that goes hand in hand with a lot of squatty plants. Actually.
Kaisha [00:02:04]:
Shout out to Debra for growing one of my favorites, too. I love some blueberry muffin, but yeah, beautiful. Look at those girls. Awesome. Thank you, Seth, for that. Dave Ray, keep us posted. Good luck. All right, we're going to keep it moving.
Kaisha [00:02:19]:
So we got this one from Checkwild 4208. They are a new Arroyo user. They write that they just set up, just set up my arroyo this morning. How do you set alerts for low water content and high ec. I have an open sprinkler coming in the mail. Just trying to figure out how to get both systems to work seamlessly together for irrigation. I have a four by eight table in my room, two and eight bar led lights. I run an open loop system drawing air from under the house.
Kaisha [00:02:45]:
It works great. It can be 115 degrees outside and only 86 degrees in the room. I'm in late flower week. Seven out of ten. My room temperature ranges this time of 84 to 70 degrees and 35% to 40% humidity. Some days they are fine with a 23 hours dry back. Some days they dry out before that. I hand water at the moment setting up my drip system this weekend.
Kaisha [00:03:09]:
Just got open sprinkler in the mail. I know I can set alerts for low water content, and Arroy has the ability to talk to open sprinkler and water for a set program. What kind of ideas or strategies or programs do you suggest to handle this problem? So why don't we start there?
Seth [00:03:26]:
Yeah. Unfortunately, I feel blindsided. I should have my laptop in front of me to screen share. But depending on whether you have Arroyo go or Arroyo core, there's two different ways to set alerts in your system. Number one, with Arroyo Core is through the recipe in the harvest group. That allows us to set progressive alerts that change over time to match the target ranges we want for a specific time. And then in Arroyogo and Arroyo core, we have the ability to set alerts at the room level. There's a couple different theories about how to set alerts.
Seth [00:03:57]:
Personally, when I'm looking at something like irrigation data, for instance, if we're talking about water content, if I had a media rockwool coco that got up to, let's say, 65% vWC at field capacity, I know that I might be pushing anywhere from a 20% to 30% dryback, depending on the media, possibly more. That being said, throughout those first three weeks, we're gonna see that dryback grow day after day, get deeper, and be adding more and more volume to our irrigation, and possibly more time in between those shots throughout that time period. So as those plants are growing, I want to make sure that I'm replacing that extra volume and then really adjusting what ranges I'm running in based on the media, and then, you know, setting alerts in a way that are actually actionable. So if I'm targeting a dryback that goes from 65% vwc down to 30% vwc, if I have a plant that goes down to let's say 28%. If I'm looking at that graph every day, you know, essentially what I'm doing is looking what happened yesterday? How far back did we dry? What was the rate of dry back? Does it look like we're going to repeat that today? And if so, judging by what happened yesterday, do I need to add water to make sure we're not going to dry back even further? Now, if it's like I said, you know, 30% was a target, we're going to 28. I probably don't need an alert for that because I'm going to go check that the following morning and see that, hey, I need to add a slight bit of volume, you know, maybe one, 2% sent to one shot or to all four or five in my p one series to achieve that field capacity. However, what I want to get an alert for, typically is an actual equipment failure or action item. So if my target was 30, I'm going to set that alert way down at something like 20.
Seth [00:05:42]:
Because also, if I'm running cocoa or rockwool or I just have plants that are different sizes, I know that all these things are going to exist within a range. And I don't want to get alert overload where I'm getting, you know, an alert every 20 minutes for ten different rooms about something that I'm taking care of every day. Anyways, the alerts that I get, you know, using temperature as an example, for instance, if we set a, you know, an analytical target range that's 78 to 82 for a given time period, maybe my system handles that. Well, maybe I can't maintain that dead band. I actually have, like, an eight degree deadband. Well, if that's the case, I don't want to have my alert set that every time it goes past my perfect dead band, I get an alert. So I'll set that. You know, if we're talking about temperature, you know, my.
Seth [00:06:26]:
My own personal growth, I have an 80 to 82 target range that I'm looking for. I'm not going to set an alert until it goes below 70 degrees in early flower, for instance, or above 90, because one of those, the low end, would indicate that any heat source that I have in the area that I grow is not working correctly, just basic h vac stuff. Or on the other hand, if I'm, you know, going over 90 degrees and somehow it happens to be over that outside in the northwest, um, that means my ac is probably not working and the room's not getting cooled the way it should. Either way, if I'm within those ranges and nothing's broken. I'm going to look at that chart and adjust those set points because I set these in a range where I'm not likely to hit either of those extremes. But if I do, that's a point where I can still take action and fix the problem, not a point where I've actually, you know, experience crop loss.
Kaisha [00:07:20]:
Awesome, Seth, thank you for that. We also have a link that we're going to drop, sharing more information about our open sprinkler integration. Sweet. All right, well, Chuck Weil, good luck. Let us know what's going on and hit us up anytime if you have any more questions. All right, we're going to keep it moving. We got a two part question from Chili Wolf. I'll start with the first part they wrote from last week.
