Best Greenhouse when you can't dig in?

Zach,

Since I have been considering a venture in commercial nursery ownership/creation, I have been thinking a lot about matters of greenhouses and related matters. The limitations of the city I am currently living in made me realize that there may be a lot of people who want to improve their land, but can't do it thanks to ordinances that are meant to 'protect the land' and 'keep the city beautiful'. When faced with these challenges, but not wanting to do a run of the mill row-house, is there any sort of greenhouse design you recommend as being more in harmony with nature overall? Dome structures come to mind since you can ventilate them without electricity rather easily, though they still tend to be mostly plastic.

While I mean this question to be more on general terms that might apply to anyone, my own situation is a zone 9 area in the lowest point of Texas. Sandy soil overall with a high water table and low precipitation on average. Winds tend to be a pretty standard factor, often strong and steady. I am almost inclined not to bother with a greenhouse structure at all except that I am wanting to show how someone can transition from the standard plant production into a more sustainable one and wanted to have several 'phases' so that people who aren't ready to jump in feet first would still have a chance to learn new ideas and expand their understandings. Already I am thinking of setting up a living shade area instead of the standard shade-cloth for an outdoor sales area and if anyone would have useful insights for the 'greenhouse' aspect, it would certainly be yourself! I haven't had a chance to read over every one of your other comments to the questions of others, so if this treads on existing ground already, I apologize.

I love the idea for your living shade structure, that sounds like an excellent strategy for your climate. You can probably use glass in your case as well (so long as you don't get hail). Often you can find old glasshouses that are no longer being used and offer to take them down for the person. This results in a really nice long lasting greenhouse if you have the time to put into it.

I am not a big fan of the dome, in my experience greenhouses are most benificial at higher and lower latitudes. For these locations the dome is not the ideal glazing structure as the sun is always coming from the south (when in the northern hemisphere). I prefer all of the glazing to face south, northern facing glazing is a big heat sink, as glazings by nature are not very insulative and in northern latitudes the sun never comes from the north.

That being said with an Earth Powered Greenhouse (dug into the ground) you could grow tropicals without any energy, because you are fortunate to most likely get enough winter daylight hours. For your climate the earth temperature would be even more beneficial in the summer (providing cooling) than in the winter (when it provides heat). With all south facing glazing this also provides a strong thermosiphon at the ridge of the greenhouse. This is the pump that drives the passive ventilation system. The hot air rises, expands the venting arms and leaves the greenhouse. The resulting negative pressure draws outside air through the ground (via earthtubes) and then into the greenhouse, providing passive cooling and dehumidification. In my experience dome structures are tricky to vent, as only so many panels at the top can be vents.