Ok a few suggestions:

First you need to get a ph tester. PH is key, and can cause many things to happen.
I would recommend getting a ph pen. It doesn't have to be one of the expensive ones. I use a Milwauke ph pen and it cost me $15 US.
Also do some searching and reading around here about ph levels and flushing. :thumbsup:

Second is I would recommend transplanting into the next larger pot size. The new soil needs to be amended with some perlite.
Marijuana likes an airy well draining soil. Mix the soil and perlite at a rate of 2 - 3 parts soil to 1 part perlite.
Again do some searching and reading about how to properly transplant. :thumbsup:

The last bit is that most people say that autoflowers perform best on a 20on/4off cycle.
And it would be better if you had one of those bulbs for each plant. (Once they have a few more nodes and are showing healthy growth.)

If you could get all this in line, I'm sure you will see better results. :jointsmile:

Here's a diagram to start your understanding of ph. :hippy:
tikiroom Reviewed by tikiroom on . Yellowing leaves on seedlings I've got a couple of seedlings (lowryder 2), at around 3 weeks or so. They have both had exactly the same treatment and are planted in Miracle Grow under CFL 18 hours a day. It is a 70watt CFL (4300 lumens) and the growing area is surrounded by a reflective mat with some yeast also bubbling away in there. I water them sparingly and have not added any nutrients. However on one of them the leaves have started to look quite yellow! The problem is not nearly as noticeable on the other plant, Rating: 5