Kaisha [00:07:42]:
Jason helped me realize that Hugo blocks alone will likely be too small, decent ripening stage drybacks. So I can either increase plant count or change substrate size. If I was to veg into three by three Grodan first, then stack onto the six inch Hugo a week before flip, would this help, or is the three by three block still not much of an increase? I'm kind of aiming for five ounce plants dry, which I think. Which I definitely think too much for a hugo alone. What do you think?
Seth [00:08:16]:
Yeah, I mean, that's. That's something we run into quite frequently. You know, the volume in a Hugo block can only support a pretty small plant if you want to be able to go generative at the end. And also that's provided you were able to maintain your water content high enough that you didn't experience any drop in field capacity throughout that time. So there's kind of two things working against you. If you have a plant that's too big for the block, it's likely going to dry it down too far below about 35% vwc. And that's where we'll see, you know, the development of hydrophobic pockets and part of the Mediaev, which if you can only get the media back up to, let's say, 45% vwc and it was at 55 before, you've effectively lost 10% of your pot size because you lost 10% of your water holding capacity. And part of the issue with Rockwool or any other potted media is if we look at a regular cube of a pot, a six by six by six, anytime we're looking at a media, whether it's cocoa, peat moss, or Rockwell, we actually have a little bit of a gradient.
Seth [00:09:19]:
So up top, just because gravity exists it's constantly pulling the water down. And we have a perched water column. So anytime we're looking at it, we go from a concentration of less and less water all the way down to a higher and higher concentration, until we hit the point that cohesion is overcoming gravity and holding this essentially pool of water and the bottom of the media. And when we're talking about plants themselves, we have a plant coming in, we've got roots going down. Your roots actually absorb water through root hairs on the last, like, small tip section of the root. So all of our water absorption is actually happening in this perched water column right here. So if we, for instance, put a three by three by three, or four by four by four, or a four by four by two and a half on top of here, we're not actually increasing the functional capacity of the media that will help us hold water in the place where we want it for water uptake. And that's why we see, like, let's pretend this was actually a four x four x four.
Seth [00:10:22]:
The implementation of something like a slab or a unislab, where when we put the slab down here, we're actually increasing the area of high water holding capacity that the plant has access to. In fact, if I somehow built a media, which is possible through different densities, to hold water up top, right here in the higher portion, that's likely going to produce poor plant growth, because the roots really need to get down to the bottom of this, of the substrate and absorb water in this area. So that's, that's why, uh, we see, you know, a lot better success with something like a 36 by six inch by three inch tall slab or something like the Uniswap, because we're actually increasing the effective absorption area that our roots have access to, where if I just, for instance, stack that three by three on top of a six by six, I'm not really increasing the water holder holding capacity of that media, because I need the media to be wider at the bottom, where it's actually going to collect a lot of water. So Hugo's, from a production standpoint, or any other six by six by six media or smaller, do seem great for efficiency, right? We drop a clone in all the way through, but a lot of strains won't respond correctly in terms of producing a quality plant because we're generally forced to bulk it. The margin for error on overdrying those small containers is very risky when it comes to Rockwool, because we will hit a point where if it has been overdrive, that field capacity is down you might have to give it 10, 12, 16 irrigations per day just to keep the media wet enough for the plant not to wilt. And at that point, we're not able to apply any kind of generative stress or strategy to this plant. So when faced with a situation like the hugo's, the next question is how big of a plant can that support? And a lot of times we're looking at, you know, a three, maybe four foot tall finished plant, but highly, rarely, and with, you know, a pretty small structure. So you can always, you know, flip your plants really small.
Seth [00:12:28]:
You know, we do have a lot of, uh, double tier growers out there that are in that situation where they only have 4ft of space from the bottom of the tray to their light. So they are targeting a very small plant size. And at that point, we're dropping a clone in and going with, you know, a ten day max veg, basically get roots and flip, because doing everything we can to keep that plant height down and not have to go in and tuck branches into trellis. And at that point, there's a certain balance between how much, how many different medias are you buying? So what's the total quantity of pots you have to buy for your plants to get the same yield? And I think as producers, we're always chasing that balance between how much total quantity of materials do I need to produce a certain yield and then balancing that with, if I go heavier on the materials, can I cut down on production time, aka less time and veg, or, you know, less time in veg, more plants, we get them through the system quicker. So that's, that's always a balance to look at, but usually moving up to a slightly bigger media, more in the one gallon to two gallon range. If we're looking at, you know, total volume, uh, is kind of the sweet spot between giving yourself some margin for error. That way, if you ever have any kind of equipment failures, power failures, etcetera, you're not necessarily losing half of your yield because of one or two days downtime on a certain piece of equipment. And you're also giving your plants the opportunity to get bigger and be able to apply that ripening pressure so that we get better overall turp and cannabinoid expression in the end.
Kaisha [00:14:01]:
Amazing. Thank you for that overview. All right, let me drop the second question that they had on this topic. So they wrote, if I was to stack a three by three on top of a hugo, do I then add the field capacity of the two blocks together to get total field capacity? So I can work out shot size. And how does this affect dryback percentages? For example, would a sensor in a Hugo alone give a different percentage dry back at, say, 50% field capacity, as opposed to the same amount of water volume in a three by three stacked on a hugo? Hope that makes sense.
