Greetings,

After observing on and off for a couple of years, I decided to post a question. But before I do that, many many thanks to those who have helped me with my hobby home-attached greenhouse.

I a bit of a tropical nut and I've gone one step further this year. I need to build a temporary enclosure to protect a certain specimen by the pool. It is a Sabal palmetto. It's about 13' tall right now and planted in a 20" raised bed. I did the raised bed on purpose not only for the look, but so the enclosure would keep the top roots above freezing. I live in zone 6b which means there's no way this thing will survive without protection. I'll just run a small electric heater with thermostat to the enclosure.

Putting to use what I already know about greenhouses, the entire enclosure will be insulated except a south facing angled window made with some kind of glazing. The 2 key features to this enclosure must be the ease of set up and tear down every year, and some decent efficiency for economical reasons. My initial thoughts are this, but please feel free to criticize anything I say. I was going to make a metal frame (probably square tubing or aluminum angle) and fasten 4x8 sheets of blue 1" styrofoam for all sides except the south facing window which I was leaning towards twin wall polycarbonate for structural strength. I'll tape the seams to get as close to air tight as possible. I'll need some kind of vent for cooling, but I haven't figured out exactly what yet. The shape of the raised bed is making my structure difficult because the bed is 6'x6'. The trunk is 1' diameter, and the crown this year is only a couple of feet diameter (because that's how you buy them). Eventually, the crown diameter will be about 8-10', so I'll either have to trim off lower leaves, tie them upright, or make the enclosure 8x8 all the way up. I thought for now the bottom might be 8x8, then tapering in to 4x4 up to the top. The even numbers will be nice to not have to cut the foam. The one thing that scares me is the strength of the 1" foam. 2" would be way stronger, but also more money up front. Wrapping the tree is not an option. Winters are too long up here and I don't even want to try it.

Any help is greatly appreciated.

Stosh