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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, Gromies? Welcome to Aroya office hours, your source for free cannabis cultivation education. I'm your moderator, Kaisha. You are on episode 96. 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 will cover it during the show. Seth, how you doing over there?
Seth [00:00:22]:
Not too bad. Can't complain.
Kaisha [00:00:24]:
Good. Yeah. Holding it down in studio. We got Jason at Hall of Flowers Ventura. If you all are out there, keep an eye out for him. But let's just go ahead and get started with some questions. This one came in from our good friend Indiva. They dropped the question, why do you call drybacks a percent versus points? As it's very confusing and doesn't make much sense.
Kaisha [00:00:45]:
For example, 10% dryback of 60% is 54%, but you say it's 50%, so wouldn't points make more sense? A ten point dry back from 60 equals 50. What do you think, gromies?
Seth [00:01:01]:
Basically, we say percentages to keep it in the same scale because we're always talking about VWC and percentage. So how I usually approach this with people is instead of making that calculation of a percent of a percent, I'm always going to tell you on the same scale that we're measuring in. So in the case of, let's say you had a 65% VWC field capacity, a 30% dryback would be drying back to 35%. And the reason we talk about that that way is just to keep it simple. If it helps for you to use the term points instead of percentage when talking about that, that's absolutely fine. I know I've definitely encountered plenty of people that just that little word change really helps with the concept grasp. But that's what we're talking about. Always just VWC.
Seth [00:01:44]:
Keep it simple. Keep it easy.
Kaisha [00:01:46]:
That's right. Keep it simple. Keep it easy. But love that question. It just goes to show a lot of these interchangeable terms can be a little confusing, but love that question. Thank you for submitting it.
Seth [00:01:55]:
Yeah, I'm actually glad that was brought up, because I think that's something that there's a lot of talk about crop steering and drybacks in general and a lot of talk about what's going on with water content. And historically, a lot of us were talking about saturation for years and years and years and years, considering field capacity, 100% of our saturation. And if you're used to talking about saturation, it's really easy to not be speaking the same language as someone else who's talking about VWC in the same conversation. So I'm actually really glad that was brought up. I get asked that a lot on a day to day basis, and it is confusing. There's a lot of information out there, and there are people who speak very confidently and have written a lot about saturation, and that information is relevant if you're working with that scale. So, yeah, thanks for bringing that up.
Kaisha [00:02:45]:
Thank you for that. Great answer, Seth. All right, on the topic of field capacity, we got this question in from Sam. They wrote, have you guys got any idea why your field capacity could increase? I'm using can of Coco, and my field capacity was at about 40, right through veg, up until the second week of flower. It's now gradually gone up to 50. What do you think?
Seth [00:03:07]:
There's a few factors there. So, number one, when we're looking at plant roots, for instance, they are made up of mostly water. So as those roots grow around your probe, they can actually cause your water content to increase a little bit. Sometimes, other times. Another thing we're seeing is that depending on how you prepared that media, how your initial soak went, if you didn't achieve your full field capacity with your initial hydration, your plant can still grow inside of that media. And during veg, depending on how long your veg is, too, especially we're not necessarily putting on as much water at once or as big of a series. We're maintaining. And once you go into flower, you might be actually applying a lot bigger irrigations that are pushing that field capacity up.
Seth [00:03:48]:
Another thing to look at, too, is how much water you're putting on in veg. I myself have definitely practiced and seen many situations where it's a set it and forget it veg schedule that gives it, let's say, six to eight shots a day. In that situation, I've definitely found times where I'm pushing too much water and I'm actually getting channeling. It's just not necessarily affecting my veg performance because I'm not trying to build ec yet, especially if I'm in a situation where I'm vegging in a smaller container. We'll see that happen quite often. So a few different avenues to look down, for sure. But what you're seeing is completely common. And also, if on the other end of your flowering cycle, the last week or two, you start to see that field capacity diminish, where you're not getting to quite as high of a content when you get runoff, oftentimes that's a sign of an extremely root bound plant at that point where we've just crushed all the pore space, or a huge portion of the pore space out of the block, filling it with roots.
Kaisha [00:04:45]:
Awesome. Thank you for that advice. And I just dropped in the chat. We have an education guide on field capacity. It's a good one. Check it out. I wrote it. I'm really proud of it.
Kaisha [00:04:54]:
Okay, we got this question in from Tim at Bluminati Farm. Submitted this recently. In an earlier episode, I heard you mentioned, Seth, that I like to deleaf in a second time, if I can, before the end of stretch. And I've always heard that when you deleaf during stretch, that it releases some kind of hormone that makes the plant stretch even more. So did I hear you wrong or did I hear wrong? As far as the triggering of stretch, when deleafing during stretch, can you explain? Thanks.
Seth [00:05:24]:
Yeah. So there's a few different ways to go about deleafing. Obviously, a lot of people have different strategies. The one I typically subscribe to, especially if we're going for mostly quality flour, if you're vertically integrated and can produce everything from top quality flour all the way down to joints and extracts, there's a little bit different approach where we're not necessarily lollipopping it up in the beginning, but part of the reason for that timing, for that default, there's a few, and there's a few different techniques to look for when you're doing it too. Number one, when you do start popping leaves off of the plant, you're creating an open wound, which will stimulate oxygen production in different parts of the plant mainly. Well, not different. Specifically, your apical Marist ends the tips of your branches. So when I pop that leaf off the plant, sending a signal that it needs oxygen to basically form a callus or a scar over the wound.
Seth [00:06:13]:
Let's say if we're thinking of animals and not plants, the problem is the same compound that helps form that callus tissue is also responsible for both rooting and stretching in the plant. So because that hormone is produced at the very distal ends of all of our branches, the tips, it's got to travel down through that branch, all the way down to that wound site to induce that callus production. So in effect, it's exposing that whole branch to oxen and producing stretch. Now, there's a few different ways to combat that. Number one is really trying to time that deleaf for the end of stretch. So we're getting maximum growth with those leaves while we can. Number two is to look at your deleafing strategy and how you're actually doing it. If you grab a leaf and rip it downward immediately and you're getting stringers that come off and go down below it, you're making a bigger wound that's going to need to be healed.
