I think you can get one of those patio heaters without a green house. Those palms will get too big and if you ever ate outdoors in a place with those heaters, they don't need a structure. Ideally the sturcture would be better, but I don't see considering they get so tall, that it would be possible. I had some tropical that died last winter, I have a few new ones, but nothing too difficult this year. Some cannas and I am zone 10, so I have a philodendron. I have palm tree, but it looks horrible all year. I think it's a Mexican palm.

Wow, lots of questions! No problem. The palms were just small one gallon container plants that I purchased at local variety stores. They weren't even from a regular nursery. The boxes are made from 2 inch thick blueboard styrofoam used in construction, and regular pine lumber. (This year for the first time I screwed on treated fir 2x4's on the bottom of each box since regular pine rots out too easily.) I cover the boxes with clear plastic to keep the moisture off of the boxes. The palms receive no heat other than 2 to 3 screw-in flourescent light bulbs that I have attached to the top of each box with screws. I use inexpensive plastic or ceramic light fixtures. I have not worried about the ground freezing, although I used to wrap a garden hose around the base of each plant with a little water flowing through the hose since I must do this to keep my water lines from freezing, anyway. I just ran the water into a ditch. The last several years I have not wrapped the trees with the garden hoses and they do just fine without them. They either get enough heat from the light bulbs, or don't mind the frozen soil. ??? Regarding the Abyssinian (Ensete) Banana, some years I chop off the leaves, repot them in 5 gallon pots, and stick them in an unheated, unlight storage room in the basement, maybe watering them once or twice during the winter. This year I did the same, but put them in a heated room in the basement, but they get very little light. They are doing just fine. They tend to go dormant or grow very slowly. Don't overwater! Regarding grapes, there are a variety that I have purchased from several mail order nurseries that offer grapes good in zone 3 and 4. I don't remember the varieties now, but maybe I can dig out the catalogs and find out. In answer to the cannas and elephant ears, unfortunately they all must be dug in the Fall. I'm also experimenting with magnolias, azaleas, wisteria and other plants they have considered tender in the past. New varieties are being found, hybridized or developed each year that pushes the limits on cold hardiness.

I use here in my Connecticut location zone 6/7 a small plastic greenhouse that is opaque. The palms sit in a protected southern location, that receives all the possible sun, and has excellent drainage. I use no artificial heat. The lowest temperatures here the last 2 winters was about zero. I mulch with oak leaves and straw. Both palms- a Waggie, and a Fortunei receive some leaf damage, but no spear pull. Strangely enough during the winter of 06-07 the Fortunei did better, this year the opposite was true.

Yes, I'm hoping for green leaves next Spring too - and then maybe finally some progress toward bigger and better things from there. I do also have a couple water-filled plant protectors; they're like the 'wall of water' things you see over tomato plants in the Spring, only they're made of rigid plastic. I might give one of them a try when a really cold spell hits. I would leave the open-top water-filled protector over the plant during the day, then add the upside-down bucket at night for an extra layer of insulation. So far we've hit the high teens a couple times, but I'm talking about lows in the single digits before I would take this added step. If do I succeed in growing the Takil bigger, then in the next year or two, I'd really like to try putting in a buried soil heating cable along the perimeter of my 'subtropical' garden. If I ran that along the outside edge, and with the house foundation on the back side of the garden, I think I could pretty much keep the ground there from freezing all winter. As it is, it freezes intermittently during the cold spells.