I'm no expert but I believe warm temps are key for these plants. Once it is warm enough they will start putting out new leaves and at that point I believe you can begin with the fertilizer. (That's when I start mine) If its too cold the plants don't do much. They just kind of sit there dormant. I don't think fertilizing in cool weather will do much.

Heather, I agree with everything Jay said, and I have learned that if I ignore the purple it goes away on its own as the plants become more mature and begin receiving regular doses of direct sunlight. I tend to think it has more to do with immature vascular systems of the plants just not being able to utilize the P in the soil or in the fertilizer in the soil-less growing medium. The purple does not harm them in any way nor is it any indication that the plants will have trouble in the future. I had a handful of plants (maybe two dozen out of over 400) showing a little purpling when they were around 2 to 3 weeks of age. A few days later I began hardening them off outside with ever-increasing exposure to direct sunlight and the purpling was gone in just a few days. Once your plants are spending some time outside, I bet the purple goes away quickly, if it doesn't go away before that. Dawn

You can feed them any time after they get the second set of leaves. What you need to do now is stop watering them with the sprayer, you might be encouraging "damp off". Water from the bottom.

I am reading through the old stuff to get more knowledge. I found this question and I had the same questions when I first started too. So maybe I can help. Here's what I do. When tray 1 is full of VC - then you add tray 2 and likewise for tray 3 etc. When tray one was virtually full of VC I stopped feeding for a week (I am a once a week feeder so they went 2 weeks without food. I added tray 2 - with bedding only (week 1 of waiting). Then I fed only into tray 2 as there is food left in tray 1 - and they will live there for some time. So they don't all move up right away - but most will in about a month or two. Some will move down into the moisture collection tray - so look there when you add trays - you can dump them into the new tray with the VC they have made in that tray (there shouldn't be too much) and this starts the action going in the new tray. When I added tray 3 - I moved tray 1 to the top so I could use the VC easier - and keep the lid off occasionally - so the worms move down. So I have an "old tray" on the bottom - mostly VC some food (still being processed) and virtually no bedding. The middle tray is the feeding/working tray where I add new food and bedding once a week-ish. The top tray is my VC tray - and I pull VC from there for my garden. This saves me from dumping - and doing too much sorting. I put the VC in a pie-tin and pick trough that (and store it in the VC bin so it is picked through and ready to use) - I find I have a few cocoons - rarely any worms and a few shreds of envelope windows that didn't get composted (I toss those out and return the cocoons to the bin). This works for me (so far) as I have a small system and it is for home use only. Your results may vary.