R. Wayne Mezitt is a third-generation nurseryman, Massachusetts Certified Horticulturist, and Owner of Weston Nurseries, Inc.
Wayne served as president of Massachusetts Nursery and Landscape Association (MNLA), New England Nursery Association (NENA), and American Nursery and Landscape Association (ANLA) which is based in Washington, DC.
Wayne is the horticultural consultant for GrowingWisdom.com with Dave Epstein.
Our family really enjoys growing and eating fresh vegetables and greens from our garden. In New England the “growing season” is traditionally defined as the frost-free period from May through September, depending upon where you live. People usually assume the fresh vegetable season begins when the danger of frost has passed in the spring (early May in my garden), and ends when the first frost kills the foliage on their tomatoes (around Columbus Day for us). But that’s not really accurate. There are lots of vegetable and greens that tolerate sub-freezing temperatures outdoors. And there are also more creative ways to extend your harvest, applying a bit of additional effort.
For several years now I’ve set up a 10-12 ft. long high tunnel over a section of my backyard vegetable garden for the winter. I borrowed this idea from our nursery’s 40-year success using longer high-tunnels for winter protection of our container-grown crops. The results in my vegetable garden have been quite spectacular compared to crops grown in the open garden. Not only are our fall vegetable harvests now extended, but our spring crops start producing much earlier than the garden outside.
You’ve likely seen garden catalogs offering greenhouse-like structures of varying sizes. Some of these are quite elaborate and may be more than a typical backyard gardener needs. If you are a do-it-yourselfer and enjoy trying new projects, it can be rewarding to set up a high-tunnel (or a low tunnel) with readily available components and polyethylene film from the hardware or garden supply store. Hoops are easily constructed by bending 10 ft. lengths of rigid white plastic water pipes and setting them onto iron reinforcing rods at the height you want. Edges and ends can be secured with sand bags or concrete blocks, and there are many options for entry. Many websites online help explain details – search under “garden tunnels”.
Here’s what I do. In October, choose the area to cover, set the hoops on re-rod stakes driven into the ground about 3 ft. apart and attach a conduit to connect the tops of the hoops for better rigidity. I construct an entry door at one end. After several killing frosts, I cover the hoops and ends with 3 mil. polyethylene pulled tight to prevent flapping in the wind. This year I’ve used a “wiggle-wire” mechanism to hold the poly tight, rather than rolling the edges around a 1x3” board and nailing it to the base.
When my tent covers a crop of mesclun or Asian greens planted earlier in the fall, we get greens for our table until the ground freezes hard around Christmas. By early February the sun warms the soil inside the tunnel sufficiently so certain seeds will germinate and start to grow. Spinach, arugula, cilantro, dill, lettuce, and other cold-tolerant greens have worked well for me. By the end of February I can sow radishes, peas, Swiss chard, beets and similar crops. We’re often able to start enjoying fresh greens in March.
Be aware that when the temperature outside gets below about 25° F., a single layer of polyethylene is usually not sufficient to protect new growth on tender plants like basil, tomatoes and peppers. It’s better to wait until the nights are frost free to move tender plants into your tunnel. But if you’re a risk taker, it may be sufficient to add a bit of supplemental heat (like an electric space heater) to protect those tender plants during the last frosty April nights.
I particularly look forward to digging in the soil inside my high-tunnel in February and March, as the wind and rain whip the poly above me, while the area I’m working is calm, fragrant and mild as a spring day. We still have our coldest months ahead, but it won’t be long before I’m again selecting some fresh salad greens and enjoying the promise of the new season about to begin.