When to fertilize seedlings? And legginess issues

[dforrest]

I made a bit of a late start on my seedlings. This is my first year growing my own. So now, May 3, I've got seedlings mostly with their first true leaves, some are starting on the second set. Official time to plant out in my area is May 15th.

My seedlings have come out very leggy, especially the tomatillos! One of them is so long it's fallen over and is lying down the length of the modules and is now reorienting itself to grow upward -- don't know what kind of a plant that will grow into, but suppose the bent part will get buried anyway once I plant out.

After poking around the forums a bit, I found the cold treatment method and popped the tray out of my heated, lighted germinator and stuck them on a table outside on a south-facing balcony but which gets little to no direct sunlight. It's 10°C/50°F now, forecast high today of 14°C/57°F and low tonight of 7°C/45°F. So maybe a bit colder than ideal, but OK I think. Hope they are not too shocked by the transition from their 25°C/77°F and bright light in the germinator. Due to space issues, there are some peppers in a few modules in the tray, I'm sure this is not ideal for them but they'll have to suck it up and be tough I suppose. I hope they don't stop growing, because I'm verrrry late with them.

Another issue I've noticed is that the green color of the leaves is getting lighter and yellower and I'm beginning to think they need fertilizing. And it struck me that I have no idea at all whether, when, or how much to fertilize seedlings.

I have a nice organic 10-9-7 with kelp and amino acids that's supposed to promote the growth phase of the plants... Should I just serve it up at regular strength for any old plant? More diluted? Concentrated? Not at all? Something else? I will undoubtedly mix in some Effective Microorganisms (from the local licensee of SDC).

I am trying to keep the soil just moist and honestly have only top sprayed once since planting the seeds. Since they've been under saran wrap and then in the germinator, the soil has stayed moist, even on top, and is just now seeming like it needs a watering.

Any advice much appreciated.