You can attach plastic on the top of the roof and make a little lean to greenhouse against the house --- even place a light bulb or heater in there for extra heating when it's cold (safety --- make sure you use a GFCI)

Greenhouses are easy to build out of PVC / plastic - and it's great to be able to go out and work - potting plants / seeding / etc. while it's freezing outside. Two years ago I was starting seeds on Christmas day - beautful (but cold) day, birds were singing, listening to christmas music and seeding plants / transplanting --- I was enjoying the sunshine (while in the greenhouse) -- a wonderful Christmas day I will never forget.

Plastic tents for individual plants (like 'wall of water' people use for tomatoes / etc.)

cold frame --- can even use heat tape underneath for extra warmth

I was thinking more of placement etc. but all your ideas are very good..... reinbeaux ... do you think a large jar would work for small plants?????? P.S. reinbeaux you made me laugh..... lol you're hard core.... starting seeds on christmas!!!! That's almost as funny as when I start planning christmas gifts decorations etc. in august..... but then everyone calls me a hoo...... :)

A greenhouse frame made of PVC will collapse in a N.J. snowstorm. In fact, commercial metal hoop houses covered with poly can and do collapse under the weight of heavy, wet snow.

Placement huh?
Placement in the basement for winter works for some tropical-ish plants;)Karen