Yellowing sprouts

A question from a fellow grower:

Any thoughts on what might be happening with these sprouts? They are about 3" away from 1000 lumen, 3000k LED light strip. Any help would be greatly appreciated.

Might need a touch of water but the light source is to close to the babies - no nutrients yet , use just a root stimulator in the germination/seedling stages of growth

Thanks for the quick response. I was concerned that these LEDs were the problem. I had over watered and added dry soil to soak up the excess. The lights don’t put off much heat at all. How far would you recommend? I also replaced the soil with 3:1 seeding soil/perilite. Using a dropper to add a few drops of water to avoid over watering.

I am not at all convinced the light being close has anything to do with it. I suspect you have those seedlings in a soil that has too strong of nutrients for seedlings.

Happy growing,


They started in peat pellets and I placed the pellets in a seed starting soil mixed with perlite at a 3:1 ratio. The soil is .03/.03/.03
Switched to two 100w CFL, 6500k, 1600 lumens each hung 12" up hoping to help them out.

Hers’s the support ticket

These sprouts are just about 1 week old

Strain: Purple Haze from ILGM
Indoor or Outdoor? indoor
Size of space: 4x4x79 grow tent
Soil or Hydro? started in peat pellets and put into seed starting mix .03/.03/.03 3:1 with perlite
Medium used:
PH: 7.0
EC/TDS ppm levels: na
Temperature: 75F with a small fan on low speed blowing across them
Humidity %: 70
Light system/watts? started with 1000 lumen, 3000k LED 3" away. just switched to two 100w, 6500k, 1600 lumen CFL’s 12" away. I also have 2-600watt Hydro Grow panels that, if they survive, I will be using once they’re bigger.

Hmm, if it really is seedling starter soil with such low nutrients, then too strong of nutrients is probably not the problem.

So in this case I would really think it has to be the pH, the pH really needs to be closer to 6.5 in soil. And if it really is a mostly peat mix without actual things that would make it more like soil, then the pH should even be lower, more like 6.0, or maybe even as low as 5.8, as a true soil-less mix in peat with only perlite should be more like a hydro pH at 5.8

How are you measuring or estimating your pH?


I agree with Mac on the ph but also wish to add the fan should not be directed at them but at the light until they have enough root structure to stay hydrated a fan directly aimed at even an adult plant will dry it’s leaves out in sustained periods the symptoms will look very much like light burn. Just a thought as I have made that mistake in the past.

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Good point about the fan and too much airflow on seedlings.


Ferry-Morse electronic soil tester. Moved fan so as not to blow on the plants. One thing I’m really struggling with is water. When I transferred the peat pellets to the 3" peat pots I watered until I saw it come out of the bottom. The soil was extremely wet, that’s when I took them back out, mixed a new batch of soil with perlite and water lightly with a dropper. The pellets are damp but not wet. Should I do three or four drops per day or allow the soil to become dry before adding the drops? I’ve got a quart of distilled water that I’ve treated to have a PH of 5.5

water from the bottom and simply mist tops with a spray bottle lightly
use a plate or plant tray add 1/4" of water to the bottom you actually want your roots to go down and in hunt of water let media soak up some water then remove excess 5.5 is good for now but you will want to raise it closer to 6 when you transplant again.
I use plastic beer cups cut a few holes in the bottoms for the first 2-3 weeks by then have 4 nodes if you want to simplify hold same cut full of dry soil then your plant if the plant seems really close to same weight water if not leave it :slight_smile:

Thanks Steve, Mac and Ron. Acted on all the advice. Ron, I like your watering advice. It was too dry. Ordered a new PH meter, TDS meter and moisture meter so as to have accurate readings and better information for future issues. 4 of the 5 sprouts look ok, the other is iffy with some brown spots. Hopefully with the advice I’ve gotten things will go smoother.

no problem glad to be of some help :slight_smile: