Greenhouses

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.

Greenhouse information

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.

Mom’s greenhouse, June 2010

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.”

Other Links:

• 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.