So we are having unseasonably hot weather here in Denver and the temps today are up to 97 right now and could go a little higher. I have 3 Autoflowers in 5 gal Smartpots that I transplanted from Solo cups 6 days ago and I have 3 photo plants still in Solo cups that are close to being ready to transplant, (they are draining the Solo cups every 2 days). Is it bad to keep them in direct sunlight in this heat and should I move them to shade or just let them be?
Young outdoor plants in 97 degree heat?
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garybo
Well-Known Member
@jokerlola , nice seeing you.
If it is do-able, I would certainly put the ladies in the shade every once in a while. Perhaps keep them under a tree or a lean-too, especially for their age. I'm told 10 hrs is all they really need, that's for photoperiods though, I would assume that auto's should be similar.
I grow in FL and we have similar temps, though we have higher humidity more that you guys, I think. I personally put my ladies under cover every evening with a fan on them and next morning out into nature they go during the day. I grow in fabric pots, I guess that's the same as a smart pot.
Good luck with your grow.
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Yeah, Smart Pots are fabric pots. I have a covered porch that the plants will get morning sun but be in the shade after 1pm. On days with predicted temps in the 90's, I can put them under that porch.
Normally when we get these high temps, my plants are pretty established and can tolerate it but maybe I should have been shading them from the high 90's temps all along.
Yep on all points but up to you on whether to worry or just let be.
Plants have a preferred temperature range. If the temperatures get to cold or to hot the plant slows down, almost stops, and returns to active growing processes after the temperatures return to the preferred range. For many, many types of plants it seems to in the 50s on the low end and the upper 70s to mid 80s at the other.
With the expected temperatures I figure that the plant starts to enter a dormant stage around 82 and pretty much stops at about 85. There is still transpiration but the plant is not processing as much of the nutrients it has taken in and is doing next to nothing with the photosynthesis that is still slowly taking place.
The big problem as I see it is the soil in the containers gets a lot hotter than optimal. When everything cools off the plant goes back to business.
I look at these situations and decide whether it is worth the effort and the risk if I pull a muscle or drop something. The plants still in the cups would be moved to shade as soon as possible if it was me. For the most part if I have to move a larger container I will find an area of 'dappled shade' and put them there for the length of the heat wave.
garybo
Well-Known Member
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That is really interesting and may explain my first grow. I was given some cuttings but I had never grown cannabis before. I got the cuttings rooted and got some 5 gal Smart Pots and wound up with 5 plants I was growing outside in the summer. Because we hadn't put a fence up yet, I had to keep the plants on the east side of my house against the house so that neighbors couldn't see them. They only got morning sun until about 1pm and then they they were in shade for the rest and hottest part of the day. Those first plants grew really nice and big and I had a big yield. We put a fence up the next year and I was able to put my last 3 grows out in full sun all day long and although I have had some really good grows, they haven't grown as big as those first plants despite having full sun access. Here in Denver we are in the high 90's for many days during the summer. So maybe with that kind of heat, my plants that now grow in full sun are somewhat stunted compared to my first grow that never got exposed to the direct sun in the hottest part of the day. I think I'm going to have to start putting my plants on the east side of my house on days with predicted temps in the 90's.
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- #7
SmokingWings, So you think it's a good idea for me to move my plants to shade when the temps hit 85 and over?
For instance today the temp right now is 87. It would be better for the plants to be in shade now? And any plants that are still in Solo cups or other small containers definitely should be moved to shade?
My plants are in 5 gallon fabric pots with handles so they are easy to move.
Sueet
Well-Known Member
When I have movable plants outside on a day like this, I watch them.... once the leaves start drooping I move them into light or dappled shade. Solo cups I would definitely move to shade immediately and make sure they have plenty of water.
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- #9
Ok. Thanks.
From doing a little searching, it looks like protecting plants from high temps is even more critical during flowering. My 2020 Super Lemon Haze plants wound up with airy buds and I think that was probably due to high heat with direct sunlight during flowering.
We used to have such different weather here in Denver. We rarely broke 80 in May. Then stayed in the low 80's during June and didn't get into the low 90's until mid July, with only a few days in the upper 90's and maybe only 1 or 2 days 100 or over (if that even happened) and then August would be a slow slid back into the low 80's with Sept mostly in the 70's. Now e almost always start hitting 90's in May and are pretty consistently in the upper 90's all through July and August and often into Sept. This year we hit 90's in early May and now in early/mid June, we've hit 100 twice!
What @Sueet brings up. Light shade or dappled shade when high temperatures start, especially with bright sun.
Those small Solo style cups will heat up fast and get to the same temperature as the air. The 5 gallon container, whether a solid plastic or a plastic cloth pot with handles, takes longer to get hot plus the larger amount of soil does cool off a bit as the water evaporates.
cbdhemp808
Well-Known Member
Hi @jokerlola ! I don't have much experience with high temps like that, but I do have a little. Some thoughts... water more, put some coco coir as mulch on the surface of the soil, use coir in your soil mix to help water permeate the pot and also hold moisture some, mist the plants in early morning and evening, put a wrap on your smart pots that reflects heat – you can use white Tyvek, or reflective bubble sheet, or a cut up white feed bag, etc. ... held on with clothes pins. Good luck with your grow!
Excellent idea. Especially useful should be the coco coir that is ground up it looks little strands sort of like the way peat moss looks.
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- #13
I will look into this. What I have been doing on days predicted to be over 85 is placing the plants where they get full sun until about 2pm when the house shades them. If it's going to be below 85 I put them where they get full sun all day.
cbdhemp808
Well-Known Member
Your pot size (5 gal) should be sufficient to provide enough water for the day, even if temps get into low 90s. With mulch on the surface, and wrapping in heat-reflective material, you may not need to use shade, unless temps get above say 95. But, observation is the best guide. If you see no wilting or heat stress evidence, you're probably OK.
Here's what I observed when temps got too high in my greenhouse. I call this alligator leaf. Some phenotypes were more susceptible to this.
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- #15
I generally have never seen problems with excess heat with past plants but we haven't had temps at or over 100 at this time of year like this year. Usually my plants are much bigger by the time we start having these kind of temps when we normally do in the middle of July.Your pot size (5 gal) should be sufficient to provide enough water for the day, even if temps get into low 90s. With mulch on the surface, and wrapping in heat-reflective material, you may not need to use shade, unless temps get above say 95. But, observation is the best guide. If you see no wilting or heat stress evidence, you're probably OK.
Here's what I observed when temps got too high in my greenhouse. I call this alligator leaf. Some phenotypes were more susceptible to this.
I did have plants in the past that wound up having airy buds that I think were from excess heat during flowering. And during my very first grow when I had to kind of hide my plants from the neighbors and they wound up being shaded during the hottest part of the day. They seemed to grow better and bigger than the next 3 years that I could keep them in the sun all the time. If cannabis plants stop growing after temps get over 85, that might account for this.
