Hi, Mizshelly:
French tarragon doesn't propagate by seed, so you will definitely need to find plants or cuttings. Calandula should grow easily from seed, and seed are fairly easy to find at most nurseries or even big-box stores. Not sure you'd want to start it much earlier than next spring, though. I don't know if it would make it through a winter, even in a green house.
Lemon balm--most of us find it to be an aggressive grower. You may wish to see if someone in your area has some starts to share. I know I'd willingly dig some starts for anyone that needed them.
Unfortunately, most on-line nurseries seem to stop shipping most things this time of year. I wish you luck in finding what you need, though.
