I am looking to get a small greenhouse.

Most of what I'd put in there are things to overwinter. I won't need to heat much about the 40s or 50s for them, in fact at night just above freezing is sufficient.

However, if I want to start plants early as well, such as tomatoes and Cannas, that will be too cold and they'll never sprout or grow much.

My options are either - A - heat the entire greenhouse to 65+

B - find some way to warm them "locally" within the confines of the GH. Is there a way to have GH heating zones, areas of differing temperature?

C - warm the roots only (easy enough for the veggies, but for the Cannas, I'd be trying to warm a 1 gallon pot

Right now, I start veggies and my Cannas under a metal halide lamp indoors. Stays right around 70 degrees and they do great. I have read that esp. for the cannas, it's the roots that really languish in the cold.

Anyone got ideas or suggestions?