Seth [00:14:36]:
Yeah. So let's go back to the drying here, because I already made a bunch of little squares and rectangles. So if we put that three by three on top of the hugo, now that these two meteor contacting, if you put it, if you hydrated this to field capacity and let's say, got 55, 60%, and then place it on top of this block, you would see within about ten minutes, this field, this water content, where you have the sensor inserted into this three by three drop from, let's say, 60 all the way down to 25 or 30%, because now that it's in contact with this media, that water is moving downward. So to calculate your field capacity, you would add the volume of this block to the volume of this block to get total volumetric water content. But because this block essentially is leaching all the moisture out of this block, this area down here in the bottom half of this hugo is ultimately what's really important to us. So, I mean, you know, short answer. Yes, you can stack this intermediate block, a smaller one, on top of the hugo. However, if you're going to finish in the hugo, there's not a whole lot of advantage to that, because in the time that you would, you know, veg a plant in the hugo to get as big as you would want it to get in this, this pot, a smaller pot, you're probably already outgrowing the max size that you can grow in that hugo while being able to still go generative.
Seth [00:15:56]:
And there are strains out there that respond just fine to growing in a pot too small. They're super generative, leaning naturally. But that's not all strains, that's for sure. So it kind of depends on what your goals are, what your space provides, and, you know, what kind of materials you have access to. If you have a local grow shop or distributor that you're working with, supplier that can let you try out some slabs, especially if you're already on vegging in something like the three x three or the four x four, really encourage you to try out the slabs if you're trying to grow bigger plants. If you're in a double tiered, really height limited situation, then the Hugos definitely can work for the smaller plants. But if that's not the case, usually we see a lot better quality coming out of going to a little bit bigger media and going with a little bit bigger, more spaced out plants rather than completely packed in very small sea of green style plants.
Kaisha [00:16:52]:
All right, Chili wolf, you heard it. Good luck. Keep us posted. Thank you so much for those great questions. All right, going to keep it moving. Got a couple of other live ones here. This one came in on YouTube. Starred eyes is looking for some guidance.
Kaisha [00:17:06]:
With high ceilings and a metal indoor facility, what is the ideal nighttime temps to allow transpiration before irrigation to assist in aspergillus growth besides moisture dripping on plants, wanting to keep a beneficial diff to allow for a healthy chunk and no mold, what advice would you give to start?
Seth [00:17:27]:
Yeah, so when we're looking at overnight temps, you know, really one thing we're targeting is that ten to 15 degree overnight differential to really promote that purple expression, better terp profile and production, and generally higher cannabinoid content. However, that always comes at, you know, what, the cost of what is a facility, the limitations of the facility. So there's different strategies on ramping down temperature at night to help balance humidity out, turning your dehumidifiers on before lights go out to try to let them get ahead of that temperature drop, which is going to really spike relative humidity, and then establishing a set set of rules. So, you know, when we talk about like aspergillus and botrytis, for instance, it's very difficult and expensive to build a grow facility that has like, a surgically clean grow room where we can guarantee we're not dragging in, you know, any kind of contaminant from the outside air. And, uh, you know, very few of us live in a place where it's completely impossible to grow something like an apple tree, any kind of fruit tree, nut tree or vegetable production. You know, summertime pretty much everywhere, there's gardens around, there's fruit trees growing. So things like aspergillus and botrytis are, you know, they're ubiquitous to the environment. So what that means is we have to kind of establish some hard rules on, hey, where does the, in what ranges does this mold grow most prolifically and in what ranges? And how can we manipulate that to avoid that? So when we're talking about things like aspergillus and botrytis, particularly once you go below about 70 degrees Fahrenheit, they bloom very, very well.
Seth [00:19:02]:
That's their prime growing conditions is like 55 to 70 degrees. So once we're inside of that temperature range, we also have to look at, okay, what are the humidity or VPD requirements for that organism to grow. And typically, we see anytime you're dipping below a 1.0 vpD, which at, you know, 65 degrees fahrenheit is about 43% to 44% humidity. If that humidity is rising above, let's say, 45% in that scenario, now we're in a zone that we're at risk for mold spores germinating and effectively growing. And then on top of that, we've obviously got plant health. If we're not coming into those last two weeks with healthy plants, they are more susceptible to mold. But really, you know, managing that dew point. So we're not getting any rain on the plants because it's very difficult from a h vac standpoint to dry off plants that just got rained on inside of a controlled environment, we don't have wind and sun to help us out.
Seth [00:19:58]:
Really watching those points and then, yeah, watching those ramp up and down times to make sure you're not getting condensation on the plants. And if there's an insulation issue, a building facility issue, it's definitely worth looking at doing a little bit of cost benefit analysis to say, hey, we're losing x amount, whether it's 510, 20, 30% of our crop every time to this mold, and it's because it's raining. Okay, if it costs $50,000 to fix the insulation issue in this room, how much product do we have to grow, really, to pay that off? I think a lot of times when you're running into issues like this, you know, really what we're up against is we're out of h vac in the room. We can't. Can't decrease the humidity anymore with the available equipment. And once you hit, you know, two thirds of the way through a run, it's, you know, budget aside, it's still difficult and costly to go install more h vac equipment while you have your plants in there, and you're also risking crop damage, introduction and contaminants, et cetera, by having a crew come in to install that. So at that point, I think another thing to balance is, hey, if we really can't reach those humidity goals and we look at, okay, what's our dehumidification capacity per light in the room if we're really low on that spec and, you know, like, kind of the old school HPS standard is 20 pints per light and much higher for led if we're already low on spec with the number of lights that you have, sometimes it is more cost effective to shut off a row of lights and not fill up a row or two of plants and realize that, hey, I can grow because that dehumidification capacity really is my limiting factor. These extra lights are kind of a waste of energy and time, and I'll be able to get better quality off of growing less plants in the room and operating within a plant population limit that my facility or my room can actually handle.
