You end up doing this? If so how’d it go?
I did not, I didn’t dare change to much my first run at the new grow. I’m thinking I’m going to switch to a custom mix to have better control.
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Had anyone ever seen this before?
We’ve got about 1/3 of the moms in the veg room doing this, I’ve never seen it before at home under cmh, these are under hps lights that are dimmed to 60%.
Temp is 81, humidity 56. With a leaf temp of 77. That’s giving up a vpd of 1.14.
Also have been having a issue with hollow stems, we’ve been giving them a calcium foliar the last two weeks and that’s been helping, I’ve got some boron on order I’m going to add to the foliar as well.
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Looks like it wants nitrogen to me… I obviously assume your feeding it the right amount, but that’s what I assume just looking at it. Seems like a cut that was accustom to a feed schedule and just got it changed. But it also looks more mature than that. Have you started watering them more than usual? Is the cultivar new to you? Maybe it’s more sensitive to moisture. Is the problem persistent or sudden?
Also cannabis stems are almost always hollow. Pith autolysis happens when the plants are a fast moving/growing cultivar. The only time I ever have a really hardy “stick” is low and old growth.
It’s on some strains I’ve had for two years and some newer ones, it’s nothing I’ve changed except for the room, I think the room is more dialed in and the plants just can’t quite keep up with the growth.
What I understand to much nitrogen and not enough calcium can be a cause for hollow stems. If a plant is on point they shouldn’t have hollow stems.
This white truffle is not affected and loving life. It’s a beautiful leaf but i wasn’t very happy the wife had picked it off lol.
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I would just keep an eye on it, if it just presented after a room switch maybe it’s just a hiccup. But then again, if you never had hollow stems before it could be a sign of something… I want to say 70% of the cultivars I’ve grown have had basically blow gun stems. Only the lower stalk/trunk was ever pith filled.
Some Athena veg… 9 pointers on 1.5 footers.
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@Medicine.grower From all the evidence I have and seen, hollow stems aren’t caused by nutrition. All the content I have read associated with hollow stems being attributed to nutritional issues have no quantitative data behind them.
I saw this posted on Instagram a couple of months ago (I apologize I didn’t record the account name, just screenshot the image because it is really interesting for discussions like this – if anyone knows the OP please point it out!). The OP was pretty much pointing out the observation that hollow stems are most commonly not derived from nutritional issues. To show this you can see the contrasting tissue of youngest mature leaves between hollow and full piths.
This matches the data I have on the matter as well (although that’s from clients so I cannot share publicly). Tissue from hollow and full pith plants can often look very similar, often the hollow plants’ tissue can look even better.
From my experience, hollow stems often have to do with growth being too aggressive often with water uptake/transpiration happening too fast. This also matches the observations you have posted (correct me if I’m wrong of course).
I would suggest to increase your RH to lower your VPD to 0.9 kPa and increase your EC. These in my experience should lead to fuller piths without having to change your nutrition. Increasing CO2 might also help, but I still have no strong evidence on this.
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Thanks for the reply, we added some calcium chloride into our veg foliar for the last few applications, we took some cuts today and the stems were almost filled in now. I’m not sure if it’s for anything to do with the calcium or not though.
I’m not sure if you guys have seen slownickle on ig but he’s got a micronized calcium that I’m going to test out, he’s saying it’s supposed to help with the hollow stems, and the reviews seem to be good.
I for sure agree with you that the quick growth is what is bringing this on but I’m only seeing it in certain cultivars.
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In that chart you can see that the analysis is indicating the stem that is more hollow has significantly less calcium and more nitrogen than the hollow, so it would seem apparent that it might be nutrients in that specific photo, no?
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Not quite, the Ca is still very high, more than 4%, in the tissue with the hollow stem. This is more than ample Ca, most dicots only need 1-2% Ca in leaf tissue to be healthy.
In my tissue database I have hollow plants with 6.5% Ca as well.
What I wanted to point out is that there is no deficiency in the hollow plants, all its nutrients are pretty normal.
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Okay, that makes sense… I need to get more into understanding the exact nutrient profiles that are considered healthy in the samples.
But additional Ca can help fix the issue, not because its lacking in tissue, but perhaps because of how it affects water transport.
In cannabis Ca often affects processes unrelated to Ca nutrition. There havent been studies to understand these mechanisms yet.
But for example, what cannabis growers describe as “Ca deficiency” has - in my experience - never ever actually been a true low Ca in tissue, but it can be fixed by adding Ca. It can also be fixed by addressing the true issue, which is commonly some root zone imbalance.
Just because something can be fixed by a nutrient doesnt mean the issue is fundamentally nutritional.
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Ph plays a role in calcium uptake also, it could play a role
It’s hard to find calcium acetate in Thailand, but when it’s available, I’d like to know. Calcium Acetate vs. Calcium Chloride What’s the help? If we put 1 gram of water per 1 liter of water, how many ppm of calcium image|231x500
I’m sure 300+ ppm of Chloride in solution is going to be great!
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This is an interesting matter. Sodium chloride has been shown to decrease the quality of cannabis flowers, but increases of chloride using potassium chloride have not. The toxicity of chloride is related with nitrate antagonism - as they are both anions - but at a stage where you want almost zero nitrate uptake, it might not matter much.
The real question is, do you really need more Ca? At week 7 in flower most cannabis leaves will already be >6% Ca and the media will often contain high amounts of accumulated Ca from the often previously very high Ca feeds. I don’t see the point of adding Calcium chloride at this stage, even if all calcium nitrate is removed.
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Did you notice the numbers of what Athena labeled on the bags it’s different then what actually it’s inside? In the bag ratios it’s 5:1 I think here it’s 2.5:1 
,or actually i didn’t remember right what it’s on the bag,coppee needs to go higher if your in coco and depends on the boron needs to goo.higher I believe,yea I think Athena it’s not the best option in the market
We’ve switched from Athena to a custom mix, only did one run on it so far but at 1/3 the price and the grow looks just as good I’m happy.
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