Seth [00:07:03]:
If you can take snips, leave just a quarter to a half inch of that pettyle there. Or just for speed, I just use my thumbnail personally, pinch it like that, move my thumb over. But leaving that little bit of pettyle allows us to work with the plant's natural response to being able to drop leaves. So cutting the pedial will let the plant actually develop that abscision zone is what it's called. And basically the plants can put a lot of phenolic compounds into xylem and floam that connect to that base of the pettyol and close that up without actually producing an oxen response. So some plants will respond more vigorously with a bigger oxen push and more stretch. However, some won't. So again, it's always a sliding rule here.
Seth [00:07:46]:
My personal theory with that is the more I can do to work with the plant and not against it, which any kind of wound response is going to be working against the plant. That's the direction I want to go. And these days we have a lot of commercial producers that are defoliating once in the entire run. Like I said, if you're vertically integrated, you might not defoliate except for later, maybe day 42 or something to go get some of those fan leaves that are dying off down deep in the canopy just for hygiene purposes. But anytime we're popping leaves, we're always looking for a balance between getting light penetration into the canopy while also maintaining enough foliage to actually photosynthesize and produce enough sugar to grow those buds.
Kaisha [00:08:33]:
All about finding balance. Awesome. Okay, thank you for that overview. All right, we're getting in some live questions on YouTube. Danny dropped one. They write, Floraflex says in grow guide if ph of runoff is rising by 0.5 or more to raise EC. But isn't that the opposite of what Seth teaches? Sorry to hit ph again. It's all good.
Kaisha [00:08:57]:
PH is a pretty thorough topic. We appreciate the question. Danny, what do you think, Seth?
Seth [00:09:02]:
Yeah, anytime our pH is drifting out of range, the odd solution is that we're probably going to raise the feed EC and try to reset that balance. And the reason for that is raising that EC gives us more positive and negative ions. We've got more to push in and push back out so, although it seems counterintuitive, anytime we're trying to stretch that, we need to introduce more ions, not fewer, in order to reset that balance. So if you can think of it as like, hey, I'm pushing that back towards a baseline by introducing a big enough volume of higher EC water to push out either the positive or negative ions. I want to adjust that.
Kaisha [00:09:41]:
All right, Danny, there you have it. Keep us posted. Give us some follow up as you continue on with your ph journey. Ok, this question came in from our good friend Iron armor. What's up, Iron armor? Over on YouTube they write, what is the main purpose for doing an open pollination? Synthetic breeding. And can you give a quick overview on it?
Seth [00:10:03]:
Yeah, so, I mean, the main reason for that is when we go with an f one cross, let's say two parental lines, and it's that first initial cross, we're going to see a high degree of uniformity in those f one seeds. So when I plant all those out, yeah, I'm going to have some phenotypic differences, but overall we're going to see a similar smell, fairly similar bud structure and similar plant structure. And like I said, there's always going to be what we like to call winners. Out of those, you pop 20 seeds and some are better. But in order to see the full expression that's available out of that cross, the total genetic variability, we need to basically have an inbred line and take that out to f four, five, six and beyond to see what's in there. Because once we start looking at a cross square and we start figuring out all the possible combinations, there are certain combinations of recessive genes that we can't get without taking that out for several generations. And if you're selecting each generation in that process, you're not necessarily going to get an unbiased view of what kind of variation you might be able to see. So if I'm looking for, let's say just cross two plants and one of the things I'm looking for is mold resistance in this one plant.
Seth [00:11:13]:
And I want the trying to get mold resistance out of one plant and I'm trying to get the structure and smell of another, I'm going to cross those two. And in that first generation I might not see anything like what I want to get out of it. But if I go out to f two, f three, f four, with synthetic pollination open like that, I'm not biasing it towards anything. I'm going to see if, like, hey, throughout these two, three, four or 5000 plants, there might be that one special one that has that recessive combination that I'm looking for. And sometimes I need to get that variability in order to go back and start my back crossing process and bringing in more and more of those recessive genes. So basically, it's a numbers game, and that's one of the more efficient ways to get the most possible crosses you can get out of the smallest possible area and maximize your time. Because at the end of the day, too, if what we're looking for, if we do the math, and this trade is going to take one in 10,000, that's the recombination rate we're seeing. I need to maximize the number of potential crosses within that line to pull that trait out, because I'm not necessarily going to be able to blow up each generation to 10,000 seeds right off the bat, and I might not be able to plant out a whole crop to just search for this one.
Seth [00:12:28]:
So it's a combination. And right now, we don't see that as much in cannabis breeding, just due to space limitations. But over time, I think we'll see more and more of it. But who knows? That's my opinion coming from traditional plant breeding. One thing we're seeing in the cannabis market very heavily is high strain rotation within facilities and markets. So that's another thing that's a challenge, right, for some of these breeders is how do I go about putting out the next big thing, the next new thing, the next very different thing, when it takes me several generations working with one line to get a result that I want? And how do I balance that production cycle on new strains? Like I said, if it takes me six years to get my perfect strain and then I put it to market and it's only popular for six months, that's kind of a limitation. So I think for a while we're going to see quite a bit of strain rotation, and it's going to take some time for the cannabis breeding industry to catch up with the advantage that traditional Ag has had in that space. And at the end of the day, it's all market driven.
Seth [00:13:34]:
So if the public settles into preference for certain strains for longer periods of time, which could happen, we don't know, then that's going to dictate a little bit better breeding model. And then also it's what the growers demand. Right? So when we look at, again, traditional egg, we look at different cultivars and varieties of plants. If you're growing them in certain areas, you might want a certain variety that also has a particular type of disease resistance that's prevalent in that area. So for cannabis growers like, hey, we all want a fuserium resistant plant, a botritis resistant plant, a powdery, mildew resistant plant, and that just takes enough variation. A lot of those traits are recessive or double recessive traits that are difficult to isolate into one line. And we're just in the infancy of gathering all this. There's companies like Phylus out there that have a genetic library and have been looking at different markers, and there are various gene sequencing labs out there doing this.