Seth [00:21:54]:
And we see that a lot out there. There's been a lot of learning done by pretty much everyone in the industry that's designing these facilities. And if it's five years old, I'm not going to say functionally obsolete, but we've made a lot of leaps and bounds, and there's a good possibility that it might have been under spec'd initially. Or, for instance, if, hey, your lighting has been upgraded, now you have the capability to push a lot more light into the room via leds or even upgrading just old bulbs on HPS. And now you can push a lot more light, which equals a lot more transpiration. That equates to a lot more humidity in the room. So sometimes, over the course of operating a facility, upgrading it, and refining your growing practices, you're actually just outgrowing your room. And you need to figure out if you've hit 100%.
Seth [00:22:43]:
If so, are we ready to make the upgrades, or do we need to, you know, work more around? We found 100%. What else can we do with our business and business model to make that 100% profitable?
Kaisha [00:22:57]:
All right. Yes. The wonderful world of pest management. Good luck out there, friends. Appreciate your question, and as usual, please do come back and keep us posted. All right, we've got a question here from someone named Seth, who's here on the chat. What's up, Seth? Welcome, gromy. They wrote.
Kaisha [00:23:15]:
Hey, guys, I'm noticing that certain genetics that I run specifically in the OG category start to yellow out around week five, mid bulk. It doesn't look like a nutrient deficiency to me. If I were to guess, I think it has to do with light intensity. Lowers are a healthier shade of green. Par is in the 950 to 1000 range, following front row AG feed chart 2.6 to 3.0 ec. How do you handle strains that don't seem to like a lot of light? At what point does reducing light intensity cause more harm than good? Does it make sense to wait until week five to make changes? Since all is well up to that point, any help is greatly appreciated, as is your question, Seth. Thank you.
Seth [00:23:57]:
All right. That's a great one, Seth. Thanks for all the info on that one. That's perfect. We got some strains out there that are definitely sensitive to higher, lower levels of EC. That definitely happens. One thing I do when I'm looking at a strain that particularly struggling with and hits these same symptoms at about the same time in every cycle is to go set up a substrate sensor in that get data for the whole run. But I also like to set that same plant up to collect runoff off of.
Seth [00:24:24]:
So I'm looking at that root zone EC and then the runoff ph from that specific plant. And what I like to determine is, especially for some of these plants that traditionally, excuse me, we've run lower ecs on, is there a chance that by running that lower EC, and especially if we're trying to build a little EC, restricting runoff over a lot of time has led to a slow decline in ph in the substrate? And one of the unfortunate things about measuring substrate ph is we're only getting it, you know, ideally at the end of that p one cycle, and that's a one point in the day. So if I've got a low EC situation in the root zone where I'm running, let's say three to five, right when I hit bulking, if I'm pushing 1000 plus ppfd, especially with a full spectrum led, I might be at the ragged edge of malnutrition on that plant. And even though I'm not seeing super deficient symptoms right now, that plant's taking, picking up almost everything I'm putting in every day, which leads to not necessarily a persistently low ph condition, but a low ph condition for a certain portion of the day. So if six out of 24 hours, that ph after the plant's been feeding late into the night, dips down to, let's say, 5.15.0. Now we're seeing as restriction and nutrient uptake for a period of time that although, you know, one day to the next, we're not seeing drastic results. After building up for three or four weeks, we have a cumulative level of deficiency that's actually impacted plant health at this point. So I think it's important to establish whether we're dealing with something like slowly drifting ph over time deficiencies.
Seth [00:26:02]:
Obviously, when that happens, you see a lot of light yellowing or when we're pushing 1000 plus ppfd, provided we have enough vpD, dehumidification capacity and CO2, a lot of these plants can take up a lot more salt than you might have ever seen growing them under less intense conditions before. And we're seeing that stress from the light, that's kind of a result from low EC. Usually one of the best, I don't say the best things to do, the easiest things to do is to turn down that light intensity and, you know, kind of take that plant out of overdrive quite as hard. And that's great for plant health. Unfortunately, the more micro moles of light we can pump into that plant over anywhere from, you know, 56 to 70 days, whatever your flower cycle is, the more potential yield we're going to be able to pull out of that crop. And so, reactionarily, if I'm trying to save my plants, I'll turn down the lights a little bit, really try to get that EC and ph data and go through it. And I know that turning down the lights, I'm going to decrease the amount of production that plants trying to put out, take out quite the demand for all that fertilizer and CO2 and, you know, let it relax a little bit. But understand that that is going to cost me at the end of the day.
Seth [00:27:16]:
Not yet determined, but eventually over time, with averages, you could see what the cost is in lowering that light intensity for a period of time.
