Other than small plants being started from plugs or seedlings, my "Everything Else" GH is pretty much empty from April until November. The only plants in my "Orchid" GH are those "baby" ones, in 2" and 3" pots. Everything else will be outside, under oak trees. I am hopeful that the aluminized solar blanket over the "Orchid" GH will suffice as a shade cloth, but only time will tell. Because of the semi-transparency of the polycarbonate panels that comprise my "Orchid" GH, you couldn't see out anyway. So whether there is solar blanket material over it or not, really makes no difference. The solar blanket lets in lots of diffused light, so it is about as light in my GH's as it was without that material wrapping them. If you decide on trying this material, and now you know it comes in clear and aluminized (though both are labeled "clear", very confusing), if you go with the clear, non-aluminized type, I can promise you it will be as bright with it on as with it off. It appears to let in 100% of the available light, just like the clear polycarbonate does. If you needed a shade cloth before, you will definitely need one as before.
