Mini Tunnels for Winter Crops

Sometimes, our customers really “get” a product and take it in a new direction. Susan Pav, a gardener from Pennsylvania, took our Garden Quilt and used it to create mini-hoop houses so she could grow crops in the winter. She took photos of the set-up and tells how she did it:

A set of four tunnels in my garden.

Lifting the tunnel to check the plants.

The tied-off end of the tunnel.

My first test crop, on Dec. 29.

Sometimes, our customers really “get” a product and take it in a new direction. Susan Pav, a gardener from Pennsylvania, took our Garden Quilt and used it to create mini-hoop houses so she could grow crops in the winter. She took photos of the set-up and tells how she did it:

Susan writes:

Some of my inspiration to try harder at season extending came from The Winter Harvest Handbook by Eliot Coleman. I thought that if his large farmer’s market hoop houses were so productive during the Maine winters, I could experiment with his techniques in a garden a few USDA zones south of Maine. In addition, his book includes a guide to the best crops for succession planting and overwintering experimentation.

I created my first set of hoop houses, or tunnels, in September of 2009, using a wire cutter to cut segments from a roll of coated wire fencing (about 2×2.5″ mesh). The 36″-high roll provides a partially formed hoop shape and can be cut into segments customized for the height you want.

For my low-growing crop of greens, I use a two-hoop design — essentially a tunnel within a tunnel. The inner tunnel is made with a 28-30″ segment of fencing; the outer tunnel with a 34-36″ segment. Plants in the inner tunnel have about 8-10″ of headroom.

Why two tunnels? The gap between acts as an insulation layer, which can be supplemented with a layer of clear bubble-wrap if you grow especially tender greens or have severe winters.

The inner tunnel is covered with garden fabric and the outer tunnel is covered with clear 2-3 mil plastic. I cut the coverings to fit the wire fencing, leaving some excess at each end and sides. I attach the sides to the fencing with staples. To close off each end of the tunnel, I gather the excess and tie it at ground level, leaving a “handle” that can be anchored with an Earth Staple.

Shop for Season-Extending products.

When I first tried this technique, I used seed that I had on hand, selecting somewhat cold-friendly crops: spinach (Monnopa, Reddy, Baby’s Leaf, Emu), broccoli raab, bok choy, Swiss chard, beets (for their tops) and even some tiny garlic bulbils for garlic greens.

After sowing the seed, I water and cover the inner tunnel with the garden fabric. Garden Quilt and All-Purpose Garden Fabric all work well. Plants growing in the inner tunnel are well protected until the temperatures start dipping into the lower 30s at night. Then I place the clear plastic on the outer tunnel, remembering to check soil moisture periodically because the plastic won’t let water through.

I tried the technique again in October 2010. Spinaches planted included Emu, Baby’s Leaf and Space. Emu did especially well, growing lush with good flavor — even in February. Swiss chard planted included Bright Lights, Neon Lights, and Bull’s Blood beets for beet-tops. I’ve picked outer leaves in December, (January was quite snow-covered), February, March and April.

Initially, I thought about using traditional support hoops for the fabric, but I knew they wouldn’t support the weight of a decent winter snowfall. In addition, it would be hard to get at the crops because you’d have to disassemble the covering. With my modular framework, you can attach each tunnel to the ground with a single Earth Staple at each end. I can access the underlying planting bed by removing the Earth Staple from either end and lifting the hoop up. If the ground is frozen solid, it can be difficult to pull the staple on the outer tunnel.

When there are feet of snow covering the tunnels, I leave the crops, insulated by the snowy blanket. My tunnels have stood up to over 2 feet of snow without damage. If high winds are imminent, I supplement the outer tunnel with additional Earth Staples along the sides. Sometimes I just anchor the tunnel with a temporary weight, such as a large branch.

At Season’s End

At the end of each season, the hoops can be rinsed, untied, nested and stored, or re-used for the next garden cycle, replacing the garden fabric or plastic as needed. My tunnels have lasted for two winters so far — with the exception of one that was damaged by a curious squirrel.

This year, I have started using the same tunnels for hardening off flats of vegetable seedlings, rooted cuttings and windowbox baby greens. So far, so good!

The inner tunnel, left, and the outer tunnel.

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7 Responses to Mini Tunnels for Winter Crops

  1. Update from Susan: We picked some spinach and chard from the tunnels over Easter weekend. They are still doing well, with the exception of a section of Baby's Leaf spinach (Burpee). The spike of 80-degree weather we had last week has prompted it to bolt. Emu and Space are still behaving. To its credit, Baby's Leaf is one of the best spinach varieties I've come across so far for windowbox planting along with lettuces, under lights in a cool basement, for year-round fresh and handy salad cuttings.

  2. This is EXACTLY the sort of thing I've been trying to figure out for my own garden. Thanks for posting this!

  3. I add 1 gallon milk jugs filled with water, they warm during the day and release heat during the nights

  4. Update: Sept. 20, 2011: We checked in with Susan to see if she's doing the tunnels again this year:

    “Right now I need to make sure I have enough room for the garlic to be planted in upcoming weeks. The mini tunnels would have to be placed where my pepper plants are still producing well, so I have a little bit of time to strategize. I will probably try the spinaches and chards again, both outdoors in the tunnels, and indoors in windowboxes under lights in my unfinished basement. The basement baby greens are always a good standby-especially when I don't feel like digging my way to the outdoor tunnels.”

  5. M Chadima says:

    what brand of lights do you prefer for your basement greens? I'm going to try that this year as well, but haven't bought bulbs yet. I have an Ott Lamp, but our main fixtures are 48″ fluorescent 4-bulb lights.

  6. Susan says:

    For the “basement greens” I use a two-tier Gardener's Supply Sunlite Garden purchased in 2004. Each tier uses three 48 inch T-8 fluorescent bulbs, the height of which I adjust as needed as the plants grow. I often use the top tier for greens and the bottom for rooting cuttings or starting seedlings,with a heating mat underneath if needed. The basement is unheated but insulated, maintaining a minimum temperature of about 60-65 degrees in winter.

  7. Choppography says:

    Susan, this is absolutely brilliant! Thanks so much for sharing.

    @Nancy, I've done the water jug thing, too, but it doesn't retain heat as well as I thought. I would check with a day/night thermometer and monitor the heat retention on really cold nights following a cloudy day.

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