A lot would depend on temperatures indoors and grow lights. Last year I started sweet peppers March 14th and this worked out perfect for a mid/late May planting. The eggplants and tomatoes I started about a week later and they both grew fast and were larger than optimal at planting. This is at room temperature with a T5HO grow light and sunny windowsill. When I tried before without the grow light, they grew very slowly, so I know this makes a big difference in growth rates.

This year we are way ahead of last year, and you are probably a week ahead of me for planting dates. I am going to start my peppers this weekend and the tomatoes and eggplants two weeks later, anticipating early planting this year. The tomatoes tolerate cold air and soil better than the others but grow the fastest. I already started hot peppers as they are very very slow to get started. 3 weeks after sowing 4 cells of habaneros all I have got is one set of cotyledons.

Last year I started my own tomoto, not sure the exact date. They germinated, but sat there forever. My room temp is about 65 to 68 during the day, and down to 60F at night. Plenty of light near the south windows. So I was really late last year.

I think the seed starting mix I made myself lacks nutritients, just plain peat moss and perlite. I did not feed the seedlings much.

If you are only using a window, based on my experience I would say start now.

I have not found that even a South-facing window provides as much sun as it seems to. They sit and don't grow and go out stunted.

Agree with Peter. Window light isn't an effective light source for seedlings. Even a full blown greenhouse uses supplemental lighting for seedlings. Sunlight this time of year lacks the needed spectrum and degree of intensity needed and the windows reduce it even more. Plus there aren't enough hours of sunlight. So your plants start out with 1 strike against them. A simple fluorescent shop light 1.5-2" above the plants for 16 hours a day solves that problem. Check out the FAQs about lightening on the Growing from Seed forum here.

Second, homemade seed starting mixes seldom work well. Not because of the lack of nutrients - young seedlings have all they need until after they develop a couple sets of true leaves - but because the drain poorly and the young roots rot. Buy a bag of commercial seed starting mix that are already pH balanced and made to drain well.

Eliminate those two problems and your odds of success will improve greatly.

Dave

I think, 6 - 7 weeks is a good window of time for tomatoes, from sowing seeds to taking outside for hardening off. .

I sowed mine on 2/21 and intend to take them out late March to harden them off. My seedling are growing faster now. They are in average 4" tall. I like them 8 to 10" at plant out.

With peppers I used to start two weeks before tomatoes.

Sey

PS: A little update to support what I said above:

Here is a picture of a tray after 26 days from sowing or 20 days from germinating:

In two weeks they will go out for hardening off.