I usually transplant my seedlings into bigger pots before putting them out, so I suggest that you do it...but gently! I often use the handle of a spoon or something like that to ease the seedlings out of their initial pots.

Tomatoes have the ability to grow roots all along their stems, so when you transplant them, plant them good & deep, so that the leaves are just above the soil line. When I start my tomatoes early enough (which I didn't this year!) I usually transplant them a couple of times, pulling off lower leaves and transplanting them more deeply every time. Do this carefully, of course.

Unfortunately, if your seedlings are leggy, the light they're getting isn't good enough. Some people have luck starting seedlings in a sunny window, but those are usually right on the sill, up against the glass. Indoors is hard.

If you're having some warm days (even if it's only sometimes), you could start the process of hardening off your seedlings. Move them outside on a warm day, into the shade in a sheltered area. Gradually move them closer to the sun, and then right out into the sun, starting with short doses, and increasing the time until they can be in the sun all the time. This will improve the legginess, both because they'll be getting lots of light, and because the wind will cause them to build thicker, stronger stems.

Of course, bring your seedlings inside if the temps drop too low. I brought my tomatoes in last night, because the forecast said it would drop to 40 degrees (45 or warmer is best for tomatoes), but since it didn't get nearly freezing, it might have been fine.

I'd bet that your onions could go out already, since they don't mind colder temps. Make sure to introduce them to the outside work gradually, however, as explained above.

Good luck!

You might want to check out the many FAQs offered over on the Growing from Seed forum. They cover all the details for each stage of the process and you will also find discussions there including photos on how to transplant and how to prevent leggy seedlings, lighting set-ups, and much more.

Dave

Here is a link that might be useful: Growing from Seed forum

I usually transplant my tomatoes twice. I go to a grocery store and buy clear plastic disposable drinking glasses for the first transplant. Drill some small holes in the bottoms so that water can drain. I like the clear ones so I can see the roots so I can tell when they are starting to get root bound. My last transplant which will be next week goes into the large disposable beer keg plastic glasses. Same thing I drill holes in the bottom for drainage. I use miracle grow potting soil and my plants look like the fifteen dollar plants at the nursery before planting. I like the disposable plastic because the plants just slide right out and I reuse them next year to keep cost down. My biggest investment was two double four foot florescent light fixtures with four bulbs. Most windows in these parts are using low E glass so even if you get a lot of sunlight in the room not much is beneficial to the plants.

Thank you so much for all the good advice. (And the link the forum--missed that!) I'm off...

andesgrrl,

You can plant the onions directly in their final place even when they are still rather small. And yes, tomatoes can be repotted easily to larger containers before setting out.