I was originally going to use the mylar on the roof, but didn't. The Panda plastic comes in 10ft by whatever length, so it was real easy to wrap and fold the excess over the top to create a nice shroud.

What I should have done right then is wrapped 4ft wide roll of Mylar around the inside about two feet off the floor to give extra coverage to the body of the plant.

Don't think you'll get as good a growrrom effect without the plastic. You could if you wanted just make your shroud out of 3mil or greater black plastic, and hang it over the top after you attached your Mylar to the frame, thus giving you Mylar reflectivity all the way, but with all the benefits of the plastic shroud (humidity/co2 containment).

The other reason I didn't put the Mylar up is that you have to be very careful not to wrinkle it, or you get hot spots from the crinkles that can burn your plant. So I held off on the first grow as I'd heard white is just about as reflective. This time I'll put it in, and try to be careful to get a nice tight pull -- and we'll see how she works on the next grow.
OR Freebird Reviewed by OR Freebird on . Pics of my $100 growroom Here it is ... I posted these in another thread, but thought I'd share them with everyone by making them a little easier to find. I built my growroom using 3/4" PVC and draped the frame with panda plastic (black on the outside, white on the inside. Am going to add a roll of mylar down lower to cover the bottom of the plants better. I used a half a sheet of 1/2" plywood for the floor -- I strategically placed extra PVC under the floor for extra support. The room is about 4x4x7 1/2. I grew 3 Rating: 5