Some fan leaves curling at the edges

[phxazcraig]

I'm trying to recognize a problem in the early stages and head it off. In the past couple of days I've noticed a few leaves starting to curl at the edges, particularly on one leaf on the plant closest to a rotating fan. (Wind damage in part?) I have two other plants (of 4) with very preliminary signs, or whole leaves twisting sideways a bit.

I'm trying to find all probable causes for leaf edge curling. My guess at this point is heat stress. Here are answers to the questions in the Read Me First post.
Hydro Growers:
(I'm going in a prepared coco coir mix from Roots Organics.)

1. Are you growing from seed or clones?
seed

2. How old are your plants?
seeds sprouted Jan 7 into Jiffy pots which immediately went into solo cups. Transplanted to 3.5 gallon air pots at about 8-10 days after sprouting.

3. How tall are your plants?
6-7 inches, but they've been topped a few days ago at the 5th node.

4. What type of hydro system are you using?
DTW, homemade.

5. What brand/type of nutrients are you using?
Silicone (then 1 hr delay), Cal/mag, then FF Big Bloom and Grow Big (hydro version), then humic acic (Diamond Nectar) and a bit of Yucca powder.

6. What is the Ph of your nutrient solution?
6.0. Controlled via pH Down and a Bluelab controller

7. What is the PPM/EC of your tap water?
It's very high (513/1087 - Phoenix AZ has very hard water)

8. What is the PPM/EC of your nutrient solution?
The current batch is 870/1853. The EC is a bit higher than desired here.

Runoff from this morning's watering was 814ppm and 1.717 EC. In the past the PPM went up a bit, and EC tended to go up by about 0.300. I'm still dialing in the amount of water to fertigate, but I'm guessing about a gallon for each watering split between 4 plants. I get a bit under a gallon runoff. I run the reservoir pump for 30 seconds at 6am when lights come on and 4:30pm. The lights go out at midnight for an 18/6 schedule.

9. What is the temperature of your nutrient solution?
75F

10. Does your PPM/EC show a rise or fall when you do your daily PPM check?
pH is tightly controlled by the Bluelab controller, so it stays right at 6.0 where I set it. I have not checked EC daily, but I don't think it is changing.

11. Does your pH show a rise or fall when you do your daily check?
Stable

12. Do you foliar feed or spray your plants with anything?
None

13. What kind of lights do you use and how many watts combined? (HPS, MH, fluorescent, halogen, incandescent "plant lights")
I use a 600w HLG 600r.

14. How close are your lights to the plants?
Varies, but about 2 feet for now. I am limited on height of the tent, so I make do by controlling power via dimmer and measure with PAR meter. Currently running about 450 PAR at the tops of the plants.

15. What size is your grow space in square feet?
4x4

16. What is the temperature and humidity in your grow space?
Temps range from 77 at night to 84F during most of the day when the light is on. 6-inch duct fan comes on at 80F and off at 77F. RH usually around 40-45% during day, up to 75 at night when fan finally shuts off. Being in Phoenix I have very little control over humidity, some over temps. There is a humidifier in the tent, and the room door is usually closed. (Closed during winter. Too hot in summer to do that, so even less humidity control then.

17. Have you noticed any insect activity in your grow space?
None

18. How much experience do you have growing?
This is my third crop over past year, first in Coco.

 

[mysticepipedon]

19. Do you have any pics?

 

[phxazcraig]

 

[phxazcraig]

There is a shot of the worst one.

 

[phxazcraig]

View attachment 1212331

The inside edges of the biggest leaves are curling inward. This also happened to a lesser degree to the three other plants. Those spots on the leaf on the right side also showed up about the same time. This also correlates to me refilling the reservoir with a new, stronger batch of nutrients on Friday. Figuring the plants were under stress, I've raised the light a bit, turned the power down (400 PAR), and diluted the remaining water (5-6 gallons?) in the reservoir with about 3 more gallons of distilled water, dropping the PPM under 800 and the EC down to 1.4. I then doubled the amount of water this evening to flush out the coco a bit. Got about 2 gallons out, not sure what went in, but not 5 times that.

Incidentally, it seems the worst-hit leaves also developed very red stems recently. Any correlation between stem color and health?

 

[GanjaJack]

Light might be a little close.... and your nutrient solution is a little higher temp than I would like. I'm thinking if you raise your light a little bit, you can lower the temps in your res and also stop the leaf curl.

You said : "I've raised the light a bit, turned the power down (400 PAR), and diluted the remaining water (5-6 gallons?) in the reservoir with about 3 more gallons of distilled water, dropping the PPM under 800 and the EC down to 1.4. I then doubled the amount of water this evening to flush out the coco a bit. Got about 2 gallons out, not sure what went in, but not 5 times that."\

So, you've already done that.... LOL!