Seth [00:14:28]:
I mean, even Dewey scientific here in Pullman is looking at disease resistance in different strains, but they don't have big university support for this. There's not nearly as much money flowing into these projects as there are in other parts of eggs. So we're just not quite seeing those really advanced results quite yet. They're out there. But in order to get enough of these really good traits into all these lines that growers actually want to produce, it's just going to take quite a few more years.
Kaisha [00:15:00]:
Yeah, the genetics conversation is just always so fascinating. I'm personally a big fan of the diversity of the plant.
Seth [00:15:07]:
Oh, yeah, well, it's expensive to do gene sequencing and do all these breeding projects. You've got to find a way to economize it. And there's not much money going into cannabis research right now, and the licensing is very difficult. I've got to put up a facility and have the research capital to run it. If I get a research license, I can't sell my product. And if I'm in a commercial license, I can't have different packaging for absolutely one of the 2000 different phenos. We ran through that run. So there's some strategic limitations there.
Kaisha [00:15:42]:
Strategic limitations. But I'm only one consumer out there. I like to have all kinds of options available to me. So we appreciate all your efforts. Growers and breeders.
Seth [00:15:52]:
That's one thing that's cool. Even, like in the world of apples and stuff, a lot of cool, not new. Old cultivars that are being brought back into breeding projects are coming from stuff that was not planted from current seed stock. It's old, or it was found growing wild in an orchard or something. Same thing as cannabis growers, just finding a seed in a bag and popping it, you never know what you're going to come across. And the variation is amazing. Just like you said, kaisha, that's what I think keeps a lot of us really enjoying this plant. There's so much variety, so much variety.
Kaisha [00:16:28]:
I love you forever. Blue dream. Anyway, yes, thank you so much for that question. Our friend carpet dripam is on the hangout right now. Dropped a question. Could I use a terrace twelve sensor in a similar way as a terrace one, like stab it and leave it and just reconnect for a more accurate and consistent read? What do you think?
Seth [00:16:49]:
I mean, absolutely. If you've got, like, the solace unit, that's actually a popular thing I've seen where people will unplug it so they're not going to accidentally get their bluetooth dongle wet, but they'll just go in, plug it in, take a reading, then leave it in situ. That way it allows the roots to grow in and you're getting a true in situ measurement. The solas individual spot check measurements are great, but if you don't have a big garden, if I only have twelve plants, that's going to lead to me stabbing those plants a lot and kind of stirring up the media and not necessarily getting the most accurate results and also possibly opening up channels for that water to flow out where I don't want it to. So if you have a small plant count and you're really trying to dial it, leaving that sensor in situ is probably your best bet at getting the most accurate readings, especially if you want to take them day after day after day on the same plant.
Kaisha [00:17:41]:
Fantastic. Harpe, good luck on your journey. Keep us posted. All right. And thank you for joining the hangout today. Nice to meet you. All right, we got this question in from YouTube. I'm not going to pronounce the name right, so I'll skip it.
Kaisha [00:17:53]:
But they write, supposing I have the proper environment, PPFD, CO2, et cetera. How long would you recommend vegging five gallon pots? I was thinking around one month. And how many per light to pull? Three pounds per light. Got any advice for this person?
Seth [00:18:14]:
I mean, for starters, I would probably save your back and veg in a smaller pot. That's going to make vegging a lot quicker and easier. So if I was going to do a five gallon pot, I'd probably be looking at a three week veg inside of a 0.3 gallon to one gallon coco container. Maybe even up to a month, we're going to be flipping a pretty big plant. And I guess my biggest question is, if I could ask you a question be why do you feel like you need to grow in such a big pot? Because there's different limitations. The most time efficient systems are going to occur in smaller pots. If you're in a plant count situation where you're only allowed to have, let's say, six plants, then, yeah, we do want to get a lot bigger plant. As far as, like I said, veg time, three weeks to a month.
Seth [00:18:56]:
If you're vegging in a smaller pot in that five gallon, you might be looking at more like a five to six week veg. To get a three foot tall plant. To flip that, you can expect to hit that seven or 8ft and you can really train it out. There you go. I would highly recommend vegging in an intermediate container, though, from clone. In the five gallon, you're going to have a lot faster rooting in. And like I said, your back is going to feel better because you don't have to move the five gallon pot from the veg to the flower room. If you're vegging in place, all the more power to you go right into the five gallon.
Seth [00:19:29]:
But it's going to be a lot more challenging and take much, much longer to hit that plant size pot.
Kaisha [00:19:35]:
Size really does matter and your back does too. So, yes, all right, great advice. All right, we got another question here. In the chat about genetics, do you have any insight on growing triploid cannabis plants? Seems pretty neat. What are triploid cannabis plants? Seth?
Seth [00:19:53]:
So, normally you have diploid cannabis plants, two sets of chromosomes. Triploid would have a third copy of all the chromosomes of the plant. I've never personally quested to grow triploid cannabis plants. I've seen them pop up out there, not in the wild, but in production facilities as mutations. I think it would be a fun adventure. However, we can have triploid tetraploid like. Polyploid plants in general have different expressions, like most of our current wheat, for instance, has six sets of chromosomes. A lot of different crops are tetraploid crops.
Seth [00:20:30]:
However, in cannabis, we haven't necessarily seen a correlation between more sets of chromosomes and a higher yield, which is part of why we want those in, say, wheat. Instead of a two row wheat, you have a six row wheat, three times as much seed on the same stock. In cannabis, we're not going for seed, and so far, I don't think there's been a lot of need to research that. If you have access to some, you can confirm it, either genetic testing or get a really nice microscope and look in there at the right time to try to see how many sets of chromosomes you got floating around. Play with it. I would please send me pictures if you get some really funky looking nugs that are huge. But usually what I've seen is some odd bud formation and not necessarily an increase in quality or quantity. However, like I said, if it looks cool to you and you just like that picture.
Seth [00:21:26]:
Personally, I love every once in a while growing, like, some old tie strains and stuff that don't produce big nugs, but they have really big bracks and just a different looking flower. And I think that's more the difference we'd see there. And that being said, beauty is in the eye of the beholder. At that point, we're hitting a boutique market where if I can find. I love going out and seeing, like, a chocolate tie somewhere that's just old school, has huge bracks, not very big nugs, but it's a very distinctive look. And that's probably what we'd be looking at with AAA genetics.
