Yesterday I spent the morning building a little moveable row cover. It's tiny—44 inches wide by maybe 60 inches long, but it'll be enough to house our lettuce starts come February. By the time they get big enough to be crowded, we'll be able to pull the cover off and transplant them into rows. In a climate like ours, it's all about getting a jump start.
My friend Lucas Dinwiddie is working to do this on a much bigger scale. Last spring he got a Matching Enterprise Grant for Agriculture, or what the state calls a "MEGA" grant. The idea is to help beginning farm businesses in Massachusetts with start up or expansion costs. In Lucas's case, the grant helped him build what you see up there—a 25 by 12 foot mobile greenhouse that slides back and forth over a 50 foot plot.
The idea comes from Eliot Coleman. He's the one growing greens and root vegetables and lemons year round in Maine, and he and his wife Barbara Damarosch have written quite a few books and articles on four season farming. The idea with the moveable greenhouse is that different crops need insulation at different times of the year.
For instance, if you had a three plot system, the rotation might go something like this. You cover winter greens in Field A from late November through mid March. Then in early April, once the weather has warmed up enough that the greens will be fine without covering, you slide the hoophouse down the tracks 25 feet to Field B and get a jumpstart on your tomato crop by planting the seeds in the ground under the plastic. Once the frost free date comes, you slide the hoophouse another 25 feet to Field C where you plant seedlings of a heat-loving crop like peppers or melons. You leave the hoophouse over them for the summer, then cover another crop of greens come fall. It's a pretty ingenious system.
There are all sorts of different combinations of crop rotations you can do, and you can put as many beds in a row as you want as long as you have a long row of level space. Eliot Coleman lays out one plan that has five fields! Lucas's has a two plot system, and his plan is to cover greens in the cool months and tomatoes in the summer.
Beyond the two-for-one aspect—Lucas has essentially gained two greenhouse spaces for the price of one, which is pretty cool—the mobile greenhouse also helps combat common soil problems that arise in continually covered spaces. Pests, diseases, excess nutrient salts, and dry soil are all more common in stationary greenhouses, but are much less problematic in fields that are covered only part of the year.
If you're interested in building something similar, check out these online plans from Eliot Coleman. And if you're interested in doing something on a smaller scale, I'll post a photo and plans for my moveable row cover soon. Hard to believe, but it's time to start thinking about planting again soon. Happy dreaming!