The Gandhi of greenhouses
PART I: Eager students flock to rural Pennsylvania from near and far to learn from the master of low-input season extension

By George DeVault

Editor's note: Steve Moore is no longer farming in Pennsylvania. He is currently the small farms manager of the Center for Environmental Farming Systems at North Carolina State University in Goldsboro, NC.

Posted April 6, 2004: The only way farmer Steve Moore could keep heating costs under control back in the late 1980s was to buy oil for his 2,000-gallon fuel tank on the futures market. And every 10 days he would also burn through 1,500 pounds of propane. That’s just the price you pay for doing something as unnatural as growing off-season tomatoes in the North.

While the early cash flow was nice, the high energy use and cost just didn’t jive with Moore’s lifelong commitment to practicing a sustainable lifestyle. He took the matter to what Gandhi called “the court of conscience” and decided that some major changes were in order.

Today, Moore’s two new greenhouses do not use a single drop of fossil fuel. They can’t. They don’t have furnaces. But Moore didn’t stop there. His greenhouses have:

No thermostats.

No ventilation fans.

No mechanical vents.

No roll-up sides (not on the outside, anyway; they’re on the inside).

No tractor or tiller inside.

No shade cloth in summer.

No second layer of plastic (on one greenhouse).

No inflation blower in that single-layer greenhouse. (His other house does have one inflation blower; it’s powered by the sun.)

No animal manures in compost that’s used in them.

No chemical pesticides or fertilizers applied to plants, pests or soil inside.

What Moore’s greenhouses do have is nearly year-round production of copious quantities of a wide variety of top-quality produce that commands top dollar. Simple in design and construction, yet sophisticated in management, these structures have a truly tiny environmental footprint and a huge positive economic impact on the farm. They are now, in a word, sustainable.

Maybe that’s why Moore’s rapidly growing numbers of students refer to the 53-year-old farmer as the “Gandhi of Greenhouses.” The comparison is a valid one in many respects. This one-time conventional greenhouse grower is a highly principled, patient and sometimes prayerful teacher who is quietly putting common sense and profit back into small-scale agriculture. Through the example of his daily life, Moore is clearly demonstrating that less can be more, with the sum of the parts being greater than the whole.

There is nothing inherently special about Moore’s greenhouses themselves. They are the exact same plastic-covered steel frames utilized by Pennsylvania State University’s Center for Plasticulture. At Penn State and a dozen other land-grant colleges around the country, researchers are busily tending to monocultures of traditional crops like tomatoes, cucumbers and even potatoes with field equipment inside these greenhouses, or “high tunnels,” as the scientists call them. A few not-so-traditional greenhouse crops—berries and sweet cherries—are also being tested under cover.

Frames for the greenhouses come from the same source, Ed Person, a New Hampshire farmer who has been using and building greenhouse frames for about 30 years. (Contact Ledgewood Farm, Rt. 171, Moultonboro, N.H. 03254. Phone: (603) 476-8829. E-mail:

But that’s where the similarities end. Moore and the scientific establishment are on two very different paths. While scientists cut the corners of square-peg field agriculture to fit the more circular shape of a greenhouse, Moore is developing a cropping systems based more on natural cycles and consumer demand than on existing production tools.

Rather than fighting nature, Moore works with the seasons. He plants a staggering array of cool-season crops in his greenhouses during the cooler months. Only as the weather warms does he begin easing in heat-loving crops like tomatoes, peppers and eggplant.

The results are truly impressive. Moore’s business plan for a “biointensive lettuce mini-farm,” for example, reaps a gross income of $25,000 and a net of $20,000. That’s over a nine-month season—on just one-quarter of an acre.

Moore held a two-day passive solar greenhouse workshop at his rural Pennsylvania farm in March. He planned on limiting enrollment to just 25 students. Many were turned away, yet the final total swelled to 35. License plates in the parking lot that weekend were from Pennsylvania, New Jersey, Maryland, Massachusetts, Vermont, Quebec, Virginia, Ohio, Michigan, Colorado, and California.

People just can’t seem to get enough of Steve Moore and his sustainable greenhouse management these days. “I spent almost every weekend of late February and March lecturing, here, at Michigan State, at Wilson College’s Sustainable Development Conference…” Moore says.