Kaisha [00:21:58]:
I heard about chocolate tie. I've never actually tried it. I really want to, so I need to hang out. Wherever you're hanging out, Seth. Cool.
Seth [00:22:06]:
I haven't got it outside of Seattle in a long. Had they had it in Washington for a while.
Kaisha [00:22:12]:
Okay.
Seth [00:22:13]:
All right.
Kaisha [00:22:13]:
I go up there to visit the office every once in a while. Okay. All right, we got this question in on YouTube. When poppy leaves, do you prefer leaving part of the leaf stem or removing all of it by pushing down towards the base like a lot of people do? Seems like leaving some leaf stem is less stress on the plant.
Seth [00:22:32]:
Absolutely. Just like we covered, you know, a quarter to a half inch minimum of that petty old, which is the leaf stem is good. If you got sharp scissors, that's great using your thumb. But basically, that part at the base of the pettyle where it connects to the stem of the plant, is evolutionarily designed to eventually drop that leaf in the fall. So once we cut that petty oil, we're not inducing that oxen response and not stretching it out. And you'll notice, too, a lot of times on those branches that you popped that out, you get the formation of more smaller veg leaves on different parts of the branch, which is not what we want when we're doing that.
Kaisha [00:23:11]:
All right, so, yeah, keep doing what you're doing out there. Cool. Okay, we got this one on Instagram. Rocketbud farms posted four foot lights over five foot tables and commercial facility. Thoughts? I think they're checking to see if that setup sounds good.
Seth [00:23:28]:
Yeah.
Kaisha [00:23:29]:
Detail on that.
Seth [00:23:30]:
Yeah. But when we look at light density, there's the traditional optimal, which is a four foot wide by four foot light over a four x four area below it, or a single fixture. HPS. But either way, we're looking at a four x four spread. Now that we've been experimenting with this at large scale all across the country for a long time or several years now, we're seeing running a five foot spacing on lights is okay. So ending up with 5ft between your two rows of lights, a four foot light over a five foot bench is okay. Me personally, I don't like five foot wide benches because I'm not usually getting enough extra plants on there to make it worth it. And also, it's a lot harder to reach into the inner canopy and work on the plants, particularly if your workforce isn't super tall.
Seth [00:24:14]:
That's been my experience on the five foot wide benches. If I'm running those, I'll often see that after we go and do a big deleaf in a big room, I can go look at the center of the tables where I actually do really want better deleafing because I don't have any light coming in from the aisles. And it'll just not be done as well because people can't physically reach in there as easy without damaging other parts of the canopy that they're reaching past. That being said, four foot wide lights on a five foot bench just fine. Not an issue. The only thing that might happen is you could potentially not be maximizing your light spread as much as physically possible. However, depending on your power availability that you have for the room, the size of the room, and then what your HVAC setup is, that might be the logistical limit of how far you want to push it in, putting lights in that room. Plus, if you already have the stuff, that's like 90% of it, right? If you've already bought the stuff, it will still work.
Seth [00:25:13]:
So, yeah, I'd say you're solid. Probably. In your case, if you've got rolling benches, really be diligent about lining them up under your light rows every time you leave the room and make sure no one's leaving a gap or has shifted the tables over so they're more in some of that dim overlap area.
Kaisha [00:25:34]:
That sounds like great advice. Thank you. All right, you mentioned HVAC. We got this question from Matt from Australia. Could Seth or Jason give their thoughts on pressure within HVAC controlled indoor grow rooms and the relationship to stamata mechanics? Back in the day, we were taught that negative pressure in a grow room is achieved by air exchange setups, inlet outlet fans, et cetera, created optimal conditions for stamata to work to achieve optimal plant processes. Now that HVAC sealed indoor grow rooms are used, what pressure is created by the HVAC. Negative, positive or neutral, does it actually matter for stomata? Love the podcast.
Seth [00:26:14]:
Thanks. Yeah. So basically, that's why we start looking at VPD vapor pressure deficit, and that's the balance between humidity and heat within the room and how it's affecting the stomata. So when the VPD is too low in our 1.0 or lower range, we're not having enough suction on the plant to get adequate transpiration. As we increase that VPD, by increasing the temp or lowering the humidity, then we can increase that surface, or not the surface pressure, but the air pressure, or negative air pressure pulling on the plant. And that's before, especially before everything was sealed and we were operating on exchange systems like a greenhouse. Basically, what we're doing is venting that humidity out of the room and lowering it so that we still get pressure to pull water up through the plant. And when we're talking about VPD, and that's why we didn't talk about VPD as much ten years ago, let's say, when we weren't dealing with sealed environments.
Seth [00:27:08]:
And now it's more and more important because it's another factor we have to dial. We can't just turn on the exhaust and make our problems go right out into the atmosphere. So anyways, in that lower VPD range, we're not seeing as much transpiration. And if you are going too high on the VPD, hitting that 1.9 plus range, that's when you start to see the stamata actually close up. So typically, how we approach it is we're shooting for, at any given time, 1.3, well, early in flower, 0.8 to 1.0, even down to 0.6. That first transplant day, when we're getting into mid flower, getting up into the 1.3 to 1.5 range, and there's a little variation. Any of this is always in ranges, because it's never static within the room, but these are some ideal values. And then, like I said, once we get to the end of flower, we actually do want to crank it up a little more, just to make sure we've got adequate airflow.
Seth [00:28:02]:
And we're kind of giving a safeguard for any of our mold susceptible strains. And then once we start to crank that up above that 1.6 to 1.9, like if we flower, especially if we veg a plant in a really dry environment and then flower it in that, we'll actually start to see a very different morphology on the thickness of the leaves, the size of the stomata and what the stomata look like when they form in terms, well, just like if you were to zoom out, not on an individual one, but when it's really dry, that's pushing the plant to go into what we'd call, like, true drought stress, which means it's going to form very small stomata. It's going to form leaves with a thicker surface and generally focus a lot of energy on optimizing what it thinks is a desert environment and having very little water, if a plant could think so. That's why we're always not pushing for the ultimate dryness the whole way through, because that's going to depress our yields, even if we're still able to grow those plants. I personally know growers who are in some bigger greenhouses, that because of their location, the way it's set up, they are operating in that high VPD range and as a result, they can maintain plant health. But their yield does suffer because they're not able to allow their plants to focus as much on floral development at as high of a growth rate. So there's a little overview, but just start doing some reading on VPD in controlled environments and I think that'll really get the gears turning for you.
