What causes new leaves to curl down?

plants look al healthy , except those leaves which are curling down. plants are in soil, on 24 hour light. temp is ok. lv a bit low.

made some pics:



there is a strange purple color on the leave also, as you can see (i hope)

Ph looks high. See how to test soil ph in my signature below.

best i can figure

best i can figure

1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plant?s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the root?s epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips, which then creates another set of problems. Note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem.

2. High Heat - the plant is losing water via it?s leaves faster than what can be replaced by the root system. The leaf responds by leaf margin cupping or rolling (up or down) 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 in and the grass will take on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat and concentrate on developing a large, robust root system by practicing sound plant culture. An efficient and effective root system will go a long way to prevent heat induced leaf dessication and 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 plant located near HID lamps. The damaged 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.

what size of a pot are you using?....looks a little small for that size of plant.

id agree with the ph, it looks like a mg or zinc deficancy....

i have had a similar problem with my nigerian nightmare . i'm just a rookie, but i THINK it was cause by overfeeding (as latitude has indicated above).

Blueberry is noted to have this genetic trait sometimes and can not be fixed. My pheno had it. But in your case it looks like PH or a nute problem- expecially combined with the colour. Just my .02 cents. Good luck!

TGT

That is over feeding no question about it .

the curl in the leaves and the lime green color in the new growth tells me that.
The purple in the leaves might be alittle ph problem but you must becareful when adjusting ph in a plant that has signs of over feeding.

FLUSH THEM OUT !!!!!
Then worry about Ph .

If you adjust an incorrect ph in a plant that is showing fert stress you can fry them pretty quick.
FLUSH ,FLUSH,FLUSH

keeko, 7 liter, but they are only 2 weeks in these pots. but.....ok, i think i will put them in bigger pots today.

I'd say too much nitrogen

It's allready been said above but there's many reasons for leaf curling. Most common would really be "the claw" which you get from too much nitrogen. Then there's the typical Haze leaf curl which is (from what I read) due to too low rh. But I don'r think you're growing a Haze.

I'd go with the too much nutes thing, so flush with twice the amount of water as you have soil in there, which'd be around 13ltrs :wink:

i checked ph from the soil. that was 6,1. So i have been giving them only water last days.....see if they recover.

Let us know how you get on :wink:


We took a joints worth of your MF with us when we left, smoked it last night, still very impressive

thnx. i 'll let you know what happens...

at first it looked they were recovering, but they still have those claw leaves. i tried a few things now, but i cant figure out their problem.

what causes leaves to look like that? it aint the heat and they arent overferted also, because when i start giving them water for a few days, they start showing def's.

some more pics. I added pottasium yesterday, cause the only thing i could find about leaves curling down, was a P def.

Hmm, the leaves show signs of Mgn defficiency, but have a leaf curl like there was too much N

I think carrying on as normal might be best because flushing and then starting to feed again takes a ciouple of days to show effect. Sorry can't think of anything else

i am on my second grow of nigerian nightmare and i still have the same rams-horn downward leaf-curl as i did on my first grow . i have ruled out overheating (temp. at canopy is only about 80f tops) and overfeeding (havent fed anything for weeks, they are pretty much feeding off soil only). i am not too worried about it. perhaps it's just a trait some strains have ? the last grow produced a healthy crop, even with the leaf curl, and this grow looks like it will as well . nonetheless, if anyone can shed any light on this i would love to hear it.

The claw leaf shows up here if I over water. and it is in the new growth where the curl occures.

I only grow clones most the time, and can have 2 clones same age - one is claw leaved - and less healthy - the other is "normal"

It gets worse if it's on the cool side and I water a little too early - before the plant gets thirsty. They don't need as much water or nearly as often at lower temps. But it's easy to do anytime. Happy plants get THIRSTY before they are watered - not so much that the leaves droop; idealy - just a little bit before the plant starts to droop.

I'm thinking - your tending to BARELY overwater - not swimming lessons time overwatering - on average- a day earlier than the plant really wants overwatering. If the plant can't make it till next watering on what it has - then is the only time I will partial water - but I think they like to wake up dry and get a good drink early - it's the wake up dry part, if it's moist and you water - the top leaves revolt

Moppel said:

on 24 hour light.

Click to expand...

If your using hid, use 18/6.