Kaisha [00:27:26]:
Amazing. So to our grummy Seth, you're on with us. Anything else you want to add? Take that as we're good to go. We appreciate you asking the question today. If you have any follow up, drop it in the chat. Yeah. Amazing. All right.
Kaisha [00:27:41]:
And another quick follow up on YouTube from stardyes who asked a question about nighttime temps dealing with high ceilings. They wrote, thank you, Seth, working with TJ Herman from Revolution, Missouri. Know you met him. So little shout out. Love it. And to our grow me, Seth. You're so welcome. Thank you.
Kaisha [00:27:58]:
Glad you're here. All right, we're going to keep it moving. We got this question from our good friend Iron armor. Dropped it on YouTube. They wrote, in a situation where I need to conserve electricity, can I keep my mother plants in bed with a twelve hour light cycle by oscillating my light cycle to four on and four off? I want to get your thoughts on that. Or will that cause negative effects, do you think?
Seth [00:28:23]:
You know, personally, I have not experimented with that, but I wouldn't necessarily count on it producing positive results. It's certainly not ideal. You definitely want to keep your moms on an 18 hours light cycle whenever possible. And I mean, your bedroom should be on that light cycle. But that's. I would be interested to know the situation where you do have to go 4 hours at a chunk. That being said, it is something intermittent darkness interruption, something that's used in other crops to induce flowering or reduce it depending on the crop. But in cannabis, usually we see deviation from that.
Seth [00:29:00]:
Twelve or 18 hours life cycle lead to varying stages of pre flowering occurring in the mothers. So it's, it's going to be highly tough to predict and probably strain dependent, where much like vegging under 24 hours of light, you might see some strains that do just fine with it and then other ones that seem to do odd things. And if you do get a mom that's starting to pre flower, you're going to have a very interesting time flowering out those cuts that already started to pre flower and in a very different hormonal state than they need to be in when they go into stretch. So I would try it out, but I wouldn't want to transition my whole mom crop to that immediately.
Kaisha [00:29:38]:
All right, you heard it, iron armor, let us know how it works for you. Thank you for your question. It's always good to hear from you. Okay, we got this right in. Somebody wrote, hey, can you guys talk about the difference between field capacity and fully saturated? If my field capacity on the bag says 62 volumetric water content, but when I saturate the pot, my sensor reads 80% during bulk. Should I wait for the substrate to come down from 80% to 60% and then start doing 2% shots every hour, or should I be keeping the substrate closer to 80%? I'm kind of confused and don't want to over water. That's a real journey.
Seth [00:30:17]:
Yeah, yeah, absolutely. You know, when we're looking at field capacity and saturation, those are 100%. Saturation is always equal to field capacity. And that's the point that the media has completely absorbed all the water that it can and any more that you is going to run off. Right, but volumetric water content and field capacity are two different scales. So field capacity is going to be directly applicable to the only media you're testing. Volumetric water content at field capacity also will be directly related to that. However, because we're using a known volume, we can actually compare that to other samples.
Seth [00:30:54]:
So 100% is 100% is 100% on every single plant in the room at runoff. Right. But when we look at field capacity and volumetric water content, now we can start looking at different pots and saying, hey, especially if we're using cocoa, for instance, some of these pots are achieving field capacity at 48% volumetric water content, and some of them are achieving field capacity at 55% volumetric water content. And anytime we're looking at Coco, it's really important to remember. You know, it's a cheap byproduct of another industry that's been repurposed, luckily to be brought to us growers at a pretty reasonable price, and it's actually a good substrate. That being said, we do see a little bit of variability. And, you know, what I always like to tell people is like, hey, you're paying anywhere from one to $3 a pot. If you want to pay ten to $20 a pot, then we might get to a manufacturing level where we could say, this is all exactly the same.
Seth [00:31:43]:
But the reality is we do have a little bit of a range we're working with. So what we want to start looking at is appropriate dry down, dry back numbers that indicate good transpiration in the plants that's healthy, and then also enough pore space opening in the root zone that we're not overwatering and promoting anaerobic conditions and poor root growth in the media. And typically, we're looking for, you know, at least a 10% dryback every single day. And when we're talking about, you know, the beginning of veg or the flower cycle, we're rooting a plant in. My general approach is to go fairly light with two to three evenly spaced shots per day while rooting in and not bringing that plant or pot back up to field capacity until we see at least a 15% to 25% dry back across the room. And what that's doing is telling us, hey, those roots, especially if you have a sensor installed, all at the correct height down towards the bottom of the pot at one and a quarter or two inches, once we see that part of the pot drying out, that's a good sign that we're actually getting root penetration down that deep and we're opening up that pore space. And now we know if we put, you know, another 20% of water content back onto that pot, we're actually going to be pushing, pushing oxygen down, pulling it in as well, and actually refreshing that root zone. Whereas if we just keep it up close to, you know, if you're in Rockwool or even some cocoa hitting up close to 80% and you keep it up that high the whole time, that's what's going to make the plant stay, or put the plant in a state where we'd.
Seth [00:33:10]:
We'd call it over watered, it's anaerobic, and we're not getting good root growth. So the best approach, right, you know, is to just wait until you get that dry back. Small, one percentage less shots, two to three times throughout the day and really watch to make sure you're getting that dry back. And, you know, if it's been ten days in a one gallon or, like, let's say even longer in a two gallon, we're not seeing any dryback. That's when we start to look at environmental conditions or possibly contamination in the root zone. Do we have fusarium pythium or some other form of root rot that's preventing root growth in these pots?
