The “new” 16’x28′ greenhouse (2008) in early spring of 2010. Note the roll-up side on the left. These raised beds are mostly filled with salad-y stuff, but kales, cabbages, leeks and garlic are also visible.
I am a year-round vegetable gardener but I could not do it without my greenhouses. I have two sixteen-foot wide structures (high tunnels, hoop houses, polytunnels, etc.), one that is 20′ long and one that is 28′ long. They are easy to erect with minimal skills; you could assemble one over a weekend if you had help. I purchased mine as kits (plastic, hoops, plastic hold-downs, bracing, etc.) but I supplied the lumber for the base frame and the end walls. I also made the doors, but you could easily use a wood-framed screen door. All in all, the larger greenhouse was about $1,000 and the smaller one $850. If I amortized about how many $5 bags of organic salad I have pulled out of them (not to mention heirloom tomatoes or any other thing I grow within them in a calendar year), they easily paid for themselves within one year.
The plastic is UV-stabilized commercial greenhouse grade stuff that lasts six years. Recovering one of them will cost about $200.
I have a roll-up side to allow for ventilation in the in-between seasons (spring and fall). In the high summer, I take the plastic off of the door sections on both greenhouses. Because I have often-errant chickens and I hate tomato hornworm moths, any open space is covered with screen (in most instances, deer netting with 3/4″ square holes).
No, I do not heat the greenhouses. They do quite fine on their own in the winter. I grow frost-tolerant plants in there (lettuces, mache, claytonia, arugula; all onion-family plants (though chives do a swan dive); escarole and endive; the cabbage family; and many root crops (carrots, beets, parsnips, turnips, and the like)). I grow all my garlic in the greenhouses. I cover the beds with agricultural cloth (Reemay) that allows light and keeps things a touch warmer than not. On a sunny day, they can get quite warm (80 degrees F or so) but mostly they’re simply 20 degrees warmer than the world outside. In my Zone 6B garden, twenty lousy degrees is quite a difference.
And in summer, the solanaceae crops do quite well in there (tomatoes, peppers, eggplant, etc.; also heat-loving okra, asparagus, cardoon love life indoors). Summer is likewise the only time I tend to have to water the beds. There is usually a one or two-week period in high summer that it is REALLY hot, and the plants don’t set flowers. If I lived somewhere warmer, this would be a problem and I would invest in shade cloth. As it is, I appreciate the break.
I also built a greenhouse for my mom in the spring of 2010. It’s a small (10’x12′) kit from Growers’ Solution where I also got mine, see the links below.
Here is a link to all the posts that I have tagged called “greenhouses.”
- I got my greenhouses as complete kits from Growers’ Solution, which makes their own frames.
- Four-Season Harvest by Eliot Coleman. Not just greenhouses, a must-have book!
- The Winter Harvest Handbook by Eliot Coleman. More information! Great for small farmers but good for backyard growers too.
- Intrepid slug-squisher Andy McGee has recently published The Polytunnel Handbook. (Polytunnel=hoop house=greenhouse)
- There are lots of other ways to have your own greenhouse. Google “Hoop House” and watch the results turn in. Here’s a decent site though to build one out of PVC.
- Johnny’s Selected Seeds sells tools to bend your own conduit or chain-link fence parts to make your own greenhouse.
- Eliot Coleman also has a demo on MOFGA (Maine Organic Farmers and Gardeners Assoc.) on how to build a low tunnel (a short greenhouse) to help season extension.