A book, "The earth sheltered solar greenhouse book" by Mike Oehler might give you some ideas. On a similar thread where i asked basically what you are asking, folks recommended googling "pit greenhouses" as well.

Here is a link that might be useful: thread

Thanks for your response sierraeast. I have looked at Mike Oehler's site as well as every other site I could find on the subject of solar and pit greenhouses. All of the info I can find is on GH's in a cold climate. Keeping my plants warm in the winter is not much of a problem here. It's trying to keep them from frying in the summer. That's where I feel the amount and angle of glazing may be critical. The only local greenhouses that I know of, are of a conventional type and are abandoned for the summer months. I may just have to take a guess at what will work and see what happens. Nothing ventured, nothing gained.
Don

It can get real involved, and like yourself, we are looking for answers. Some kinda design where the glazing can be moved according to the seasons, or the glazing being able to be blocked more in the warm months and opened more to the sun in the winter. I can see getting a greenhouse independent of mechanical heating/cooling being more of a design challenge than home builds and pretty involved. Keep in mind in the mining days, air shafts were desinged in below ground mining not only to keep fresh air in, but to help keep the inside temperature between 68-72 degrees. This was done on a local gold mine here where we currently live in the mojave desert by miners in the late 1800's. Non computer aided, uneducated miners who came up with ways of working with the earth without electricity or fossil fuels who lived in cabins built into the earth where they stayed quite comfortable all year round. Plants need light though and that's the difference. We are planning on the greenhouse for use when we move up to the sierra nevadas @ 4500 ft elevation. Gets pretty warm in the summer months, but keeping the greenhouse warm will be the challenge opposite of your concern. I guess we need to keep a researchin' and doing our homework. My wife and I can't get too crazy financially with the project,( I can see where it could), so hopefully some old fashioned, low cost ingenuity will kick in, like the old miners days,( except we have the internet with these cool people/forums)! I'll post some more references as we find them, books, websites, etc.

Here's a site that may be of interest to you sierra. www.susdesign.com They have several interactive design tools on there that will allow you to play with shading from overhang and louvers, etc. Just punch in the latitude and longitude of your new place in the sierra nevada. It will give you the sun angle, path, etc. for any location at any time of day and date on the calendar. I used it when working on the design for my current home and it was a huge help.
Don

Thanks for the link, Thewireman! Placement is going to be the first important step. We chose our lots according to the suns path in order to place our build to get the most out of the sun's path. This led to the leach field being in the southwest area, meaning trees had to be cut down in that area. It's the only area opened up without trees to block out the sun. Somewhere back there is what we have planned for placement of the greenhouse. Thanks again!

we have commerical hot houses in australia. Gets really hot here and what my friends do is keep the water level up in plants. we use sawdust and the base material as it is cheap and drains well. so maybe just keep them moist and watered constantly in summer via a computerised dripping system?