My hot house is TOO HOT!

How about using shade cloth to cut down on the heat? Also, some greenhouses let you roll up their sides. That's good both for hardening young plants off and to keep them from baking on hot days. Can yours do that? Roll up the sides during the day and roll them back down at night? Alternatively, can you roll up or open doors/windows and/or get some fans in there?

In my mind I am wondering why is a greenhouse needed at 80 Deg F ?
I start my fall plants out side in August, temp's are 80-95 deg F.
I start them in racks on a cart, wheel the cart in and out of the sun as needed depending on how strong it is.
When their ready I just plant them, no hardening is needed.
A constant watch on watering is needed for evaporation is high.

M Benson, Welcome to the Forum!    There other folks in your area that garden using the Square Foot Gardening method. The most active is Brainchasm. Get hold of a copy of All New Square Foot Gardening by Mel Bartholomew. It's a great way to grow veggies in the desert.

Green houses heat because the sun shines through the "clear" plastic/glass. Solarization. That's why on cool or cold days with any sun, they are hotter than the ambient temperature. Las Vegas gets even hotter than Fresno, CA (mas 112*) , and I put my green house away about a month ago. It won't come back out until first frost warning (Nov-Dec) and then only for the peppers and tomatoes that are in pots and that I want to over-winter. Also for new seedling in Feb-March for acclimatizing them to the outdoors. There are days during the winter that I have to open the door to cool it down!

Can you remove all the plastic/glass and just use the beds? All is not lost. It will be nice for winter

Shade cloth and open sides will be your best bet.  Even full sun plants can use shade in your extreme heat.  My little green house even came with its own shade cloth topper.

Kay

+1

I have a 10 x 20 pole type green house with a special UV cover system that is too hard for us to remove for the summer.  I'm planning on buying 30% shade cloth in a large size from a professional growing supply.  They sell it in 20 ft widths so I'll buy the length that will go over the top and down the sides a little bit.  

With the sides rolled up for air and the front wide open, I'm hoping it will actually be cooler in there than in my main garden (we spend almost 3 months over 100 degrees.)

If not, those garden beds will just have to rest during the summer and work for me the rest of the year.   

Okay, thought I would update this post as I just ordered my sun protection for my greenhouse.  Here's what I bought and the company I bought it from:

Tek Supply (professional farming supply company) www.teksupply.com  

I ended up buying:
https://www.teksupply.com/contractor/supplies/prod1;;pg111964_111965.html

I am having them add reinforcing tape and grommets.  It isn't cheap, but it will last a long time, protect my greenhouse cover from the sun which is my greatest issue for long term wear and my plants should be very happy with lots of light and much less heat.

The entire 13' W x 22' L cover with shipping ran just under $130.  We were finding that the materials cost at Home Depot or Lowe's wasn't much less than having it custom made for us.  

DREW helped me with this.  If you are in need of something similar, I highly recommend him to help out the number to reach him is 1-800-835-7877 x1658