Seedlings turning yellow @ 2nd set of leaves

Hi - i have had 4 successful grows in the past (autoflowers). So the last 3 attempts have resulted in seedlings turning yellow and not growing.
I tried to duplicate what i did when successful but the seedling keep turning yellow early on.
for this attempt, I have the seedling in a solo cup with OF Happy Frog no add’l nutrients.
I added about 3-4 oz of water when initially planting the seed(PHd to 6.5)
they are about 10 inches from a 125w Hydrofarm Agrobrite CFL.
Light is on 24/7 at this point
Tent temp is always 70 - 75 degrees with RH around 40

I am mystified. Any thoughts? I have not really cleaned out the tent and components between grows - don’t know if that would matter.

Thanks in advance


Give it a few days for chlorophyll to fill in color. You shouldn’t be having nute or pH issues in fresh Happy Frog at this point.

Waterings should be measured in ml at this point, but the plant seems to be doing fine. Should be okay so long as you are letting the soil dry out between waterings. Less is better with seedlings.


Hi thanks, i also thought there should be no issue.

i don’ think that i mentioned that the first set of leaves came in at a normal healthy green but started this
yellowing effect



Yellowing in the center of the plant among new growth is usually an iron deficiency, but it shouldn’t be a problem with new soil. Give it a few days and if it doesn’t get better we can look again.


I am very new to al of this…
Just curious what kind of H2O are you using? Tap, RO, distilled?

This has happened to me using Zero Water, cleared up with tap water in a week or so…

So much fun!!

Just tap water - ph at 6.5

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Whats ur soil

Did your seedlings ever green up? I’m having the same problem with my week old seedlings in Happy Frog soil, watered with distilled and were under domes until today.

No - they never did. I had the same issue 3 or 4 times in a row. So after eliminating all potential causes (watering, lights, nutrients, ph, etc), it left only the environment. So I thoroughly cleaned and disinfected my grow space and equipment. I had done several grows without a thought of cleaning. I started a new grow and have not had recurrence of the issue. I will say, though, that your yellowing doesn’t look quite the same as mine. So hopefully yours might still be fine.

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