Kaisha [00:29:28]:
Oh, that reminds me, we have an article on BPD. I will find it and drop it in the chat. It's a good one. Tyler and I worked on that. Tyler Simmons shout out we have our calculator too.
Seth [00:29:39]:
And the calculator, check it out. That really helps you put together what kind of a sliding scale you're working with. And then also, if you do a little bit of reading, you'll find out that we're also working with different types of lighting, different room temperatures. That's going to affect the leaf surface VPD, which at the end of the day is what we're really targeting. And that calculator pulls it all together, makes it really easy to understand what values you're looking for in terms of temp and humidity.
Kaisha [00:30:06]:
It sure does. It's a good one. I'm going to pull up that link shortly while we move on to this next question, actually, on the subject of VPD, booth by wrote in as it relates to VPD, when do swings become an issue? My dhu is a little overpowered when I gen steer, so I get like 0.4 kpa swings over 15 minutes periods. Is that something you should be concerned about?
Seth [00:30:30]:
So, like I said, it's always going to be dynamic. We always have a dead band, we don't have a static value. 0.4 is definitely pushing farther than you might is ideal. We'd like to keep it in that 0.2 range deadband. But 0.4 is not the worst, so long as your swing isn't constantly, especially in late flower, dipping down below 0.1, especially over 1.0, especially overnight. So especially if you're saying you have this issue earlier on in gen steering, that means there's a good chance you spec your dehuse out to try to prepare for all that increased humidity that you're going to be able to produce towards the end of flower. And this is something I see all the time on people's adventures with crop steering. Step one is I've got a grow space, I'm growing weed in it now.
Seth [00:31:14]:
I want to grow more. How do I optimize this? Well, suddenly, between cranking all of our inputs up and really manipulating the plant with irrigation, now we've produced a level of biomass that might be 200% more than what we were producing before. And that's just throwing a lot more humidity into the air. So right then, immediately your money goes towards dealing with that so you don't rot out part of your crop. The hard part is when we move those small plants in, there's just not that much transpiration happening and not that much humidity going into the air. And the end solution is either more granular control. That's why I always recommend when people are upgrading their DHU systems, go with more smaller units, so you have the ability to switch them on and off in phases. That way you have more individual control.
Seth [00:31:58]:
And then also, if you're at a point where that isn't really the most feasible, we've got a single big one. That's where we start looking at humidification systems to help balance that.
Kaisha [00:32:12]:
All right, thank you so much for that. I dropped links to our article and our VPV calculator as well. All right, keeping it moving here. We got this question in from slabs on Instagram. They want to know, how do we determine if a plant is a tetraploid? I have a male with four branches on each node. Could it be visually determined?
Seth [00:32:35]:
Yeah, sometimes you're looking for traits like that. Four branches on each node easily could be you can get a microscope out, look down close enough, and try to find some cells that are dividing and start counting chromosomes inside the nucleus. You can also send it off to a lab for testing.
Kaisha [00:32:52]:
Looking at cannabis plants under a micro.
Seth [00:32:55]:
And if you want to make sure you can get a hold of a substance called culticine that you can treat seeds and plants with that forces them to become tetraploid.
Kaisha [00:33:07]:
Damn south has all the resources. Look at this. I love it. All right, thank you. Good luck out there, slab. All right, we got this question on Instagram. We do get this from time to time. Do you have any suggestions on helping strains that genetically turn purple? Turn purple? It's been the biggest issue under LEDs to turn strains purple.
Seth [00:33:28]:
Yeah, this is a super common thing. And I love all the genetics questions that are coming up because I think one of the biggest challenges with our current set of genetics that have been developed for indoor cannabis production, primarily, a lot of breeders, especially if they've been at this for a long time, have been doing it in a smaller setting, and typically with HPS lights. I know a lot of people that still use HPS, and for good reason. The spectrum on them is great, and also that's what they're used to using. It's easier to get the purple, it's easier to get everything you're looking for. So we're selecting plants for those conditions, and then when we take them into the LED rooms, they're not necessarily as easy to get that expression because we've changed the spectrum and we've also changed the heat range that the plants experience. And one of the main things that's, I think, kind of missed in that switchover is our environmental parameters as far as ambient room temps actually change quite a bit when you make the switch from HPS to LED. So if you were used to running a certain strain, especially late flower at 75 in the daytime and 65 at night, under HPS, that plant was actually experiencing a lot more than a ten degree differential on the plant surface.
Seth [00:34:39]:
With LED, especially if you have good airflow in the room, we're seeing average plant surface temperatures that are four to five degrees lower than the ambient room temperature, whereas with HPS, it's exactly the opposite. Anywhere from three and rarely six. But three to five degrees above ambient room temp is pretty average. And you can feel it when you go into the two different rooms. If you go into an HPS room and you hold your arm out under the light, you're going to feel some nice warmth. If you go into an LED room, you hold your arm out under light, you're just going to feel whatever airflow is going on, and that's really the difference. So with the HPs, most of the time, our plants, well, not most of the time, especially in the last two weeks when we're running that diff, 75 in the daytime probably is equating to more like 78 to 81 on your plant surface, on your leaf surface temp. Whereas with those LEDs, if I'm running it at 75 now, my plant surface temp might be 71 72.
Seth [00:35:30]:
And so instead of a ten degree diff in that led room, I'm only getting a five or six degree differential. And the overall cold isn't what does it. It's that variation between hot and cold during the night, day and night. So if we can't get as much of a spread on there, we're not going to see nearly as much purple expression.
Kaisha [00:35:51]:
Thank you for that. All right, well, happy breeding all looks like a lot of good breeding and genetics activity happened out there. All right, B town dropped a question onto YouTube. They want to know when my p two s stack Ec, would it be okay to push runoff with every p two in bulk phase?
