Questions about seedlings:

I discovered my soil mix had too many nutrients for seedlings. I used nutrient free generic soil and have two spouts about 4" inches tall. Stems seem weak. Can someone give me specs on seedlings? I've read a lot of threads, have Jorge's book in PDF format, but can't find specific seedling info.

How long after the seed becomes a seedling do you introduce nutrients?
Also, I have a whole set-up with 400W HPS light. When are seedlings strong enough to go under this light? and when do I transplant seedlings into my "soil mix" (60% soil, 15% pearlite, 10% bldg sand, 10% worm castings, 5% fert 12-6-6).

Lastly, big thanks to ALL those who contribute on this site. Your knowledge and experience is much appreciated.

 

don't put nutes to the seedling until the cotylendon (the lil round leaf) falls off, and even then very very light amounts

You could transplant to that soil after ^ that happens.

The 400w HPS is best used for flowering, a 400w Metal Halide conversion bulb would suit you better for vegetative growth. ($50). I usually moved my seedlings under the HID lighting as soon as they had 2 leaf sets, just keep the light a lil higher so you don't burn them.

 

Can I use the 400w Metal Halide in the same unit and ballast system as the HPS bulb? Thanks for the response!

 

after more reading I see it's a "conversion bulb". I have one on the way. Thanks for the tip.