“I gave my first presentation on the energy of a sustaining food system at Wilson. With all my charts and spreadsheets, I was concerned people would tune me out. I was surprised at their interest, and it has spurred me on beyond my own insatiable obsession. That is all past now and it is the time to buckle down.”

After all, Moore still has a farm to run. Moore and his wife, Carol, earn their living by farming, not teaching, speaking, writing or conducting scientific research, although they do plenty of each. Moore is the farmer at Sonnewald Natural Foods in Spring Grove, a village about 8 miles southwest of York, Pa. Sonnewald (Pennsylvania-Dutch for “sunny woods”) bills itself as perhaps the oldest existing organic farm and natural food store in Pennsylvania. Its motto is: “Good health comes from the farm ... not the pharmacy.”

Moore’s next greenhouse workshop is not scheduled until September 24-25, toward the end of the busy part of the season. By the end of March, though, that workshop was already more than three-quarters filled. (Early registration costs $175 per person, single, or $160 per person for two or more people from the same family or farm. Free on-site dormitory space is limited.)

Moore simply can’t keep up with the demands on his time, so he is making plans for another round of workshops for next winter. Work is also under way on a website and a manual on how to design, build and operate a passive-solar greenhouse for year-round food production. The manual will be available for purchase by mail. (Keep checking for details.)

Why are passive solar greenhouses becoming so popular? The answer is simple: “Anyone can build one of these and have fun doing it,” Moore says. But watch out, he adds. “Greenhouses tend to have a herding instinct. The first year there is one; the second year, three; the third year, five. Design for the future, so there is room where you would want five of these.”

Future growth will help determine the size of the greenhouse frame you start out with. While some erect a 16- by 96-foot greenhouse to save money, Moore strongly advises
starting out with a wider, shorter frame, say, a 30- by 48-foot structure. “It will cost a little more, but then you can add to it. You will soon regret not having the extra width,” he says.

That makes proper site selection one of the first items in Moore’s lesson plan. “Accept as much natural energy as possible, lose as little energy as you can,” Moore advises. “Store an adequate amount, keep it simple—both mechanically and in management—and do it with a payback and minimal risk.”

The prime consideration in all of this is the path of the sun. “Hills, trees—even deciduous trees that lose their leaves—and buildings can really restrict sunlight in the winter when the sun of low on the horizon,” Moore cautions. That is why he advises carefully evaluating your site with a good sun chart such the one in Edward Mazria’s book, The Passive Solar Energy Book (Rodale, 1979). “Unless you are very attuned to the sun’s movements, you may be quite surprised at the actual changes over a year’s time,” he adds.

“Most greenhouses are oriented with the long axis north-south to avoid shading. In order to accept the most energy, greenhouses should be oriented east-west to maximize solar gain. Utilizing a gothic arch design will reduce the shading problem.” Keep in mind that true south is not the same as magnetic south, he adds. Where Moore farms in southeastern Pennsylvania, true south is seven degrees west of magnetic south. “It is better to orient a little to the east to facilitate more energy earlier in the day and warm up the greenhouse quicker,” he says.

Other essential considerations include:

Local zoning and other ordinances. In most places, high tunnels are considered temporary agricultural buildings and are exempt from building permits and property taxes.

Good drainage. It is essential. “Water has to go somewhere,” Moore says. “Once you have water in your greenhouse, you can’t get rid of it in the winter. It is absolutely critical to get water away.”

Moore recommends leveling your building site and, if necessary, even raising it to provide proper drainage. Soils can always be improved later with the addition of compost. “You can take some pretty crummy soil and make it good,” he reassures students.

Buy only a quality greenhouse frame. “The better houses have more purlins [supporting framework] for increased structural support. Buy a pre-drilled greenhouse frame. Never buy a frame that is not pre-drilled,” Moore cautions.

Timing. “Can I build a frame now (in spring) and cover in fall?” a student asks. “As long as you don’t get caught by weather in the fall. Give yourself plenty of time,” Moore answers. “And remember, you’re working with 50-foot-wide sheets of plastic. It doesn't take much wind for them to seem like they have a mind of their own.”

More about that in the next posting, when Moore details the finer points of construction and operation of the passive solar, sustainable greenhouse.

The Gandhi of greenhouses, Part II