Leaves curling upwards. Closing up.

Hey guys, need help.

One of my Zkittlez top leaves started looking very weird overnight. Leaves curling upwards and completely closing up. I never saw this before and couldnt find anything similar on the internet.


Its definitely not heatstress. The temps have been between 21-28ºC - (70-80F), this morning a bit on the lower side (18ºC - 64F). Humidity goes between 40% and 50%.

Light is a 600W HPS at 60cm (24in) away from the plant. Nutrient scheduled has been light..

Other plants look fine, just this one is looking weird all of the sudden.


Here's some possible causes that i can think of. Help me diagnose this please.

> Plant getting ready to sleep and/or had enough light for the day? Leaves started doing this some hours before lights OFF.

> Underwatering? I havent water in 4 days. Usually i water this plant every 2 or 3 days...

> Root damage? Last night i did some minor damage to the roots using a soil moisture probe.

> Too cold? This morning temperatures went to 18ºC (64F) for the first time. Humidifier was also ON. Usually minimum temp is around 20º C


Any more info i could provide, just ask.

Thanks

What medium are they growing in, what are you feeding them, pH ppm/ec ?

Moflow said:

What medium are they growing in, what are you feeding them, pH ppm/ec ?

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Biobizz all-mix organic soil. Organic bottled nutes. Feeding 1/2 of the recommended strength. PH at 6.5. Dont have EC meter.

There appears to be not much answers on the net re your problem .....
Plenty of suggestions tho.
Could be low pH locking out calcium, magnesium
A fan blowing on that one plant
Overwatering
Over feeding
Checkout @Renfro post below

I've a similar problem on a couple of plants that started last week. They're in a peat compost and homemade compost mix.
I suspect in my case the medium was too low in pH and too hot. I've never tested the pH of runoff or ec before but done it for the first time ever just outta curiosity. It read ~ 5.1 pH and an ec of 2.7-ish.
Here's what I decided to try a couple of days ago.
I flushed through with plenty of pH 7.2 water and foliar fed with npk nutrient with trace elements at 0.7 ec at pH 6.4
It's to early to tell if it worked yet but they haven't got any worse.

update: leaves got gradually better after lights went off. I also plain watered till run-off.

I've concluded it was light stress. Even tho my hps600W was 24in away, i just measured with a luxmeter android app and it turns out i was getting 100k lux or 1300 umol/s/m2 at canopy level. This amount of light at 18/6 was giving me a DLI over 80!

kodak91 said:

update: leaves got gradually better after lights went off. I also plain watered till run-off.

I've concluded it was light stress. Even tho my hps600W was 24in away, i just measured with a luxmeter android app and it turns out i was getting 100k lux or 1300 umol/s/m2 at canopy level. This amount of light at 18/6 was giving me a DLI over 80!

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Glad they are looking better.
Not sure about 1300 umols at 24" Lux meter apps aren't very accurate compared to a par meter.
Here a par map of 600 hps at 18 and 24" away

Did you just switch to flower??

Looks like a humidity issue. The leaves can't aspirate properly. Do you know what vpd is? If not look it up

green_machine_two9er said:

Did you just switch to flower??

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Its 4 autos and 1 photo. The autos just started to flower.

p0opstlnksal0t said:

Looks like a humidity issue. The leaves can't aspirate properly. Do you know what vpd is? If not look it up

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yeah i try to follow the VPD chart and i got a humidifier. RH% is around 40%

kodak91 said:

Its 4 autos and 1 photo. The autos just started to flower.



yeah i try to follow the VPD chart and i got a humidifier. RH% is around 40%

Click to expand...

Ya that's an issue

Moflow said:

Glad they are looking better.
Not sure about 1300 umols at 24" Lux meter apps aren't very accurate compared to a par meter.
Here a par map of 600 hps at 18 and 24" away
View attachment 4871484

Click to expand...

I had measure the 24in "by hand" so it might have been less then that, i didnt use a tape measure.

Thanks, i've seen that PAR map and actually have it bookmarked. Im aware that a Luxmeter app from android is not very accurate but i think its accurate enough to draw some conclusions. I just raised the lights, and PAR levels went from 1300 ppfd to 600ppfd.

Im confident it was indeed light stress. At least i hope so.

p0opstlnksal0t said:

Ya that's an issue

Click to expand...

u think 40% is a issue? I had way lower then that before without any problem. Most of the time is at around 50% tho. I have humidifier running 24/7

It's hard to tell from the pictures you posted but you might want to look your plants over closely for bugs.

@DoubleAtotheRON I think I remember you gave your plants quite a high pH to sort out low pH problem

xtsho said:

It's hard to tell from the pictures you posted but you might want to look your plants over closely for bugs.

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Its dust and ashes from smoking inside the growtent

kodak91 said:

Its dust and ashes from smoking inside the growtent

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Like I said I couldn't tell. But I've caught bug activity before that the grower was aware from posted photos so I always like to point out what looks suspicious. Glad you don't have bugs.

That dust and ash will get on your buds later in flower. You might want to stop smoking in there and if you're not filtering your intakes you should start. Keep that dust outside of the tent.

Good luck.

xtsho said:

Like I said I couldn't tell. But I've caught bug activity before that the grower was aware from posted photos so I always like to point out what looks suspicious. Glad you don't have bugs.

That dust and ash will get on your buds later in flower. You might want to stop smoking in there and if you're not filtering your intakes you should start. Keep that dust outside of the tent.

Good luck.

Click to expand...

Thanks. Yea no doubt, im always checking for bugs.. My intake is not filtered and dust gets it, need to improve that.

@Moflow only now i had the time to see that thread. Very interesting, thanks for sharing.

The leaves are almost back to normal, just a slight curl now. If the problem was low PH on the rootzone would it be solved this quick? I was inclined to think lightstress because how fast the leaves recovered..

Also, i have one of those cheap soil temp/ph meter with a probe, which isnt very accurate, but it was reading about 6.5 / 7 PH yesterday.

last update: Leaves back to normal 10 hours after "semi" flush and raising up the light.

Photos before and after.

Thanks for the replies guys.

Some of what I saw earlier looks like normal activity during “preflower stretch”. And it typically only happens during lights off.

don’t over react on this one and cause other unrelated issues.