Curled Leaves Question

[BostonFisher]

We're on our second indoor grow. In a 4x5 tent with a 600MH and exhaust fan and regular osculating fan. Soil in pots. At about week 2 some of our leaves are curling up. See pic. Any idea why they would be curling? Happening to about 1/3 of our plants. Plants otherwise look good. I've searched and seen info on over watering or possibly heat. Maybe our light it too close? I appreciate advice if anyone has seen and solved for this before.

 

[NHWhites]

Check for pests

 

[BostonFisher]

Check for pests

I did no sign of any.

 

[NHWhites]

I did no sign of any.

Did you also check the roots?

 

[BioStimz]

Looks like a potassium-deficiency from heat-stress.

Avoid cal-mag for a bit.

Maybe go with a kelp/fulvic mix to bump the potassium up.

What's the pH at?

~

 

[MW7945]

pH?

 

[Monster762]

Yeah if you don’t see bugs I would go with heat. How close is the light? And what temps and humidity do you hit. Highest temp lowest humidity? The other plants don’t look the same though. I would scope real good for bugs too. Not just a quick look.

 

[BioStimz]

I highly doubt it's an insect issue.

Heat is likely why it's curling upwards.... but the yellowing edges (unless I'm just seeing it wrong) indicates potassium deficiency from the stress.

 

[BostonFisher]

Thanks everyone we're gonna move the lights up. It was about 80 in there. See if that helps.

 

[chemistry]

I would go down the heat route first.

 

[Monster762]

I would go down the heat route first.

Yeah I agree you don’t want to sacrifice light if you don’t have to. 80 is a little higher than plants like. But some do ok in 80. I’ve seen most do better around 70. 65-75 where I try to stay at. When I see 80 I uaually kick the a/c a little more.

 

[Monster762]

Yeah I agree you don’t want to sacrifice light if you don’t have to. 80 is a little higher than plants like. But some do ok in 80. I’ve seen most do better around 70. 65-75 where I try to stay at. When I see 80 I uaually kick the a/c a little more.

It’s crazy cause outdoor I seen em like 90 degrees but indoor they don’t. No idea why.

 

[brazel]

Is this amended soil? Or you feeding them? This is big info that would help people troubleshoot. Like watering, if it's amended soil then you shouldn't have run off, so that eliminates over watering problem. If it's a properly builts soil than that eliminates your deficiencies.
It doesn't look heat or potassium to me but that's a guess

You could probably figure it out, so more than one plant has curled leaves? Were those Bunched together or mixed with the other ones. Would you say your Technique on watering is pretty much equal on all the pots? Is it the same soil? We're all the ones with curls underneath the same light?

Look at these things and more!

1/3 plants? What does that tell me if I don't have total plant count?

Let's say you have 12, so 4 are bad. Are those four mixed in with the other 8?
If so why would one plant taco but the two beside didn't? Look at the light, is the light directly over the taco plant then it might be light, but that's one thing that we know so far. but let's say it's not say it's over the two that aren't taco well that's weird for the other one to taco when the light is over the other ones that are not?
Got it? Cool rad man
Tell us your findings



Unfortunately no one for sure can say what's going on without knowing all the variables.

Put your hand at the top of the plants, palm facing down, do you feel heat on the back of your hand from the light?

 

[BioStimz]

the yellowing edges (unless I'm just seeing it wrong).

I think i saw wrong. At second look, I don't see any yellowing around the curls, and your other plants look fine. I'm thinking it's just a genetic mutation.

GG #4 is known to get all twisty/curly, but it's a trait that recedes within a few weeks.

What strain are you growing?

~

 

[jumpincactus]

Here are some common problems when marijuana leaves are curling.

