I purchased a Snap & Grow Greenhouse - 6' × 8' from Sam's Club in October, 2009. I utilized an electrical drop cord and a medium sized space heater to keep the temperatures in the upper 40's to mid 60's throughout the winter months. Now, I am trying to figure out a way to lower the afternoon temperatures so that the greenhouse will not get over 95 degrees in the summer months....we had a brief heat spell here the past few days and the temperatures actually got up to about 122 degrees inside the greenhouse when it was in the lower 90's here. I have purchase an automatic vent opener but the vent being open still was not enough to keep the temps from reaching 100 degrees. I really want to put my dwarf Citrus trees in the greenhouse during the spring and summer months and part of the fall. I have also purchased an adjustable 40% shade cloth kit that lets through 60% light. I would expect this to help out with the over heating but would my trees get enough light? Thanks, Tim.

You can paint the inside of your gh with the special white paint (chalk) and add few solar fans blowing down to mix different air layers.
That's what I do.

Can you remove some panels?

Anyone know where I can get this white paint? I have added a vornado fan and a twin window fan to help with exhaust but I am just barely keeping the temperature from getting above 97 so far....and it is only 70 outside??

I just googled:

http://www.redpathaghort.com/accessories/greenhousepaintscleaners.html

Thanks! I also have a question about a digital thermometer. I am currently using an Oregon Scientific digital model and I put the sensor inside the greenhouse; however, depending on where the sensor is, I get a variety of different temperatures from within the greenhouse...Is there a better temp gauge for this?

You can use a solar-powered, automatic vent opener.
Terry

http://www.charleysgreenhouse.com/842-200-Vent-Openers.HTm

I don't want to create another topic so I will post here:

http://www.hort.uconn.edu/ipm/greenhs/bartok/htms/horizontalairflows.htm

I was a little confused on how the air should flow inside without making any cold air currents that might be unpleasant for some plants.

So ...by creating 2 windows on each end is it safe for plants to let them opened (I was thinking also to the thermal opener) or is there any way that the air should flow in a greenhouse without making any damage at all.

Reading the above link I discovered that probably it shouldn't be any problem.

Thanks