Column: Seeds & Stems

In farms or backyards, hoop houses extend growing season
Marianne Rzepka

Marianne Rzepka

Tomm Becker hasn’t been afraid of a spring frost killing the lettuce, tomatoes, cilantro, kale and chard he’s growing at Sunseed Farm.

That’s because he’s growing them under the plastic cover of a 30-by-96-foot hoop house, which since last fall has been a source of vegetables through most of the winter.

Hoop houses let the sun in, and the solar-powered heat warms up the soil and keeps tender plants from freezing in early and late frosts. When a strong wind flapped the hoop house cover at Sunseed Farm last week, it blew through the openings where the plastic had been hoisted to provide ventilation. The day before had brought cold temperatures and heavy rains that flooded the nearby rye field, so the side flaps had been down to keep the heat in.

“The great thing (about hoop houses) is you can control everything,” Becker says.

Hoop houses aren’t just for farms – a backyard hoop house can give anyone a head start on the season. Then even into the winter, you can grow some cold weather crops – like lettuce – or store root crops, like carrots.

But like anything else in your garden – ponds, chickens, a compost pile – a hoop house is a project that never stops.

Small Farms, Year-Round Local Produce

The Sunseed Farm hoop house is working so well for Tomm and Trilby Becker that they’ll be getting another one in about a week at their farm off Joy Road, just northwest of Ann Arbor. In time, they want to have about five hoop houses to grow a variety of vegetables throughout most of the year for members of their CSA (community-supported agriculture) program.

The Beckers’ hoop house, along with several others in the area, were built with microloans from Repasts, Present and Future, an organization run by Lisa Gottlieb and Jeff McCabe to support local farmers. [Much of their funding comes from donations raised during their weekly breakfast salon – Friday Mornings @ SELMA – held at their home on Ann Arbor's west side and featuring local chefs and locally produced food.]

With hoop houses, says Gottlieb, a local farm can produce food for most of the year. “For our climate, hoop houses are really something terrific,” she says.

Tomm Becker in Sunseed Farm's hoop house. (Photo by the writer)

Hoop houses allow you to control, to some degree, the microclimate within the structure. When the sun is shining and the temperature is going up, you can open the vents to cool down the heat that can easily climb to more than 100 degrees, even in the winter. And when the heat increases, the humidity also builds up. After a while, the plants just can’t breathe, Tomm Becker says.

Of course, there are things that are beyond anyone’s control. During the winter, clouds and cold – along with the shorter daylight hours – will keep pretty much anything from growing. “In late December and January,” says Becker, “everything is pretty much in stasis.”

The trick is to plan ahead, planting crops late in the past season that can be picked in the dead of winter, he says.

It’s also tough to control what gets into that hoop house, which can be a warm and comfortable place for greens-eating critters – like mice and voles – during the winter. And some insects, like aphids, will find a warm, moist hoop house their idea of heaven. Moisture also is a wonderful medium for growing fungi, which is not good unless you’re raising mushrooms.

Backyard Hoop Houses

If you’re interested in simply feeding yourself and your family, you might be able to get by with a 1,500-square-foot hoop house, says John Hochstetler, who has four hoop houses that provide about 6,000 square feet of space for growing vegetables and flowers for the market. It can even be pretty cheap, he says, if you save your own seeds.

The first thing to do is figure out what you want in a hoop house. “If you don’t know what you’re doing,” says Hochstetler, “it’s going to be a big mess.”

Get some good materials, including heavy duty plastic and a framework that will stand up. Hochstetler’s first hoop house was built with plans he found online, and PVC piping from a big box store. The first heavy snowfall smashed his work flatter than a bug. Lesson learned, Hochstetler now builds his hoop houses with steel frames.

If you’d like to start with something a little smaller, Ann Arbor architect Dave Sebolt has designed a hoop house measuring roughly 12-by-12 feet that costs about $200 to build. And it’s got a shape that will keep the snow load from building up.