Seth [00:36:10]:
So it depends on what kind of Ec we're talking about and what your baseline is. If we're running down close to that feed Ec or slightly below it in the root zone, every time we add water to the block, that's a higher EC than what's in the pot. That's where we're going to see it come up a little bit. If you're already at a fairly higher EC state, like let's say you're feeding at a 3.0, but our baseline is five or six. That's when we might want to push a little runoff in those first couple of P two s. But I would highly guess that if that's what you're seeing, we're running in a lower EC state in general. And it's just that anytime you're adding water to that media, the EC is going up anyways. So if in p one, your EC goes up along with your water content, you can probably expect to see the same thing in P two.
Kaisha [00:37:00]:
All right. Yes. Thank you for that answer and that question. Okay, we got this one in on Instagram. Someone writes, my ro is broken and I need to wait 20 days for a new one to arrive. My tap water is 0.2 EC. Not that bad. What possible problems might I expect with your tap water?
Seth [00:37:22]:
It just depends on where you're getting it from. Is it coming out of a well local to where you're at? Is it processed city water? What are we dealing with? If it's just well water, there's probably a good chance that it's just fine. It might be a little higher in ph than you want. Like around here, our water comes out a lot of times between seven and like 8.2, which just means that I need to pay attention to my EC, my ph, after I mix the salts and put in an appropriate amount of ph down. So that'd be the first step, is like, hey, you're at 0.2 Ec. We know that that's probably. Excuse me for a second. Probably some calcium, magnesium, and a few other free goodies that we might actually want to be in there.
Seth [00:38:03]:
So that might be just fine. What I would do is mix up a few gallons at your 3.0 or whatever you typically are going to feed at, check the pH, see if you are going to need to amend it more or less than you typically would with your ro as far as pushing that ph up or down. And then also remember, if your tap water comes at a really high ph, where you're typically going to use phosphoric or sulfuric acid to push that down. So if I'm having my tap water come out at 8.0, I might end up putting in enough phosphoric acid that I'm actually altering that NPK ratio. So keep that in mind. And then otherwise, if it's just city tap water that has been chlorinated, put it into a res, throw an airstone in it, and don't use it for about 24 hours. If you want to be on the safe side, try to keep it dark, out of light. And in the mid 60s, as far as temperature goes.
Seth [00:38:54]:
But throwing an airstone in and waiting 24 hours is generally enough time to gas off any amount of chlorine that might be damaging to your plants. And the last thing to check for is like good old fusarium. If your water supply is contaminated with bacteria, you might have a problem, but other than that, you're probably okay. There's a lot of commercial facilities out there that have actually moved away from using ro because the filtration is expensive. It represents a bottleneck in their production process where, hey, we've got to filter a stock ro tank, maybe we don't have room for an ro stock tank that we then mix out of into other tanks. And a lot of places I've talked to have really kind of moved away from it and not really had a problem. But the biggest thing is clean water, no bacterial contaminants, and then making sure we're not looking at a high level of carbonates or anything like that. That's going to cause some fallout with your fertilizer.
Seth [00:39:51]:
So mix it up, be careful. Just pay attention to the details and you'll probably be just fine.
Kaisha [00:39:58]:
Oh, my gosh. Great advice. Okay. Good luck out there. I know we're going to rapid fire. Seth, you good? You want to keep going? You ready? Okay. Love it. We got this question on Instagram.
Kaisha [00:40:09]:
Santa buds twelve wrote, when you reach desired poor water ec, how do you work your p two to keep it stable? And they're looking for during veg and regenerative feedings.
Seth [00:40:22]:
So once you've achieved that poor water ec that you're at, make sure you're not pushing any runoff with your p two s. If your poor water ec goals are enough above your feed ec that afternoon. I wish I had a graph to pull up. I didn't prepare that today. But typically we're going to see at those p two s is not a lot of fluctuation because we're putting on such a small volume of water. So if we're looking at that chart, typically right before we water in that p one, that's when our EC should be the highest in the root zone. And then after we water, we should see an inverse reaction where that ph, or not that ph, that EC drops down while the volumetric water content is going up. Once field capacity is achieved, as long as we're not pushing a bunch of runoff through, we're putting on very small amounts, one to 3% of what that pot's volume is.
Seth [00:41:09]:
So really that EC should remain. It'll be a little bit like a jigsaw, but fairly stable throughout your p two feedings and then start to rise back up overnight as we see that overnight dry back.
Kaisha [00:41:23]:
That was a great question. Awesome. Thank you for that. Okay, this one, we've got a few questions in the bank. And just for everybody who's on with us live, now's your chance to ask some questions. Live. Seth, he's on a roll. He wants to hear from you.
Kaisha [00:41:37]:
Tommy and the trees wrote in. Should an indoor flower room with supplemented CO2 be burped to bring in fresh air at all? Or is that just wasting CO2?
Seth [00:41:50]:
You don't really need to burp it particularly. No, but it depends on also what your CO2 accumulation is looking like. And this is why crop registration always with everything, CO2 being one of them, one thing to really consider, and this is where burping might does come into play. For some sealed indoor growers that end up being not sealed over time is their nighttime CO2 levels start to go up exponentially. So there's a balance in your system of providing enough CO2 in the daytime, and then realizing that, hey, I've got to cut off supplemental CO2 completely after the lights go off because photosynthesis isn't happening, the plants aren't using CO2 and in fact they're respirating. And the roots, that's breaking down sugar, that's using oxygen. So if at any point overnight that CO2 level becomes way too high, and we're talking about well over 3000 ppm, then we'll start to see some decreased growth on the plants because they can't respirate and they can't take up water and nutrients quite as efficiently overnight. So if you're going to be dealing with that situation, making the choice, make sure you get a decent monitoring system that can let you know if your levels are getting excessively high overnight.
Seth [00:42:59]:
And that can definitely be frustrating because a lot of us have a CO2 control system that has a nice little readout and controller on the wall, but no time series data to tell us what happened last night. So for me, I just got the new climate one and that's how I'm monitoring it overnight. But otherwise, it just depends. If you're already using a system that gives you that insight, that's where you'd start to call it, because you do want our nighttime CO2 to be the same or slightly lower than the daytime CO2.
