gordonian said:

So I have a some grape kush that is in week 3 of flower. All the leaves in the upper third of the plant are yellowing starting at the leaf tip working its way back. . I am in coco 2 gallon pots feeding 1500ml 3 times a day with roughly 20% runoff. room is 78 degrees with 62% RH. nights are running about 5 degrees cooler. Mills nutrients ph to 5.85 E.C. 1.6. Lights are 4 feet off canopy. I did a slurry test and P.H. was 5.8, but with a blue lab soil ph probe the pots were reading 5.3-5.7., not sure which is accurate. Any ideas what it might be?
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Two.Bears said:

could the plants be root bound? 2 gallon pots are small

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Two.Bears said:

the traditional wisdom

3 gallons fine for auto flowers.
5 gallon fine for most indica
7 gallon or larger for Sativa.

to me i think she needs a new pair of shoes.

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Thejoeybrown said:

That’s for soil. Holds way less oxygen.

Coco is a different animal. You don’t start seeing the potential of coco until those roots fill that pot out the whole way.

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stonestacker said:

How long have you been growing? Have you grown in coco before? are you supplementing CA?
In my grow when my plants start to yellow like that I up my CA. Through trial and eror thats what works for me.

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Dunge said:

I'd spray it with calcium chloride foliar.
see tomato end rot spray.
If it improves, solved.

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Thejoeybrown said:

Transplanting would do only harm and no good IMO. You look to be about 3 weeks into flower and the next weeks are most important. Why disturb the rootzone. Trust me 2 gal in coco you can grow as big a plant as you can fit without getting root-bound

You are feeding 3x a day so it shouldn’t be getting dried out.

Personally I think everything your doing feed wise sounds good so shouldn’t be locking it any nutrients. .
Are the stems purplimg?
It looks like could be mag or potassium.

But that would most likely mean a lockout because all those should be enough in your base. What’s your runoff ppm?

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stonestacker said:

How long have you been growing? Have you grown in coco before? are you supplementing CA?
In my grow when my plants start to yellow like that I up my CA. Through trial and eror thats what works for me.

Click to expand...