What's the temperature in the porch over the winter? If it stays above freezing that could be a viable place for them. Unless you want to get into artificial lighting. I wouldn't put them inside the greenhouse within the porch because that would reduce available light. You could put in a greenhouse heater or wrap in fleece for cold nights.

But this is only speculation since I have no experience of your climate.

If you plan of keeping them on the colder side, make sure they are planted in a very good porous mix and not to over water. Cold and damp will detroy your plants.

If it were me, I would either use an artificial light set up in the nice warm baement and grow as you would any other time of the year.

Or, I would stick that mini greenhouse right in front of the windows on your porch so that they get lots of natural light, and stick a mini heater in it for those very cold nights.

Mike

I have 2 potted Gardenia trees in the basement during the winter months. They are doing Ok under flourescent lights.