Kaisha [00:43:33]:
All about that time series data around these parts. All right, cool. Thank you for that. I just realized we have a few questions that are referencing you specifically, Seth, so I'm just going to go for it. This one came in a while back. Seth, I know you like your organics. What would be your approach in a four x eight bed? Rather execute dif or a cad instead of water scarcity. Thanks.
Seth [00:43:56]:
In like a four x eight bed, there's a few different ways to go. You want to build up a good mix. So we're looking at all of our compost materials that we're putting in there. I'm a big fan of think. And if you're not familiar with knife, create natural farming. That's using a bunch of different compost and fermented products that you can make yourself to basically create a living soil that you're feeding all the time. That's my preference. However you can keep it.
Seth [00:44:24]:
I've grown outside in my home for my vegetables. Sometimes I get lazy and I don't want to do the whole Knf technique. So I'll go and amend my soil with manure. A little bit of lime, just nothing special, little kelp, little seaweed, the standard some bone meal, blood meal. We can go on a long ways with this list, but one of the key things with growing organically is understanding the decomposition rates and breakdown of that nutrient source and how long it takes in situation for those nutrients to become plant available. And then also looking at your irrigation strategy and making sure that, hey, when we're running something like an organic living soil, we're not pushing these extreme drybacks because that's pretty detrimental to the microbial and fungal life in that soil that we're relying on to break down these bigger component inputs and make plant available nutrients. So those are the two biggest things to keep in mind. If I'm going to be putting some compost and manure in there, for instance, what is the decomposition rate of that? Do I want to amend the soil right before I plant? Or in a lot of times do I want to amend it 30 to 45 days ahead of time to make sure that the nutrient composition is where I want it at that point in the plant's lifecycle.
Seth [00:45:38]:
So, hey, we're going to have a lot of nitrogen availability for about four or five weeks after planting. And then based on the amount I put in, I should be able to see that value taper off. Now, I'm not testing it. This is all theory that you can read, but there are great resources out there to help you find out. And especially if you're buying compost anywhere unless it's from your neighbor, a lot of commercial compost producers will have that information available about how long in amended soil it takes for their product to break down and give you what you want. And that's part of why, when we look at traditional outdoor growing, putting guano on your plants at different points in time, guano is pretty high in PNK availability. So we're putting that on mid flower to try to give them a boost. And we know that that particular source doesn't take that long to break down versus other sources of potassium we might be putting in the soil.
Seth [00:46:29]:
So part of the reason that I don't push a lot of commercial growers to go organic is because of the extra level and attention of detail it takes to really nail down a consistent product and yield. So if we're talking about living soil beds indoors, one thing you might find is that if you want your living soil beds to last for a very long time, years on end, and remain disease free, that's going to be a lot of work and it's going to be really hard to completely plan a business around it. With very consistent yields, you'll probably see between different amendment practices. And obviously at that point you're probably feeding some compost teas variation. We might see three runs after we first bring that bed in that are great, or that first run isn't too good. By the third, we're hitting pretty much the prime in the life cycle of that soil. And then probably the saddest realization is that in agriculture in general, once we're planting the same species into one bed over and over and over, we're leaving that root mass behind when we harvest. And that does break down over time, but it also leads to accumulation of different diseases and viruses in the soil that are specific to that plant.
Seth [00:47:45]:
So if we're looking at like coco for instance, why is coco a great growing media? Well, not only is it really low in CEC, does it have the moisture content we want, it's sustainable. Also, coconuts are not very closely related to cannabis, and they don't really share a lot of diseases. So you're not really likely to get any kind of coco that's coming in. I mean, barring that it's been contaminated naturally, coconut husk is not going to house fusarium, for instance. So that's why. Another reason, in big commercial settings, we're changing out our media. Every run is just, it's a hygiene factor. That being said, if fungus nats don't bother you, you'll probably be okay for many runs in your beds.
Kaisha [00:48:35]:
I don't know. I have a feeling like if we devoted a whole episode just to your organic growing practices, people would be super down who appreciate that. Walkthrough, carpe our grow me here on the hangout. Dropped a question here. Would you recommend using a ph buffer like potassium carbonate, even if my feed ph is well within range after mixing, I'm in one gallon coco inline irrigation with dosage arrays, if that comes into the equation.
Seth [00:49:01]:
So, I mean, when we're talking about adding buffers to anything, a lot of that comes from using something with any kind of reasonable CEc. So if we're looking at what we'd call a traditional soil or soilless mix that holds on to some of that EC, we are going to look at probably wanting to have a buffering compound in there. And especially like if we're looking at organics, for instance, I'm mixing in potentially azima gypsum lime, depending on what the ph of that soil I'm working with is. But that buffer is going to help insulate me from the fact that I maybe don't have good control over my ph once it's in the root zone. Like, I can feed it a certain pH. But now, once I get into, let's say, living soil, I've got a lot of interactions going on that adjust the ph in that millimeter around the root zone, around the individual root that the plant actually experiences. And that's where having a buffer is nice. You have some more level of control of what's going on on that level in the root zone.
Seth [00:49:56]:
However, in our coco or Rockwell production practices, we're typically able to use that feed ph and EC input to really precisely control what's going on in the root zone because we don't have additional reactions and organisms in there causing that ph to change dramatically after we put in our feed pH. So when everything's going smoothly in a hydroponic system, part of the reason we use hydroponic systems is just to have complete control over what's going on in the root zone. And obviously, that's always easier said than done. There's a lot of small practical parts that come into controlling it on that level. But if you're growing in straight coco with salts, not typically needing a buffer.
Kaisha [00:50:42]:
There it is. Awesome. Thank you guys for those questions. All right, we got this one in from fonti over on Instagram. They want to know, how do you go about raising relative humidity in a homegrown to get into good parameters for VPD?
Seth [00:51:01]:
Cheap ultrasonic humidifier.
Kaisha [00:51:04]:
Bam.
Seth [00:51:05]:
Yeah. In a hydrometer. Hydrostat, you don't need anything fancy. Hopefully, you're only having to raise your humidity early on in flowers, so you're not potentially getting droplets in the air that are going to land on your actual flowers, but just a cheap humidifier. I like the ultrasonic ones, particularly for home use. They seem to work great. The only caveat with any humidifier you buy, you might want to run distilled water or ro through it, because if you run tap water through it, you might get some scaling and lack of efficiency over time. That being said, they're not terribly expensive.