Kaisha [00:33:48]:
Love that question. Good luck out there, whoever dropped it. And then we also check out our education guides. We have a great one on field capacity. I think we have one on water content. I can't remember, but field capacity for sure.
Seth [00:33:58]:
Yeah. And one thing I want to point out is, you know, there's a lot of talk around both because if you don't have something like a direct substrate moisture content sensor that's accurate, part of what you're doing on your hand feel gauge is going, hey, I've achieved field capacity. What does that feel like? Right. So it's not that, you know, when we're talking about saturation levels that it's irrelevant. It's just really important when you're looking at different information, you're finding out there to determine whether they're talking about saturation or volumetric water content. When you're looking at what. What anyone said they did for a dry bag, because they're, you know, both are expressed in percentages. It's really easy to conflate the two.
Seth [00:34:40]:
And as growers, you know, some of us are way more social, depending on where we're at. And then some don't get the opportunity to talk to as many other facilities. So maybe the group that you're talking to is almost always talking about saturation, depending on the tools they're using. And you might talk to someone who has only used volumetric water content. And I. Unless that question gets asked, a percentage is a percentage if you're just talking numbers back and forth. So you don't want to conflate those two.
Kaisha [00:35:11]:
Excellent clarification. Thank you, Seth. Thank you for that question. Let me just take a moment. We did a little YouTube poll here. So the question was, where are you watching from today? East coast, west Coast or central? Us. We got 12% checking us out on the east coast, 25% checking us out in the west coast, and 62% check. I'm sorry, 25% in central, 62% checking us out on the west coast.
Kaisha [00:35:36]:
Cool. West coast. That's where I'm at. We appreciate all of you for checking us out and I'm going to keep it moving. We got a great live question here from high cloud society. They're doing flood and drain. What would be a good EC range to increase to and build up the EC in late flower and how long do I leave them flooded?
Seth [00:35:59]:
The flood and drain is going to be a little tough because the longer you leave them leave them flooded, the uh, closer to that nutrient. You know, your just your general flood solution EC, you're going to be. One unfortunate thing about the flood and drain system is it is somewhat difficult to build EC in the root zone because the, like I said, the longer we flood, the better, the better absorption you're getting, but also the less ability you have to build up EC in the root zone. So if you are running flood and drain, probably part of what, what it comes down to is how high you feeling to push the feed EC and how intensive lights are you going to run and how intensive an environment are you going to run. I've certainly seen some success with flood and drain setups in greenhouses without CO2, for instance, where there's really no reason to push that light intensity above six to 700 because we don't have the CO2 to support it. So not as much of an issue there on the EC as far as values go. Typically if we're hitting 600 to 1000 ppfd, we want to see about a three to a seven EC in the root zone, in generative, even up to a four. I like to see a four slightly above to maintain good plant nutrition.
Seth [00:37:07]:
But again, if the lights aren't being pushed as hard, we don't necessarily need that level of fertilizer in the root zone. That being said, we'll typically see a little bit less of a swing on the ripe or bulking period. So we'll go into bulking, bring that up to field capacity. We're watering later in the day, so we'll see a similar baseline you see in that three to four range, in your case most likely, and then drying back to, you know, maybe a six or a seven, but probably not quite as much because we're not drying back quite as far in bulking as we're putting on water later into the afternoon and then in ripening. We want to see usually about a three to a six EC range, making sure that we're not spiking it too high with those generative drybacks and trying to keep it in a fairly narrow range and slowly bring it down, especially if we're looking at feeding a solution where we haven't been able to remove very much nitrate, so achievable results. I think it might just be a little harder to get that EC up above a 3.03.5 without spending a significant amount of money on fertilizer.
Kaisha [00:38:12]:
Okay, you heard it. High cloud society. Keep us posted. All right, we got this question. It's been a few weeks. We can't always get to them, but we hold onto them, y'all. So we appreciate you submitting them. This came from Jeffrey Jordan.
Kaisha [00:38:25]:
Dropped it on Instagram. They wrote, I was wondering if you could give some tips on best practices to keep root temperatures down. I'm at a facility where we use drip feed and we're dealing with pretty high root temps consistently over 75 degrees. Summer isn't helping, but even in the winter, with a feed temp of low or mid sixties, it is hard to keep root temps down. We run led lights with 82 to 78 degree rooms for most of the growth cycle, and we use rockwool unislabs. Is this just what is going to happen in a higher temp grow? I know water temp and airflow help a lot, but I was wondering if you had any other tricks. Also, if you're using a hypochlorous acid product, would you increase the dosage if the temperatures are rising? Bus pod out there. Thanks, guys.
Kaisha [00:39:09]:
Such a good question. We are dealing with some hot summers. So what do you think, Seth?
Seth [00:39:14]:
I mean, you know, probably the best practices you can really employ for that are good room control, good airflow. If you can have a white wrap on your slab, that's better. And if you can have white tables, you know, anything to reflect and not absorb the light as much. But part of the reality is that, you know, when we have this big wet slab, cocoa pot, anything, we have a certain mass of water in there that's there 24/7 in the room. So that's always going to be close to the ambient temperature of the room. And then we go to irrigate. Even if we're putting on, let's say, water that's been chilled all the way down to 45 degrees. And I've definitely had this discussion several times.
