Seedlings with Yellow Primary Leaves

I have never encountered this before. Many of my germed seeds are coming out with yellow leaves. The seedling leaves looks light green, then turns bleach white later. It severely retards growth after surviving. The cotyledons are a healthy green.

After they pop, I stick them under a T-5 CFL fixture, and I allow 10 inches of space between the bulbs and the seedlings. I run my veg cycles 24 hours, as always.

As you can see, I germ them in rockwool with pH 6.3. The blocks stay moist, but I guess I have saturated them at times. All affected seeds are from different strains and seedbanks.

Rockwool looks really moist. Maybe let it dry out a little? Try germing the same seeds in soil and see if it makes a difference. Rockwool has absolutely no nutrients in it so it could just be lacking nitrogen in the plant. Is the water from a tap or is it RO?

Nootnam said:

Rockwool looks really moist. Maybe let it dry out a little? Try germing the same seeds in soil and see if it makes a difference. Rockwool has absolutely no nutrients in it so it could just be lacking nitrogen in the plant. Is the water from a tap or is it RO?

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Thanks Noot, I was thinking along those lines as well. What threw me off was the fact that the cotyledons were healthy dark green.

You nailed it on the head bro. Only the seedlings in the rockwool displayed these signs. In Fox Farm + coco, all seedlings looked good after germing in the soil.

I got in the bad habit of drenching the cubes because I germinated these seeds on a heated seed mat. The cubes dried out fairly quickly, and I know never to allow a seed to go bone dry once it's been moisturized.

I thank you for reading, and even more so, responding! And perhaps a fellow grower will learn something too.

That is kind of odd how the cotlydons are healthy looking. Might be because when the first sprout the cotlydon is where the plants gets its initial surge of energy to grow. Glad I could be of help!!

Nootnam said:

That is kind of odd how the cotlydons are healthy looking. Might be because when the first sprout the cotlydon is where the plants gets its initial surge of energy to grow. Glad I could be of help!!

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That makes sense. It's so weird though. I've been doing this forever and never encountered this. But I am new to rockwool cubes, so the water saturation % may be too much. Those seedlings are hanging in there, but the growth is slowed amongst the others.

This reminds me that no matter how long you do this, you should never stop learning.

Rockwool should be well rinsed before use. Good luck grower

ballist said:

Rockwool should be well rinsed before use. Good luck grower

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You know, the hydro shop sold me some rockwool solution that wasn't cheap, so I thought I was going into this well-covered. The directions on the bottle said to soak wool overnight, then the cubes are ready for the seeds.

I don't remember the name of the product, but I'll look for it later. I'm in couchlock mode at the present