You see, I don't know what excessively high temps mean to you... over 105º? The best way to lower excessively high temps is to not put a plant in the green house. Here in Sacramento, my tomatoes sit in full sun in 110º. They don't bloom well over 100, but they still get full sun. If you shade them, they will start reaching. They really like full sun. Tomatoes don't really need to be in a green house, unless it gets down to freezing, ie, extending the season... other than that, they are not tropicals and don't need the humidity of a greenhouse. To me, and all the years that I have grown tomatoes... from zone 5 to my current zone, I have never used a greenhouse. I could see the point in spring or fall, but a shade cloth would be like torturing the poor plant.

I've been hoping for some clarification on the pros and cons of leaving Aluminet shadecloth in place during the winter. I have read in this forum that it's best to remove it for the winter, but I've been confused by this website, which says that one of the benefits of Aluminet is it works as a thermal blanket, reflecting "invisible heat radiation" back into the greenhouse at night, helping to maintain warmer temperatures. I notice that this page does not mention either summer or winter, which has added to my confusion. I've read that Aluminet is most efficient at reducing summer heat gain when used on the outside of the greenhouse, but I have mine installed inside, hanging a few inches below the roof. (My thought was, if this works passably well for me, I won't have to battle keeping it attached to the outside during our wicked winds.) As an aside, I have in fact kept mine up all winter, but I think I must have an odd situation that would not apply to the original poster. My problem here in the desert is too much light and too much heat, even on sunny winter days; without the shadecloth I'd definately have scorching even in winter. In fact, I thought 40% would be enough for me since I grow succulents requiring bright light. I know now that in my bright and hot climate I should have ordered at least 50%. Anyway, I thought I'd mention that website link above. I don't know that Shad has read that website, but it has definately had me a bit muddled as I tried to understand the winter/summer issue with Aluminet. Sheri

Well, I have the home-attached curved eave. right now I have eye bolts at the top beam of the greenhouse. I threaded the rope through the eye-holes on the shade cloth and then secure it to the top of the greenhouse by passing the rope through the eye bolts on the top beam. Then I simply secure the shade cloth bottom w/ bricks attached to the rope. So, right now the shade cloth is resting on the greenhouse. I think that next spring I will buy pvc tubing (or some long, thin wood) and will put that the entire length of the greenhouse, where the bend is, where the shade cloth seems to rub most on the poly. The metal ribs of the greenhouse will hold the pvc above the poly. and this in turn will hold the shade cloth out above the polycarbonate. I think I will hold the shade cloth on the pvc tubing by drilling a hole in the pvc and then zip-tying the cloth on the pipe through the hole. Or maybe if I find some long, thin, wood molding I will use that. I assume the pvc pipe would be better, as it is wider and would hold the shade cloth up higher. I may decide to put pvc pipes on the top, middle and end of the shade to hold it above the entire greenhouse, although the top portion of the shade, doesn't really touch the greenhouse now. I would still have rope holding the shade cloth down but it would at least be suspended above the polycarbonate and I think this would work. My shade cloth is a little thinner than my greenhouse because my greenhouse is actually 8ft6in and the finished aluminet shades only seem to come in exact feet, so my shade is only 8 feet wide.

Hi jpt41, I have a small glasshouse with the roof covered in green 30% (approx) shade cloth, and the broms I have, which are mostly of the more sun-hardy type do very well in there. I would caution that when I moved them into the glasshouse initially some of them got scorched because I underestimated how hot and dry it could get in there really quickly, so I actually ended up having to leave the door, window and roof vents cranked open all the way open plus I took a pane of glass out at the opposite end to the door to create a little blow-through draft. They still need to be watered about twice as often as the outside plants do, particularly those in the smaller size pots, which I find can dry out in a single day sometimes. This is during southern hemisphere summer.