Seth [00:39:50]:
We're not putting a volume on at each irrigation. That's enough to really affect that root temperature as much as you might want. So the question becomes, are these higher root temperature, root zone temperatures actually affecting the plants in a negative way? And typically the way they would affect something negative is over saturation, overwatering, where we don't have enough oxygen being able to be pulled into that root zone, don't have good rooting. And at that point, now we're starting to grow anaerobic bacteria because we don't have an oxygenized root zone. So in those high temperature situations, I mean, number one, you have to look at, hey, we're getting up close to 80 degrees. This mass of water is existing in that all the time. It's going to get close to 80 degrees. And, you know, if we're talking about Rockwell slabs, for instance, if you're hitting 65% to 70% and drying back to 30% and you're putting water mass on at a rate of, you know, up to five or 6% at a time and then spacing that out 15 or 20 minutes, it's just not going to have that much of effect on root zone temperature.
Seth [00:40:54]:
But if we can ensure that we have plants well rooted in, we're actually getting enough dry back every day in the ten to 30% range, then we know we're opening up that pore space and we can shoot fresh water and oxygen into that root zone to keep, you know, the root zone free from anaerobic bacteria. As far as hypochlorous acid goes, great practice. There's not really a reason to run a higher volume of it, unless you are seeing a lot of things like root rot, which if you cut open that slab, look along the bottom of it, and you're seeing dead brown roots, lesions on the base of the plant, that might be an indication that it's a good idea to start using that for basic sanitation. But then the next step is identifying. Is that contamination coming in from the table? Is it from the bedroom? Is it from the mom? Because once we have a plant that's already infected with fusarium or pythium, for instance, that we can't just go give it a penicillin shot and clear that up. We can try to sanitize it, but that's just like you dumping hydrogen peroxide on your cut. That doesn't necessarily heal it. And plants don't have an immune system that can necessarily actively fight a pathogen in the same way that we do.
Seth [00:42:02]:
So that's kind of the line there is determining, hey, do we actually have a problem that's resulting from this? And then what are the levers I can pull? And typically, it is trying to push that dry back, targeting those smaller shots and focusing on oxygenation rather than root zone, followed by cleanliness. And one, unfortunately, thing, fortunate thing about things like fusarium and pythium is much like we always talk about aspergillus and metritis on this. They're fairly ubiquitous to our environment. You can pick them up in the parking lot, walking across your front lawn pretty much anywhere. And that's another reason that for years and years and years, if you're not already doing it, I've always done it. Have separate shoes for work. You have a pair of shoes that you sanitize, you're always walking over. Bleach pads clean out at the end of the day.
Seth [00:42:52]:
And they also don't leave the facility. So that you're just never taking them out into an area where you might encounter some of these pathogens and really reinforcing some of those really simple biosecurity protocols. The same as if, hey, if you go into a sick room of plants, it's never ever a good idea to go back in the bedroom, even if you don't know why that room is sick. And if everyone's on that page, you can at least effectively track where some of these points of infection may be coming from and start to do something about it. Because if you can't find the source of where your infection is coming from or problem, then all you're doing is, you know, basically reacting and trying to clean it up on the back end. But it's going to keep coming in and be a constant problem.
Kaisha [00:43:37]:
Wonderful. Thank you, Seth. Jeffrey, that was a great question and thank you for your patience. Sometimes it takes us a little while to get to the questions, but when it's good, we got to ask it. So we appreciate you sharing your journey with us and keep us posted. Want to give a quick shout out. We're global. We got some viewers here in the UK, Brazil, we got Puerto Rico represented.
Kaisha [00:43:56]:
So welcome gromy. So happy to have you on the pod. Just a few minutes left, still in the show, so if you have any questions and you want Seth to ask them live, now's the time to drop them in the chat. We got this one on YouTube from Mister Grinch. They wrote, can you talk about reservoir aeration, please? Is it even needed? How long can a res sit before needing aeration? What is your preferred way to aerate? Etcetera? Thanks. Love the show. Thanks, mister Grinch. Reading says aeration.
Seth [00:44:25]:
I mean, aeration is very important and a lot of it too is dependent on what kind of temperatures you can keep your water at. So we can keep that water well under 70, 70 degrees in that like 62 to 66 range. We typically have pretty good dissolved oxygen retention. That being said, the longer that water sits, the more you get that oxygen to gas off. So as a small precaution, I think air stones are probably one of the best ways to go recirculating pumps with a certain fall distance so you're getting enough splashing, and oxygen injection is also a way to go. However, those can be a little less reliable and more problematic than just running an air pump. If you're not running one, I would strongly encourage you to do so. Personally, I can easily have a tank sit for three to four days, no problem with an air stone in it, and not, you know, notice any bacterial buildup, provided I can keep that temperature under 70 degrees in the tank.
