 Get a piece that's six or seven feet long, roll it into a cone to put over the top of the tree instead of having to buy the whole roll. If you have to buy a whole roll of stuff, it's pretty pricey. It costs you a couple hundred dollars, but just buying one piece of it would be nothing. It would do fine in the full sun outside even as a very small plant. No problem at all. Okay, the concrete won't attract more heat? No.