Heating in my Greenhouse

[emilymup]

We are going to put heating in the greenhouse as just haven't got enough room in the house!

Only thing I'm not too sure on is what temperature should I be aiming for? I plan to put the tommies, chillies, peppers, and other heat loving plants in there as I have plenty of cold frame space for those that don't like too much warmth.

Any advice would be greatly appreciated