By Jeremy Walther
Photography by Kelly West
A common frustration for gardeners is lack of control. The books say it won’t happen, but we do get late-April freezes in Central Texas. We also get 13 inches of rain in one weekend, followed by months of nothing: a combination that garden pests and disease vectors live for. Hail, wind, squirrels, La Niña—nature puts on a plunder parade every year that’s especially painful for new gardeners.
After the first season or two, students of backyard gardening take one of three routes to defend against the unpredictable arsenal of nature: quit, learn to enjoy the seasonal spanking or fight back. But how does one go about fighting nature? One option is to consider packing the heat of a backyard greenhouse. Could that change everything?
“Well, it doesn’t exactly change everything,” admits horticulturist Matt Welch of Rain Harvest Gardens. “Man will never beat nature. But a backyard greenhouse can help a vegetable gardener stretch out the spring. It won’t guarantee success later in the season, but a warm greenhouse in January is a great place to get an early start on tricky warm-season crops like tomatoes and peppers.”
Welch, who has nearly two decades of experience growing plants in Texas—both as a professional nurseryman and a landscape contractor and vegetable gardener—says that “anything that can’t take much heat or cold can benefit from the added controls a greenhouse can give in late winter.”
“By far the simplest, sturdiest and easiest structure to build is the Quonset style or hoophouse,” says Welch. “For small Quonsets, PVC pipe is a cheap framing material. I usually use ¾-inch, schedule 40 PVC slipped over ½-inch rebar anchors that are pounded into the ground.”
Matt Vest is the head grower for Native Texas Nursery, one of the largest native-plant nurseries in Austin. He makes his living via greenhouses and he even carried the concept home, where he built an enormous backyard greenhouse almost entirely out of salvaged materials.
“I happened to find an old 12-foot by 20-foot greenhouse frame that somebody didn’t want anymore, and bought it for two hundred dollars,” he says. “I used six-mil plastic for the skin, which I got from work when they were done with it, about to throw it away; same for the ground cloth on the floor.”
Doors on either end of the greenhouse and the overhead fluorescent lights were salvaged from a house before it was torn down, posts from a former chain-link fence became legs for the tables inside, and 1-inch PVC pipe attached to repurposed lumber was used to build the top of the greenhouse. It might sound technical and intimidating, but Vest claims his carpentry skills are nonexistent and says that if he can do it, anyone can.
Welch is also a fan of thriftiness. “Be stingy, and don’t worry about how it looks,” he says. “More often than not, it seems people who invest hundreds or even thousands of dollars in a fancy kit, or hire a company to build a permanent structure, end up with a steamy, hot box of regret.”
For those lacking an immediate supply of used building materials, one of the best sources in town is the Habitat for Humanity ReStore in East Austin. “We always have lumber, PVC, overhead lighting, doors and windows, and will sometimes get rolls of plastic and large exhaust fans,” says ReStore’s Regene Anderson. “Most of our materials are salvaged from deconstruction projects, or donated by builders or homeowners, but we do also have some new materials at reduced prices, too.”
Vest reminds gardeners of the importance of greenhouse placement, too. “Try to position the greenhouse so that the sun will get to the majority of the structure in the winter. And know beforehand where any shadows fall throughout the day and in the different seasons. Even a thin line of shadow will limit production in the winter.”
“Drainage should also be a consideration,” he continues. “My backyard greenhouse slopes slightly to one side, so that it’s sometimes mucky on the low side. With the benefit of hindsight and observing how the greenhouses at work are all mounded slightly in the middle and plumb water away, I now know I should have given more forethought to drainage.”
“One small, easy greenhouse to build is the cold frame,” says Welch. “They are usually squared structures placed on the ground that look sort of like a box with a sloped, hinged lid. The lid and walls of the cold frame can be built with polycarbonate sheets framed in lumber, or even with old windows. Cold frames can even be built partially underground, which not only requires less building materials, but also provides the added benefit of the earth’s heat.”
Of course there’s always the option to purchase a pre-engineered greenhouse kit. “The kits we sell here are a snap to put together,” says Nancy Rock of The Natural Gardener. “In one weekend, even someone with very little construction experience and very few tools can build their own greenhouse with a professional do-it-yourself kit.”
The kits available at most garden centers are not designed for long-term use, but the trade-offs are ease of assembly and relatively low cost—usually less than $200. “The kits we sell will usually last about two to three years in the Austin heat before the plastic needs to be replaced,” says Rock. “But there are kits out there that last a lot longer. Rion Greenhouses come with a seven-year warranty, and most people who buy them love them. They’re more expensive, but they’re great kits.”
Habitat for Humanity ReStore
310 Comal St.
512-478-2165 • re-store.com