1. Too much marijuana fertilizer
   The most common cause of marijuana leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is overzealous use of marijuana plant food. In relationship to factors such as marijuana plant vigor and rate of growth. Leaf burn is often the very first sign of too much marijuana fertilizer.
   A hard, crispy feel to the marijuana leaf frequently occurs as well, as opposed to a soft and cool feel of a happy pot leaf. Back off on the amount and/or frequency of using marijuana fertilizer. Too much marijuana fertilizer can also burn the roots, especially the sensitive root tips, which then creates another set of problems. Note - as soil dries, the concentration of the remaining salts rises further exacerbating the problem.
2. High Heat
   The marijuana plant is losing water via it’s leaves faster than what can be replaced by the root system. The marijuana leaf responds by leaf margin cupping or rolling up or down (most times up) in order to conserve moisture. A good example is reflected by the appearance of broad-bladed turf grass on a hot summer day, high noon, with low soil moisture levels - the leaf blade will roll upward/inward with the grass taking on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat in the marijuana grow-op and concentrate on developing a large robust root system. An efficient and effective root system will go a long way to prevent heat induced pot leaf dessication or marijuana leaf margin curling. One short episode of high heat is enough to permanently disable or destroy leaf tissue and cause a general decline in the leaves affected, which often occurs to leaves found at the top of the cannabis plant. The damaged pot leaf (usually) does not fully recover, no matter what you do. Bummer in the summer. One can only look to new growth for indications that the problem has been corrected.
3. Too much light
   Yes, it’s true, you can give your marijuana plant too much light. Cannabis does not receive full sun from sunrise to sunset in its natural state. It is shaded or given reduced light levels because of adjacent plant material, cloudy conditions, rain, dust, twilight periods in the morning and late afternoon, and light intensity changes caused by a change in the seasons. Too much light mainly serves to bleach out and destroy chlorophyll as opposed to causing marijuana leaf cupping, but it often goes hand-in-hand with high heat for indoor marijuana growers. Turn down the time when the lights on in your marijuana grow room. If you're using a 24 hr cycle, turn it down to 20 hrs. Those on 18 - 6 marijuana growth cycle can turn their lights down two or three hours. Too much light can have many adverse effects on marijuana plants. Concentrate on developing/maintaining an efficient and robust root system.
4. Over Watering
   For marijuana growers using soil, this practice only serves to weaken the root system by depriving the roots of proper gas exchange. The marijuana plants roots are not getting enough oxygen which creates an anerobic condition inducing root rot and root decline with the end result showing up as leaf stress, stunted growth, and in severe cases, death. Over watering creates a perfect environment for damp-off disease, at, or below the soil line. Many times marijuana growers believe their cannabis plant is not getting enough marijuana fertilizers (which it can't under such adverse conditions), so they add more marijuana fertilizers. Making the problem worst. Not better. Often problem 1 and 4 go together. Too much marijuana fertilizer combined with too much water. Creating plenty of marijuana plant problems.
5. Not Enough Water
   Not only is the marijuana plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic marijuana growers may need to water from the bottom up until moisture levels reach a norm throughout the medium. One of the best methods in determining whether a marijuana plant requires watering is lifting the pots. The pots should be light to lift before a water session. After watering the marijuana plants lift the pots to get an understanding how heavy they've become fully watered. If the pot feels light to the lift - it’s time to water. Don’t wait until the soil pulls away from the side of the pot before watering. And of course, leach, once in a while to get rid of excess salts. These are the five most common problems marijuana growers encounter when growing cannabis. Correcting the problems early will save the marijuana plants, but may reduce overall yield. With practice and experience these problems are easily overcome which will then enable the marijuana grower to produce fantastic marijuana plants. With heavy yields.

Marijuana SeedsTop of page

 

[BioStimz]

It doesn't look heat or potassium to me but that's a guess

After a second look, I'd say that's a solid guess. Heat-stress should be accompanied by some degree of discoloration/yellowing (or at least it has in my experience), and none of the other plants look affected whatsoever.

 

[brazel]

After a second look, I'd say that's a solid guess. Heat-stress should be accompanied by some degree of discoloration/yellowing (or at least it has in my experience), and none of the other plants look affected whatsoever.

And heat is air temperature. The others ain't taco but they could be more resistant to heat. Need more info! When did this first start, how long has it been? Heat stress doesn't happen instantly.

 

[MidwestToker]

Second thread this week with with this problem if it's a GG#4. https://www.thcfarmer.com/community/threads/is-this-heat-light-stress.92134/#post-2015106

 

[Dick Terpene]

Humidity.

 

[BioStimz]

Humidity.

Can't be.... the surrounding plants are un-affected.