I am in Corpus so our heat will be about the same. I put on 70% shade cloth and my roof panels are 25%. A grower down at Rivera told us his shade cloth is 90% and he grows tomatoes for resale. I guess our sun and heat are very intense. I would go with a min. of 70%. Yesterday it was 93 here and my 18 x 24 greenhouse never got over 82. Before it was getting around 113 so I am very happy with the shade cloth. I'm not sure how to figure the 25% roof and an additional 70% on top. I think my shade is somewhere around 85% now and I do have tomatoes and other sun lovers inside. They all seem to be very happy including my cactus!

One thing a GH will allow you to do is alter temperatures, humidity, and light exposure. The link I have added is just a general example of an evaporative cooler. Basically, water is misted through your wall. As far as what to grow, that's not a hard question. What produce do you eat the most of...start with that. What produce is least available locally...grow that. Can you grow anything that can be stored for later use (potatoes, carrots, onions, shallots, etc...) grow that. Of course many of these are not necessarily GH candidates, but hopefully you get the idea. Then there's the germination side of things. You will be able to get heirloom seeds started earlier and in better conditions with a GH. At any rate, think first of your own consumption, then think about things you'd like to show off to friends (e.g. your very own Orchid), and if so inclined, something you could sell at a local market (I have Shiitake and Oyster mushrooms on logs, but they wouldn't do well in your outdoor environment, but could do very well in the controlled GH environment.) Good luck and have fun. Cheers, Russ Here is a link that might be useful: Evaporative Cooling Products

I visited a very established growers yard last year who's yard was entirely in shade. His gardens were beautiful....so beautiful in fact...that Exotic Angel had purchased plants from him to start new lines for them. He had 3-4 completely shaded greenhouses. His property was full of mature trees, he had no direct light whatsoever. His greenhouses were full of Hoya, lipstick plants,epiphillic cacti....just so many beautiful plants. It would I guess depend on what you are trying to grow in your greenhouse. If you felt as if you didn't have enough natural light to benefit from a greenhouse, perhaps adding supplimental light would be beneficial for you. Where there is a will...there is a way! You just have to think outside the box.

Hi Cole. After talking with several people, that have used the black poly pipes for hoops, they said they did not have problems with them getting too hot. As far as your observation on my evaporative cooling system goes, I think you are not familiar with how an evaporative cooling system works. It is strictly a pass through system. It is not like a recirculatory refrigerated cooling system where you are trying to seal a place up as tight as possible, and the same inside air is recirculated through the cooler over and over again. You must have constant air flowing in and out of a house for an evaporative cooling system to work. Here in the south everyone used to use evaporative coolers to stay cool in the summer. I used one for years myself. The way my cooling system is designed to work is basic science. The exhaust fans will exhaust the hot air which is rising to the top of the GH and this will cause a vacuum which will pull air in from any available hole. I have sealed every hole possible other then the evaporative panels, so the large majority of air will entering through them. The air that will enter through the evaporative panels will be a lot cooler then the air inside the GH and will naturally fall (hot air rises, cold air falls). This cooler air will settle along the ground of the GH keeping the plants cooler. As this air heats up it will rise to the top and be replaced by the cooler air coming in through the panels. You see, the exhaust fans will never be exhausting cool air, this defies the laws of physics. The object here is not to create a uniform temperature inside the GH from top to bottom, but only to keep the lower few feet cooler. When I say cooler, I do not mean 50 degrees here, I mean less then 100 degrees (hopefully around 90 degrees). In the end, I will end up with a temperature difference inside the GH. The upper air will be hotter then the lower air. There is no question here that there will be a temperature difference. The question is, how much of a difference it will be. Will it be 5 degrees or 30 degrees. There are too many variables involved to calculate this now, so I will just have to wait and see how it goes and report back here with the readings when I get them. Unfortunately, this will have to wait until next summer. If in the end, my system proves to be ineffective at keeping the lower part of the GH cooler, I will go back to the drawing board.