Can you share your location ?

Can you post a few pictures of the plants ?

It can be very difficult to do this time of year when there are such extremes in temps to deal with. That isn't usually a problem in the spring when all you have to worry about is cooler temps and getting them used to the sun. So I wouldn't count on learning much about the process from this time.

But in general I find it takes about a week - assuming the weather cooperates - longer if it doesn't. The root development is what is crucial to their ability to adapt, not the top growth, so slowing top growth when possible to allow for really good root development is vital.

These may still adapt with extra water and some shading if possible. Good luck.

Dave

Thanks to those who have commented on my problem. I have a good deal of experience with starting cuttings and seedlings in early spring and hardening off without much trouble , but have not had experience with trying to start seedling at this time of year. I agree with the statement "root development being the most importtant thing.' When time is not a factor root development will come. The only way I know to maybe slow top growth is by pinching growth tips which will also cause more branching. . In the spring I wont be fighting against all these extremes for sure, but it is a bit of learning experience to translate to next spring for tomato seedlings. I have a lot of experience with fower plants not so much with tomatoes.

The common way to slow top growth in tomatoes is to grow them in a low ambient temp environment once first set of true leaves develop - 50-55 degrees for 3-4 days then keep them in a max of 60-65 degrees. Easy to do in the spring. Not so easy this time of year. :)

Dave