Lower leaves yellowing in the 4th week of flower, and older buds edges look burnt

[Greenpassion]

I have a number of issues here. I have several plants in the 12 12 in various stages of flower. The one that is in the 6th week of flower has almost burnt looking Leaf edges not completely at the top but in the upper part. It also has yellowing leaves and very spindly weak branches. And I have several that are only in the beginning of their fourth week of flowering, and their lower leaves are becoming a pale yellow. I've done the best I could taking pictures. I'm using Botanicare nutrient line and I'm wondering if they're not getting enough Cal Mag? I've also been giving them Bud swell, the bat guano along with the Botanicare nutrient line. I've been giving them between 4 and 4 1/2 mil calmag. I need help here.

 

[Greenpassion]

Here are more photos of the leaves from the plants that are in their fourth week of flower

 

[Toker1]

Soil or hydro? What has the PH been like this grow?

 

[Greenpassion]

Soiless promix bx, and I've been watering them at 6.2.

 

[Toker1]

For soilless I follow hydro.. which means you need to let the PH fluctuate between 5.5 and 6.5. If you are hitting 6.1 every time, your plant won’t absorb all the nutrients it needs.

 

[Greenpassion]

Oh. I guess that might be what's wrong. I hope that's all it is! Did you check out the pictures of the other one it has the edges of the leaves looking like they are dry or burnt? They are not the uppermost leaves closest to the light but a few sets down. Many of the leaves deeper inside the canopy are actually crispy and brown now. I don't want to lose her!

 

[Toker1]

If you are using the Botnicare feed schedule found online and you are letting your PH fluctuate a bit, like we previously discussed, then the new growth should be coming in just fine after that.

 

[Greenpassion]

Thanks Toker1. I'll keep you posted...

 

[Toker1]

No prob!

 

[Greenpassion]

Toker1, should I then do my next watering at 6.5 since I have been watering at 6.1, and then the watering after the 6.5 go down to 5.9? Something like that? Or should it be less of a jump?

 

[Toker1]

It depends on what your root zone PH is like. For now put in 6.5 and see what the run off tests at. That will tell you what to do next.

 

[Greenpassion]

Do I put in 6.5 nutrient water and check that run off? Or do I put in 6.5 plain pH water and test that run off? I'll have to do this on 7 plants.

 

[Toker1]

Plain PH adjusted water will work fine.

 

[Greenpassion]

Ugh. Okay just to be sure I'm straight on this. I put in plain pH to 6.5 water, Check that run off. And if it's comes out a low number like 5.2 or something like that then the next watering I would water it 6.5 nutrient water or even higher than that nutrient water?

 

[Toker1]

Might want to check your medium’s manufacturers for their recommendations on upper and Lower limits for PH. But yes, essentially you got it. I would think keep flushing at 6.5 in until you are at least at 6.0-6.3run off in that case. But check with them to be sure.

 

[Greenpassion]

I hope I'm not trying your patience here, but I do appreciate the help for sure. What if my run off water turns out to be 6.5? Does that mean that it's not a nutrient problem and something else then?

 

[Toker1]

If PH is 6.5 then I would say to lower it closer to 5.5. You need PH to range for hydro.

 

[Toker1]

If you only ever adjusted to root zone ph to 6.5 I would be concerned about ability to absorb Phosphorus, Manganese, and Boron.

 

[Greenpassion]

Okay. I guess my concern around watering them with just plain pH water is that they have to go another 5 days or so to dry out before they get any nutrients at all. That won't hurt them?

 

[Toker1]

If the PH is off they won’t be absorbing nutrients anyway.
I have only grown using soil and deep water culture. So maybe a soilless grower or coco grower could assist better with that specific question.