Seth [00:51:41]:
And you can go onto places like Amazon and actually just get a little ultrasonic ring and drop it into a bucket full of water and build your own. There's a bunch of budget ways to do it, and I personally like that approach quite a bit because those little rings are not expensive at all. They're cheaper than going to Walgreens or whatever and buying your cheap humidifier. And that allows me to turn any bucket that I can put a fan on top of into a humidifier, so not too complicated. There's obviously fancier systems out there, misting systems like people use in aeroponic applications. But I like to keep it as simple as possible, especially in the home grow, where I don't necessarily have an optimized drain set up in the room, where if I have a leak, it might be a big issue and I'm actually damaging the house or whatever structure I'm in. I don't have an extra level of insurance to make sure that everything runs smooth. So keep it simple, and you probably don't need nearly as much as you would think.
Seth [00:52:43]:
But getting sensors in there and understanding what's going on is really what's going to help at the end of the day.
Kaisha [00:52:51]:
That's right. Keeping it simple is always a good way to go. Amazing. Thank you for that question. We just got this question in the chat. Do you monitor your orp in a commercial setting, or do you generally keep your water cold?
Seth [00:53:05]:
Both. So, Orp, I want to see what's the oxidation reductive potential, but basically, how clean can my water be and how reactive is it against microorganisms? And also, I want to keep that water down below 70 degrees, because even above 70 degrees, if I get that orp up, it's still not carrying as much total dissolved oxygen as the water is when it's below 70 degrees. So that's why I typically target that 65 to 68. Even down to 60 is okay. But mid 60s is where we see the most dissolved oxygen. I like to use fish. That's another example there, just because I like fishing. But there's a reason you see trout in a cool mountain stream, not a dirty pond.
Seth [00:53:51]:
And the prime reason for that is that cool mountain stream has a lot more oxygen in it. It's colder, it holds onto the oxygen better, it's flowing, it's actually dissolving more oxygen in it more regularly. And that's why mid 60s, temperature wise, with an airstone in it, is exactly where you want to be. And even in commercial settings, we see people trying to use oxygen injection systems and all kinds of things. At the end of the day, simplicity is the best thing. I've seen some anecdotal and some examples of where people have used oxygen injection to produce some great results. But at the same time, you got to look at the total growing system. If you've been using oxygen injection, you're using a porous media and watering 16 times a day, let's say in a hugo, well, it's probably the 16 irrigations more than the injected oxygen that's actually doing anything there.
Seth [00:54:43]:
And the other part about it, when we're talking about OrP, a big thing is fuserium. So if we've got stuff like fusarium in our water supply, the higher I can get that Orp, the more likely I'm going to be able to actually kill that fusarium and maintain a sanitary environment in my injections or in my irrigation system.
Kaisha [00:55:01]:
You come for the crop steering, cultivation knowledge, and you get to learn about trout as well. Truly, you're like a renaissance man, Seth. Amazing. Okay, thank you for that. We're going to go ahead and answer this one last question. If we weren't able to get to your question today, don't worry. We got a little bank, and then just come back next week. We got you.
Kaisha [00:55:19]:
This one came from B town. They had a beginner question. We started talking about runoff at the beginning of the show. They want to know, is runoff percentage based on input, irrigation, or substrate volume?
Seth [00:55:32]:
Substrate volume. So with VWC, we're always looking know the best way to think about it is if you had a gallon pot. Think about it as an empty pot with a gallon volume in it. And if we're at 60%, we're filling up 0.6 gallons of water in that gallon pot. So we're always talking about how much water is in the pot versus the total holding capacity of the container, not the total capacity of the media itself.
Kaisha [00:56:01]:
Amazing. All right, well, thank you for that. We're wrapping up just a few minutes early because I just wanted to run down this little last order of business before we go. Like I mentioned earlier, you are at hall of Flowers Ventura today. Keep an eye out for Jason Francis. And, Noah, if you are at spannabis, our head of marketing, Christian, is out there doing the thing. And then later this month, Haley and Noah are going to be at any can in Boston March 22 and 23rd. I will be at connect Sacramento on March 26.
Kaisha [00:56:32]:
So aroya is out there on these streets. Hit us up and say hi. You were just at indoor, right, Seth?
Seth [00:56:40]:
Yeah, yeah. I saw a few people I knew there. It was a little different vibe than like, MJ Bizcon, but I would encourage anyone out there that's looking at getting into the commercial space to check out that particular event over MjBizcon, because that's a lot more focused on the actual growing technology and science behind growing at scale in facilities and really isn't obfuscated by packaging and everything else that goes into the cannabis industry in general. It's very focused on just growing. It helps expose you, too, if your whole agricultural experience is inside the cannabis realm. It's really an eye opener into how much technology and equipment is shared between general horticulture and cannabis and how much a lot of the companies that we actually like also engage in agriculture outside of cannabis.
Kaisha [00:57:40]:
She's evolving. It really is amazing to see. It does.
Seth [00:57:43]:
And you can go see some panels and learn from people who learned how to get rich off of growing spinach or strawberries. And I think that's really good insight for those of us that are used to growing a much higher value crop. Like, hey, what are some strategies people are doing to make money on things that really are far less valuable than cannabis, but not necessarily a whole lot easier to grow? What's the strategy there?
Kaisha [00:58:07]:
I love it. Yeah, these conversations are so great. And any opportunity we have to meet people in person, we really love to do that. So be know, tag us on Instagram, send us a little note, let us know you talk to us. We definitely want to stay in touch. Seth, you rock. Thank you for holding it down solo in studio. Shout out to producer Chris for holding it down with me.
Kaisha [00:58:28]:
And then thank you all so much for joining this week's episode of Aroya Office Hours. To learn more about Aroya, book a demo at aroya IO, and our team will show you the ins and outs of the ultimate cannabis cultivation platform. If you have any crop steering or cultivation questions you want us to cover, drop them anytime in the aroya app. Email us at sales aroya IO. Send us a DM via Instagram, Facebook, or LinkedIn. We definitely 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. See you at the next one.
Kaisha [00:58:57]:
Thanks, everybody.