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Gardening & More: Utilizing a grow tunnel can extend the gardening season

BABY IT’S COLD OUTSIDE — This photo shows the open grow tunnel. When the tunnel is closed, the plastic tarp is folded over the opening. You can use a grow tunnel to extend the season for certain vegetable crops into fall and winter. Photo by Connie Oswald Stofko.
HAMBURG — Winter weather is definitely here. Not only have our temperatures been in the teens, we have had snow. Most of us have packed up our gardening equipment for the season.

But vegetables are still being grown outside, at a school garden here in Western New York.

A simple structure called a grow tunnel has allowed the growing season to be extended, said Caesandra Seawell, garden manager for the City Honors School garden, also known as Pelion Community Garden, in Buffalo.

That school is growing “third season crops” that can tolerate cooler temperatures. These include broccoli, kale, chard and kohlrabi. Other cool weather crops that you could try include carrots, cabbage, turnips, parsnips, beets and collard greens. You can even grow brussels sprouts in a grow tunnel, but you have to be patient: They take approximately 90 days to mature.

The plants were all seedlings in the fall, or were plants that had been growing in other beds. Even if the plants freeze and don’t make through the entire winter, they will be the first to come back, in the spring.

Seawell said that she has not had as much success with seeds. She tried sowing some spinach and beet seeds in early November, but they have not sprouted and probably died.

A grow tunnel or small hoop house is inexpensive to build. Seawell estimated that the grow tunnel probably cost less than $50.

She started with a raised bed that is 18 inches deep.

To form the frame, she used six pieces of rebar, each four feet long. Using a stake pounder, she drove four of the pieces of rebar into the corners of the bed, then drove the last two pieces along the sides, halfway between the corner pieces.

To form the arcs, she used half-inch PVC pipe, which is flexible. Larger pipe cannot be bent. She slipped the PVC pipe over the rebar, to form the arcs.

Seawell said that, if your rebar is cut at a slant, it could be difficult to slip the PVC pipe over, so cut the rebar straight across.

Keeping the covering, 6-mil plastic tarp, in place has been a challenge, because the bed is located in a windy spot. Seawell used plastic clips from the plumbing section to attach the tarp to the PVC pipe, but high winds blew the tarp off.

She nailed the tarp to the wall of the bed on two sides, sandwiching the tarp between the wall and pieces of 1-by-4 wood. She said that she wants to keep the front and one side loose, so she can access the interior to harvest the plants and water them, if she needs to.

Bricks help hold down the tarp on the side that is not nailed down, but when it got windy, the clips again blew off and the tarp opened up.

Seawell is looking for a better alternative to the plastic clips. She said that she is also considering orienting the grow tunnel differently, so the wind will not be so much of a problem, or placing the grow tunnel in a spot that is not so windy.

She also placed whole bags of leaves on the windy side of the tunnel, to act as a wind break. The leaves are in clear plastic bags (found at a curb), but she noted that, if they were in black plastic bags, they would absorb and hold in more heat, which might help keep the interior of the grow tunnel warmer.

Seawell is also going to be watching to see how the tunnel performs with snow. If we get a lot of heavy snow, she may use T-connectors to put a spine across the top and make it into more of a V-shape and less of a U-shape, so the snow slips off better. Because the tunnel not that large of a structure, this may not be a problem.

A grow tunnel is a simple structure that you can make to help extend the gardening season. Give it a try!

Connie Oswald Stofko is the publisher of, the online gardening magazine for Western New York. Email

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