Now just have to wait it out to see how it responds.

 

[phxazcraig]

I don't know if I have a deficiency or overabundance of something, but it seems more likely I overdid something. Buy I might be low on calcium in the way I mixed my nutrients then diluted them with distilled water. Some of the leaves on one plant are sort of twisty. But they are growing really fast too. When I mixed the notes last time, I mistook Big Bloom for Grow Big and put one in at 50% greater strength than intended. I then panicked a bit and diluted the mix down to the correct amount, but it threw the other ratios off. That's before I diluted again after the symptoms appeared. Ppm was up to about 900, EC at 1.8.

 

[phxazcraig]

Herr are some more images try I need to show curly edges and overall health.

 

[visajoe1]

tripper. dont let the pots sit in their runoff or you'll get salt build up soon

 

[phxazcraig]

tripper. dont let the pots sit in their runoff or you'll get salt build up soon

Air pots, which themselves have a 1 inch gap underneath, into self-draining saucers, into a sump pump. I think my runoff % is high. I'm in the process of measuring it, but I'm putting more than 2 gallons a day through 4 pots. There is a lot of runoff, and the pots are heavy.

 

[ComfortablyNumb]

Wind stress. Aim the fan at the wall, not the plant. As long as you can see the plant moving slightly, that's all it needs at this stage.
The wind draws the humidity and transpiration away from the leaf edge and the light stress causes the edge to fold over.
So, lower your light dimmer by 5% or raise it 6 inches.

 

[phxazcraig]

Wind stress. Aim the fan at the wall, not the plant. As long as you can see the plant moving slightly, that's all it needs at this stage.
The wind draws the humidity and transpiration away from the leaf edge and the light stress causes the edge to fold over.
So, lower your light dimmer by 5% or raise it 6 inches.

Thanks, that's been done. I know the leaves closest to the fan look the worst, but all four plants show signs of leaf curling. Still, they are really growing fast! I topped two of them for the second time (took 7th nodes as well as 5th). Leaves are enormous.

Raised light a good 6 inches, and set PAR to 400 or so at the top of the plants. Decided to lower EC even more (and was getting low in the reservoir) so added another couple of gallons of distilled water. Might have gone dry during the morning feed, and I don't have another 10 gallons of water ready to mix up yet. Anyway, EC is around 650 now, and EC down to 1.2. One more feeding tomorrow morning, and I will clean the reservoir and mix a new batch of nutes.

 

[phxazcraig]

Water usage estimate: Overall it looks like I'm putting 3000ml in twice a day and getting 2000ml of runoff. That's for four plants. I measured the input to one pot at 700ml. I measured 2000ml output from all four. So it would appear I have 66% runoff at this stage. I've had the timer set to pump water for 30 seconds twice a day. I'll try setting that back to 20 seconds and see what happens.

Plants are almost 4 weeks old now and growing very strongly. I'm wondering how much water others give their coco pots over the course of a week? I'm going through my 14 gallon reservoir in less than a week.

 

[jguit]

I'm wondering how much water others give their coco pots over the course of a week?

I'm too tired to do the math but in 1 gal fabric pots and at the stage your plants are at now, I was giving approx 250-500ml per plant daily with runoff.

I'm now approaching the 2nd week of 12/12 and am feeding each plant approx 1750ml daily (250ml 7 x day)

 

[phxazcraig]

I'm too tired to do the math but in 1 gal fabric pots and at the stage your plants are at now, I was giving approx 250-500ml per plant daily with runoff.

I'm now approaching the 2nd week of 12/12 and am feeding each plant approx 1750ml daily (250ml 7 x day)

What size reservoir do you use, and how often do you fill it?

 

[jguit]

What size reservoir do you use, and how often do you fill it?

If there's one thing i'm going to change in my setup next run, it's going to be the reservoir size. I'm using a 17 gallon tote (for flowering 4 plants) and wish i had gone bigger. I find that i'm filling it around every 3 days or so but i'm also taking some of the feed from my reservoir for other plants.

 

[phxazcraig]

Update: As far as I know, leaf edge curling was due to having the light too close, too bright and temps of 86F or so, combined with low humidity. But with coco, everything seems to be happening so quickly that I'm worried problems can accelerate just as quickly.

Anyway, I turned down the A/C, raised the light, and lowered the brightness to a PAR of 400. Just in case, I diluted my nutrient reservoir to get the EC down (around 1.5 now). pH steady at 6.0 throughout.

OK, here are some images of the plants at the one month mark. Sour Diesel seeds germinated on Jan 7. I've topped them at the 5th and 7th nodes already. Based on my understanding of indica and sativa, these sure look like indica. Very squat with very broad leaves.