Is it heat stress or not??

I am currently growing 11 plants in a 4x3 closet with a 400w HPS lamp on an 18/6 timer, and a fan running 24/7. They are 3 weeks 3 days old. Current temp is at 74.8F but this is only after toying around with my lamp from 16 to 19 inches and seeing what worked. I also moved my fan so it blew on the lamp directly instead of directly on the plants. (Plants are still swaying though)


Average temperature at the time of the problem was running between 79-81.8 degrees with the light on and 64-67 degrees with the light off, and humidity constantly between 40-60%.

I spritzed the plants once a day with a 40% club soda 60% water solution. I made sure to only put a fine mist over the leaves and not to have any droplets.

They were recently transfered from 6 inch round pots to 8in square pots a week ago. None recieved any damage during the xfer. They are given 12oz of water every other day and are also given regular miracle grow fertilizer at 1/4th of the reccomended dose on the bottle at the same time. They are also given a half dose of superthrive at the same time. (Sometimes one or the other is skipped though) They are in regular miracle grow fertilzed soil.

The problem is that the leaves on some of the plants have been curling (upwards and downwards) and turning a dark green. Some of them show signs of cracking. I believe this is a heat stress problem due to the elevated temperature earlier in the growth cycle. Can anyone verify this and do you think the changes to the light distance/temperature may have already fixed it?

If not - what should I do? Do I cut the damaged leaves off?

The temp sounds good if it really isnt pushing past 80 but if I were you I would lessen my feedings. Feed every other day with nutes (Low strength with Miracle grow because of the potential to burn them) and feed with just PH balanced water in between feedings.

Just put your hand under the light. If its good for you, its good for your babies

You have any pics? I wouldnt clip the leaves unless theyre completely yellow or theyre over I think 50% damaged. Not to sure on that though...

AKRevo47 said:

You have any pics? I wouldnt clip the leaves unless theyre completely yellow or theyre over I think 50% damaged. Not to sure on that though...

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I'm about to go and grab some pics and I'll be back in 30 mins or so.

jayblaze420 said:

I'm about to go and grab some pics and I'll be back in 30 mins or so.

Click to expand...

The pics are named for what each shows. You can't really see the darkening of the leaves but it is almost a hunter green. The cracking and folding should be obvious and you can even see some of the other leaves in the background for comparison. Also there is a pic of another plant that just seems droopy. Finally, there is a pic of the best plant as well as one of the entire grow room.

I believe I have provided all the information possible. We were very thorough in our research, but this is our first grow.

I don't see anything that I think should be cut off due to damage.
Given the said temps, it should not be a heat problem.
Do you have a way to check the ph of soil and water?
Are you waiting until the containers are really light before you water? The droopy leaves could be over watering.
As for the Miracle Grow I can't say I've ever used it, but I think for ferts it's always better to go less and build up from a defiecientcy than to go too much and kill the girlies.
From the pics, I can't see the problems you described---except the drooper
Remember, these ladies are strong. Don't worry too much. Good Luck.

We don't have a ph tester. Although we've looked into it - it just didn't make sense w/ all the money in it already and besides... how far off can tap water be? It's drinkable, etc.

I have seen some tap water come out at 9.3 and you can get a good ph meter for $35.00 to $45.00 which seems cheap enuff to make sure your plants stay healthy. And as far as your plant problem I think you have a nitrogen overdose you might want to cut back on that MG and flush your soil. Mg soil has nutes already that last for 2/3 months so adding more MG nutes is over kill.

Hey Jay, Not sure where you live, not asking.

But I live in New York, My tap water comes out at 8.3 and sitting overnight comes to 7.5

Depending on what you soil ph is, depends on what your water going in needs to be.

As you are still in the early stages of your plants life, it would be a very good Idea to invest evan 5$ in
PH test strips, or evan the liquid ph test kit.

If you do not know, or cannot tell your plants ph level, or at least the waters ph level. Its hard to decipher what the problem may be.. or could be.

To me, it looks like your being too observant. Stop spraying the plant every day. Spray it once or twice a week.
And watering every other day sounds ok, but wait intil the top half inch of soil gets dry to a crisp.

They were recently transfered from 6 inch round pots to 8in square pots a week ago. None recieved any damage during the xfer. They are given 12oz of water every other day and are also given regular miracle grow fertilizer at 1/4th of the reccomended dose on the bottle at the same time. They are also given a half dose of superthrive at the same time. (Sometimes one or the other is skipped though) They are in regular miracle grow fertilzed soil.

The problem is that the leaves on some of the plants have been curling (upwards and downwards) and turning a dark green. Some of them show signs of cracking. I believe this is a heat stress problem due to the elevated temperature earlier in the growth cycle. Can anyone verify this and do you think the changes to the light distance/temperature may have already fixed it?

If not - what should I do? Do I cut the damaged leaves off?[/quote]


From my almost exact experience, - your drowning them and poisoning them. MG soil has everything needed till you start flowering. i was watering every other day with 1/4 mg nutes, couple weeks into it i had the craziest curly leafs thought i killed them. now just plain water when they need it. 1st grow, go get a ph/light/moisture meter and local home supply store for a few bucks and use it till you become familiar with soil conditions. i was amazed at how wet the "dry" soil looked.

Over fertin'em

Well based on the pics do you think the plants need pruning? Would it help them to cut the sicker, older, large fan leaves off so the plant can focus on vertical growth? We are less than 2 weeks away from flowering stage. Would this set them back any or is it too late alltogether to start pruning them.

PS - If you look at the last photo you can see a plant on the bottom left that was cut down significantly. This was done as an experiment. I'm thinking that it was too much? Anyone know of any good pruning videos to watch?

I will talk to my partner about cutting the extra ferts and saving the superthrive for times when the plant is stressed (ie: after pruning). I have also tried to find pruning vids on youtube and google but no such luck. If there isn't a decent vid can someone give me detailed instructions on how/what to do? I tried searching this forum for some posts related to it, but they don't really describe exactly which spot to cut into. Can you just cut anywhere and it will grow in 2? That doesn't seem likely to me.

Mad rep to whoever responds w/ useful answer

i just left all my old leafs on. focus on the health new growth. let the plant recover a little before pruning. if you cut any part of the plant the next internode will most likely grow into 2.

I would just like thank everyone for the advice hope to hear more from you guys in the future!!!!!!!!!!!!!!!

Here is a simple guide by mogie
Fimming and Topping 101
https://www.rollitup.org/general-marijuana-growing/13820-fimming-topping-101-a.html

If you still need it.

bloop... said:

Here is a simple guide by mogie
Fimming and Topping 101
https://www.rollitup.org/general-marijuana-growing/13820-fimming-topping-101-a.html

If you still need it.

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Hell yea that was perfect.

We stopped w/ the extra ferts, but some of the older leaves are turning darker, and some even have purple from the points inward. Some plants continue to droop as well. What I don't understand is that if we were over fertin' them before - how can they be showing signs of a phosphorous deficiency? (That is what most people say the purple color is) Any ideas anyone?!

We got a pH tester and the tap water is below 6.8, and that's before it's sat out awhile. I'm guessing the pH is at or under 6.0 by the time it sits out and is put into the plant. Is that too far out of range? Today is supposed to be the end of veg for us. We are moving into flowering 2morrow as scheduled.

If you are liveing in the uk put your fan's on a timer at night it is too cold for the fans to be on during the 6 hour lights off.i would higher my lights a tad and take the fans of high if they have a high speed just till leaves stop curling .but this problem is either heat stress or the temp flux during lights off.if your plants look ok don't worry so much just higher your light see if it is heat stress.