Leaves turning yellow and getting spots

[AF420]

Hello everyone! I have 4 females on 2 week of flowering. They have grown perfectly so far but 1 week before changing the photoperiod from 18 to 12 light hours to start flowering i started noticing both yellowing leaves and spots on the lower fan leaves. This problem is getting worse cuz some upper leaves started showing same thing and the first affected leaves are getting worse. This is not my first grow but it is my first indoor with artificial lights. I have them with 400w hps and they eat all biobizz products and worm hummus. Everything organic. They’re planted in soil with coconut fiber, and hummus.

the pictures with the light on are the same leaves as the pics with light off. Lights off pics were 1 week before flowering, lights on today.

I don’t think it’s overfeeding but I don’t know for sure.

some advice would be really appreciated.

tks

 

[Campesino]

Looks to be some Ca And Mg deficiencies probably caused by the Coco (if it is not buffered). Are you adding anything for Ca and Mg?

 

[AF420]

I’m using only biobizz products and sometimes worm hummus. Two of them (Alg-A-Mic and Bio-Heaven) are supposed to have some Ca and Mg. I have been using these products with no complaints, they aren’t as good as Advanced Nutrients or other chemical products but these are organic and not as expensive as Advcd Nutrients

thnky you for your answer

 

[Redwasp]

Show the whole plant please.

 

[Campesino]

That is not going to provide sufficient Ca or Mg in Coco.
The Colloids in coco are naturally loaded with K cations. In the presence of Ca or Mg, they will give up the K and grab the Ca or Mg. This leaves virtually no Ca or Mg available to the plant. It is a good practice to buffer the coco by soaking it in a solution high in Ca and Mg prior to use. That allows these exchanges to take place without harming your plant. Once the Colloids are loaded with Ca and Mg it stops being an issue.
Your best option now is to increase the dose considerably of Ca and Mg. This isn't actually to feed the plant, but rather to satisfy the Cation exchange capacity of the Coco. I do not think those current products will provide enough.

 

[AF420]

[No message]

 

[Campesino]

Yes, Ca and Mg issues caused by unbuffered Coco

You say there are 3 parts to your "soil" mix. What would you say the ratios are? When was the last transplant?

 

[AF420]

I think its 70% natural soil, and the remaining 30% pure coco fiber and hummus. Also i added some mycorrhizae. I transplanted them only once from a plastic cup to those final pots. It was in a very early stage. Maybe 50 days ago i think

 

[Campesino]

Odd that it would show up this late, but still confident based on symptoms.
Were you giving them something with more Ca and Mg during Veg?

How big are those pots?
"Natural" = dug up from ground? Is it Sandy/loam/clay? rich in organic matter? How well does it drain?

 

[Redwasp]

They look weepy to me. To much water. To little water(new growers rarely the issue.) To much nutrients. To hot? Need more info.

 

[AF420]

During veg i fed them with the same biobizz products that I’ve always been using with no complaints, nothing extra besides worm hummus sometimes. Not sure about the volume of the pots but I asure you they’re big for an indoor. Soil was store bought, by natural i was referring that it has no perlite or vermiculite or anything extra besides the normal organic matter, it’s pretty much like what you have in your backyard but it’s rich in organic matter. I placed some stones in the bottom of the pots for drainage.

 

[Campesino]

Yeah, I was starting to suspect root issues, but the mix he describes should drain well.

 

[AF420]

Some of the leaves are droopy cuz I was out the last three days and forgot to water them, but besides this time I give them good amounts of water and nutrients, I always check ppm of the solution to make sure I’m not over or underfeeding and I’m also using the same amount of nutrients that I’ve always been using in my previous potted outdoor girls. This is my first indoor. Temps are 19-22 C at night 24-27 C during day. Humidity was high in vegbut now it varies between 35% to 75%.

 

[Campesino]

Back to Ca and Mg. Need to find a way to up the dose. Realize that Ca and Mg have a big impact on EC, so you may have to lower dose of base nutrients to accomodate it.

Perlite in particular would be good to add in future for drainage. There are signs that plants are drowning somewhat as Redwasp suggests.

 

[Redwasp]

Indoors add at least 20% perlite. If it doesnt have it may be oxygen deprived.

 

[AF420]

I use oxigenated water 3ml per liter each irrigation. Not sure if it helps

 

[Campesino]

Oxygenated water will help

 

[Redwasp]

Sorry i get confused. This is not a pure soil grow. Or am i mistaken again. Lol

 

[Redwasp]

If its soil and not pure coco coir, (or however it is spelled) with out perlite or something similar, you will be fine at first with careful watering. Can test this yourself and see. But with just soil 2 things happen. Each water slowly compacts that soil. At first nice and airy. By the time the plant is done your gonna have a block of hard dirt. Will be hard as a rock. The second reason for this is the organic material breaks down and becomes more hard non airy soil. I went back and reread and am still a bit confused as to what your using. Maybe because it 4am. Maybe for other reasons, lol. If its soil let me know and i can help with that. If its coco coir ask camp or someone else. Never used it. Grew up in the dirt, farmed the dirt growing up, know dirt, and will die playing in the dirt.

 

[Campesino]

Redwasp it's 70% soil and 30% coco. Normally this media would be more like soil than coco, and I think your advice about watering and aeration is completely appropriate. I just think the Coco may be causing problems with Ca and Mg, since it can act like a magnet and suck all the Ca and Mg out of nutrient solution if it is unbuffered.