“The one I put together has a little roundedness on the top,” Sebolt says. “It gets into a 40-degree slope, more a parabolic arch. If the angle is 45 degrees or steeper, the snow will slide off.” (Click here to download a copy of his plans.)

He also found that snow piled around the base of the structure might cause the ribs to collapse at the ground level. His solution is to simply clear that snow away. It might also help to mulch along the base or use foam to keep out the critters.

Sebolt also suggests that hoop house builders stretch the side plastic down into the ground, to better anchor the structure against any winds that might tip it over or fly it off to Oz.

There are advantages to larger hoop houses. Smaller structures can overheat quickly. Larger ones also can overheat, but it will take longer. By the same token, larger structures will take longer to cool, which keeps frost off from the plants more effectively.

No matter what the size or the season, you’ll have to keep an eye on the temperature. Sebolt recommends using heat pistons that expand with the heat to open ventilation windows and contract when the temperature cools, so that the windows close.

The heat/cold, moisture and sun principles are the same whether you’ve got a commercial-size hoop house, a portable cold frame that fits over a single bed or something as simple as a glass bell jar or the bottom of a plastic milk carton.

I don’t have anything like a hoop house in my yard, because the space is just too small. But I might be able to use something like a cold frame, which is just a wooden box with a cover that lets in light and keeps frost away from transplants.

They can be small, portable and much cheaper than a full-fledged hoop house. You could put a 5-by-10-foot cold frame together for as little as $25 if you use recycled materials – using an old shower door for the top of the cold frame, for example. Ann Arbor’s ReUse Center or Habitat for Humanity’s ReStore are great places to look for what you need.

About the writer: Marianne Rzepka, former reporter for the Ann Arbor News and Detroit Free Press, is a Master Gardener who lives in Ann Arbor and thinks it’s fun to turn the compost pile.


  1. By Dan Ezekiel
    May 15, 2010 at 3:43 pm | permalink

    I visited this hoop house on cold days in December and February, wondering if Tomm’s claim that it could grow produce year round without any heat source other than the sun could be true. It is quite amazing to smell that garden smell of warm wet earth and growing greens on a 20 degree winter day.

  2. By Mary Morgan
    May 16, 2010 at 10:16 am | permalink

    Amy Whitesall, a writer who lives in Chelsea, keeps a blog called Yardville about her experiences building a hoop house in her backyard. [link] It’s a fun read, with some practical advice – like a description of why you shouldn’t underestimate the water pressure behind a drip irrigation system.

  3. May 16, 2010 at 5:20 pm | permalink

    Anyone with an interest in hoophouses should surely want to know Shannon Brines, who pioneered their use in this area and has been selling greens from his hoophouse at the Farmers’ Market for years. This year he started a CSA for winter greens. I’ve heard Shannon say that on the very coldest days he puts additional layers of nonwoven row cover over the plants in his house. I think that one year with an especially cold winter he did have a little bit of crop failure or at least nongrowth in February. His farm website is [link] and from there you can link to his blog, where he discusses many local food issues as well as reports on his CSA, etc.

  4. By cosmonıcan
    May 17, 2010 at 1:01 pm | permalink

    A bit off-topic, but I found a huge slime mould in the garden today, isn’t it kind of cool and early for these? May 17, Noon, looks like dog vomit type, 7X5X3/8″ bright yellow, on top of cardboard and hardwood mulch, full sun. Can’t post image, computer down.

    If it was August, I’d expect it to turn purple and start walking around later.

  5. May 17, 2010 at 4:54 pm | permalink

    That is Fuligo septica. See [link]. I like them. But I grew up with The Blob.

  6. May 19, 2010 at 12:13 pm | permalink

    Thanks for spreading the word about the value of hoop houses for Michigan farmers, schools, hospitals and other institutions, as well as home owners who want to grow their groceries year ’round. We are always looking for volunteers to support our hoop house builds. We are an all volunteer organization, and can’t do our work with out support from our community. Please contact us through our website, linked in the article, for more information and to sign up. Thank you!