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And what do you do in winter? In many mountain areas you can't grow sensitive plants unprotected even in summer...

• logfromblammo 8y ago
  Generally, you place a thermal "fruit wall" poleward of the plants you wish to protect. In winter, the wall absorbs some sunlight, and reflects some onto the plants, while re-radiating heat. The exact angle is determined by prevailing wind direction. The roots get a thick blanket of mulch. If you have enough money, you can then stretch a roll of translucent plastic film from the top of the wall and stake it out to form a lean-to. Or, a light frame can eliminate the need for stakes. (If you're really rich, you can put glass panels in the frame.) Throw a straw blanket over the transparent layer at night, and dangit, now you have a greenhouse, which we were trying to avoid doing. Building an entire field's worth of Chinese-style thermal-wall greenhouses is really cheap, relatively speaking. An unmortared wall made of interlocking compressed-earth blocks will last at least a few years. (Obviously, growing only plants that can survive the local climate without any assistance is cheapest--you just plant the seeds and wait.) Tunneling is a large capital expense. Collapse/subsidence prevention, pumping, and tunnel air management are large ongoing operating expenses. The cost to heat and cool a tunnel, on the other hand, is nearly zero. The greenhouse might need a pile of compost in it to keep it warm enough.