The bottom leaves are my healthiest plant are yellow. They are about 4 weeks old and doing good, except the bottom leaves which are very small. One is almost entirely yellow. The dirt I'm using does have fertilizer built in, but I think the problem was not enough watering because this soil dries out very fast, and I'm also using perlite as well. Can under-watering cause yellow leaves? I doubt it's the soil because the other 2 plants are doing fine.
My plants did the same thing, I didnt try to fix anything, if its just the bottom leaves, I wouldnt mess with it.. if it starts spreading up to the middle, more than likely you are dealing with a nitrogen deffiecency, and no 2 plants are the same, so what one plant has enough off, the other might not. but normally the leaves will yellow and die off of the bottom after it starts getting older, just keep an eye out and if it starts to spread , then you can assume something is wrong. And if you soil is drying out really fast, if you are watering everyday or everyother day, its a good sign that your plant needs to be tranplanted.
If your soil has fertilizer in it namely a time release fertilizer, your plants are probably starting to get over-fertilized. Soil with fertilizer in it is very bad for baby seedlings. The best thing to do would be to transplant it into soil that does NOT have fertilizer in it and then add your own fertilizer later. This problem will get worse before it gets better so, do something about it now while only the bottom leaves are yellow.
^^, his seedlings are 4 weeks old, after the first week he would have had over nutrional problems if his soil was to rich. it being 4 weeks in already, and now just showing signs of yellowing, its not because there is too much fertilizer in it. And if you are just talking about the catlyds, the very first round leaves that came up with the plant, those are ok to turn yellow and they will die off eventually.
If the fertilizer is time release, I have seen that take 1-3 weeks to show itself. This also depends on what type of light it is. HID's will release it quicker. Pictures would realy be a great help.
Yea I will try and get pictures. The pots are 1/2 gallon maybe bigger so I think they should be ok for now. It's hard to find a variet of soils in Ohio during the winter. This soil was all home depot had. They are growing pretty fast, the strain is easy bud female seeds, 7-8 weeks of flowering. I'd say they are about 6" tall and very bushy so far, about 3-4 weeks since they broke the soil