Seth [00:45:18]:
So kind of a two pronged approach. And if you're starting to go above that 70 degrees, we see the water's ability to hold dissolved oxygen decrease dramatically. And that's why you see, you know, different species of fish in different water temperature zones. Because some fish need more oxygen and it equates to colder water, some fish can tolerate lower oxygen levels and warmer water. So you need to identify what your situation is and what's actually going to be more achievable. Because sometimes, if I'm going to install an inline chiller and an aeration system, maybe I should look at insulating my irrigation room, where that mass of water sits, and making sure that that's always cold enough. If I've got incoming water from my city or whatever local municipal source that I can get it coming in at 75 to 80 degrees, I might be forced to be spending more on inline chillers and insulated tanks and whatever's necessary to get that water temp down below 70 degrees. And if I can't get it down, how do I oxygenate it? But that's always something to balance, you know, if the water temps high, we're even with aeration at 75 degrees, 80 degrees, that water just won't hold nearly enough oxygen.
Seth [00:46:28]:
Not as much as we want as it would at 65 degrees.
Kaisha [00:46:35]:
You're amazing. That's awesome, Seth. You're a real one, Mister Grinch. Thank you so much for your question. I was dying to say that. All right, we got this question. Someone dropped this in the bank here. They want to know, how would you go about measuring leaf temps in a large, perpetual harvest greenhouse with HPS supplemental lighting that can range from one to 3ft from the canopy to achieve a relatively accurate average of temperature across the room, how many measurements would you take? How deep into the canopy would the measurements be? So, looking for a little overview of checking leaf tents in a perpetual harvest?
Seth [00:47:13]:
Yes. I mean, the easiest way to approach it's with a thermal heat gun or a flir gun, so you can go color code and get a really easy average of what you're seeing. And basically, it's kind of about how many data points can you collect to achieve a certain amount of statistical significance. So if we want to map out the whole canopy, we're taking several, several samples, I mean, hundreds and hundreds from. From around the room at various heights, from the top of the canopy to the bottom, recording at what level we're seeing those different temperatures and trying to map out what that heat saturation and depth looks like. That's kind of the two options. It's either high tech quick scan or painfully manual with many, many, many points of data. As much as you can get until you start to see consistency.
Seth [00:47:58]:
That, hey, I am measuring at 36 inches from the light, and this is the temperature that I'm confident we're seeing across various growth or across various phases of growth. And that's going to differ a little bit as your plan stretch and get taller closer to the lights, they will get a little bit warmer. Yeah. And as far as, you know, specifically in the perpetual setting, that just means you're going to have to be more meticulous with your notes and take more and more zone specific readings and map the room probably even more so that hopefully, over time, as you develop this heat map of the room, you can start to optimize and say, hey, I'm getting more favorable conditions for early flower on one side of the room, or how can we manipulate this room even though we have one big space, to have microclimates that actually work with us to help achieve that or establish that, hey, with the shape of our room and our equipment, the best we can do is find a happy medium and leave it there. But if you don't have all these different points, it's really hard to establish how, how big and what kind of microclimates you might be dealing with. And sometimes when we're looking at, you know, even HPS or Led, the difference between the two leaf surface tents, things like airflow, can be an incredibly huge factor. So you might find that certain parts of the room, we're seeing a, you know, three degree positive differential on the leaf temp versus ambient air temp when in the same room in the same lights, 10ft away, we have a little bit different fan configuration. There's a higher wind speed over there, and we're seeing those leaf temps right at ambient room temp.
Seth [00:49:28]:
So that's another thing to look out for. You know, it's not just light height that's going to dial that for you. It's also what airflow is doing in your room and what, you know, even fan placement can relate to how hot is that air that's actually blowing across the canopy. We have a lot of different energy inputs going into this room, and if you don't map them, you can definitely chase your tail a long time trying to figure out why this corner of the room is condensating. And then the other corner, we've got, you know, plants that are starting to have some leaf crisp going on because it's too dry and it's hard to see airflow. So the best you can do is really go start mapping that. And I focus on that, you know, few millimeters around the plant surface, because everything we do in this controlled environment really caters to just a tiny, tiny amount of space on the surface of these plants.
Kaisha [00:50:16]:
Shout out to our grow mates and the perpetual harvests out there, that's a, that's a whole different beast. Good luck out there. And we love these questions. We're going to wrap up the show a little bit early, but before we do, I do want to say, if you love Arroyo office hours, we would love for you to nominate us for the MJ's content creator of the year. They're accepting nominations until August 18. That is Sunday. So please do consider nominating us. We certainly appreciate the love.
Kaisha [00:50:43]:
All right. With that said, Seth, thank you for holding it down solo today. We appreciate you.
Seth [00:50:47]:
Yeah, thanks, Aisha.
Kaisha [00:50:48]:
Awesome. And then producer Chris, thank you. Can't do it without you. Thank you both for another great session. And thank you all for joining us for this week's Arroyo office hours. To learn more about Arroyo, book a demo at Arroyo IO and our team will 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 Arroyo app. Email us at salesroya IO.
Kaisha [00:51:11]:
Send us a DM. We're on Instagram, Facebook, LinkedIn, and we definitely want to hear from you. If you're a fan of the pod, please leave us a review on Spotify, Apple Music, YouTube, wherever you listen to your podcast, we appreciate your feedback. And be sure to subscribe to our YouTube so you never miss an episode. Thanks, y'all, and we'll see you at episode 113. Bye.