Brian. I don't have much experience with this specific greenhouse but I suspect it will take something more than a small heater to keep tropicals in winter. I'm assuming you're Zone 5, but I think you'll find at night or on cloudy days the temp inside won;t be drastically different than outside. I'd also be prepared to be home when it does get sunny to manually open the vents to avoid overheating. Given our experience, I'd also say you probably won't need a humidifier.

I don't know about your climate, but where I live, even if I covered that entire little flap at the bottom with bricks, that greenhouse would still be gone the first time a good wind blew through.

You will never beable to keep it heated

I am planning to buy one of those too, but hubby said it will be blown over because it is so light. what about a smaller ones like these and strap it on to the building..?
http://www.garden4less.co.uk/4-tier-mini-greenhouse.asp

or alternatively..

http://www.elitegreenhousesuk.co.uk/acatalog/Window-GardenMini-Greenhouse.html

however, it is soooo tiny that you are only able to put in few small pots..
keeping it near a brick wall that receive good sunlight might help to increase the temperature a bit because at night the brick releases the heat it absorbed during the day. Anything that you can do to create a microclimate will be worth it. I love tropicals too..

good luck.. let us know what you decide to do.. i might need to do the same.

Hi. I bought a heavy plastic greenhouse last fall called "Flower Power" if I remember correctly. It pops up rather like a clear plastic tent (high enough to stand in). I believe it is from the same company....about 10' x 8'. Zips open. I bought if for $167 from Amazon. I will tell you, this is one of the best purchases I made in the last decade. If you manage some essential details you should have no problem.

First, I placed mine on my back deck (south facing) flush up against the kitchen window. This way the plants got fabulous light and the spot was very protected from the wind. I placed benches along the periphery (inside the house) and the pots of plants on top were all the weight I needed. (We get some serious wind in Oklahoma.) Finding a protected spot from the wind is pretty essential, I think. Tie-downs come with but I never really wanted to put them to the test and did not bother.

We had an unusually harsh winter last year in Tulsa. We got dumped with two feet of snow in February, and the public schools were closed for two weeks. I woke up one morning to find my little greenhouse buried under snow. Hauled out the shovel and the top popped back nicely. No tearing. No trouble at all. Having the eave from the house right above it helped some.

My heat source (and you will need this) was an electric heater with thermostat--pretty essential--you need that heat source to shut off automatically at a particular setting.

We had one especially cold night (minus 12 counts as bitter around here), where I was careless with my thermo setting. My ferns along the edges of the greenhouse, where they were touching the plastic, got burned by the cold. I think what I will do this coming winter (going to try to get a second year out of the house) is tie up my plants with twine so they do not touch the plastic sides.

I started all sorts of seeds last Jan 1 in my little greenhouse, and they germinated like crazy. My seeds were very happy in the arrangement.

I will never be without a greenhouse again. The hot summer sun in Tulsa is hideous to plastic, so I folded it up and stored it in my basement. It takes up virtually NO storage space when it is disassembled. I adore my little flower house and would buy one again without question. I am saving to build one out of glass and wood.

Good luck!

Those lights should not have an issue with the high humidity. I have used metal halide lighting pretty extensively in coral reef aquarium setups that were indoor, and the lights are only inches away from the water surface. The only time I have ever heard of anything happening is if water is splashed on either the glass on the bottom of the pendant or the bulb its self, in which case sometimes the glass shatters. But in a greenhouse I dont see this being an issue as long as you arent too crazy with the hose.