It's not just the students at Troy Howard Middle School (THMS) who are constantly surprised to learn new things as they explore the almost limitless possibilities offered by that school's now 6-year-old "Garden Project." Both figuratively and literally, the innovative learn-by-doing educational program is now breaking new ground with what's known as its "Healthy Greens Initiative."

Begun last year, this is an ongoing experiment thats demonstrating that even on sub-zero Maine winter days it's not only possible to go on gardening but to do so to a degree that's commercially viable and, most surprising of all, without spending a penny on heat.

Anyone who has ever turned aside a loose pile of trash on a winter lawn and marveled at the patch of still-green grass that's revealed might have some understanding of the principle involved. The truth is, many green plants including nutritious edible ones are not only hardy enough to survive freezing temperatures, given the chance they can go on growing straight through the winter.

At THMS, that chance comes in the form of two simple 12-by-20-foot hoop-style greenhouses. After constructing scale models last year, the students assembled the first of these from ordinary lumber, plastic electrical conduit and polyethylene for just $600. The second somewhat more substantial "hoop house" was assembled from a kit using steel tubing. It cost under $1,000 with Intervale Corp., a floor-covering manufacturer, picking up the entire cost through a grant.

The original $600 was raised by the students from proceeds of other garden program projects. These include the sale of rare heirloom seeds and of some 80 varieties of vegetables, fruits, herbs and cut and potted flowers, a lucrative harvest that last fall tipped the scales at almost 3 and a half tons.

At a time when property owners may look askance at the ever-rising cost of public education, the THMS Garden Project now pays its own way entirely. This even applies to the big 30-by-45-foot greenhouse purchased through an MBNA grant in 2001 when the program got under way. Unlike the two smaller greenhouses, this standard commercial model has supplementary heat in the form of an oil furnace. However, solar heat gain during daylight hours captured in the huge mass of growing beds inside ensures the furnace seldom comes on when the sun is shining. And an anonymous benefactor has this year picked up all costs of heating oil to maintain relatively balmy nighttime temperatures.

In the United States, Maine's Elliott Coleman of Harborside, onetime protégé of back-to-the-land visionaries Scott and Helen Nearing, has pioneered gardening in winter without supplementary heat. In Belfast, the district's middle school students are not merely following Coleman down that particular garden path, they're systematically exploring diverse possibilities involving new varieties of plants and new cultivation techniques.

Among the greens being tried out are a variety of "cut" or loose leaf lettuces, varieties of spinach and arugula. The students are also raising a mesclun mix, an Asian salad medley of greens dominated by mustard family members like the Japanese mitzuma. Another successful cold weather crop from Japan is totsoi, a non-hearting "Chinese" cabbage similar to bok choy only smaller. The Garden Project strives to purchase locally and many of its new seed requirements are met by Fedco in Waterville and Johnny's Selected Seeds in Winslow.

The greens are marketed at the Belfast Co-op and used in the middle school lunch program where they've proven perhaps surprisingly popular. With support from Wayne Enman, the district interim superintendent, plans are currently in the works to use them at the high school as well. A survey conducted by project seventh-graders found 85 percent of students at the high school wanted the greens added to the salad bar offering there.

Investigations conducted by Garden Project students tend to be a lot more sophisticated than the typical (dare one say garden-variety) schoolroom projects most people think of when they hear about 12-year-olds studying the plant world, the sunflower seeds sprouting from styrofoam cups on the windowsill.

THMS students may employ automated probes to track temperatures every 15 minutes around the clock at various spots in the soil and elsewhere in the greenhouses as well as outside. This demonstrates the effectiveness of such factors as an insulative blanket of leaves banked around the perimeters of the greenhouses or of the low polyethylene-draped hoops over portions of the plant beds inside.

They may also use a digital microscope coupled to a laptop computer to view and photograph the eggs and adult and larval forms of such pests as aphids and whiteflies commonly discovered on the undersides of leaves, this to determine what particular varieties they are. There are, for instance, at least three species of whitefly to worry about, each of which is best controlled with a different natural method. This permits the students to judge whether they should perhaps use Encarsia formosa, a tiny parasitic wasp, or sticky yellow tape traps or some sort of non-toxic spray like wintergreen oil or a soap solution. Like everything else in the garden program at THMS, all control methods are non-toxic and organic.

Microscopic examination also allows the students to monitor the success of these control methods. They are particularly alert for the mummified remains of aphids, proof the wasps have successfully done their work and a new generation of little wasps is happily munching away on the inside in preparation to carry on their parents' mission.

Something else the students may employ is a refractometer, a tool borrowed from the vineyard where farmers have long used it to determine sugar levels in the wine grapes. The students do as well with all their crops including the greens grown in the two small greenhouses. A higher sugar level in the leaves is better because it's indicative of plant health and natural resistance to pests. The refractometer may also be used to analyze plants for protein, carbohydrates in general, and specific vitamins and minerals. Further, it is used to analyze soil for mineral and nutrient levels so any deficiencies or imbalances can be adjusted accordingly.

But however sophisticated they might be, tools used in the garden program are merely regarded as tools. The staff most directly involved program co-founder Steve Tanguay, who is nominally a seventh-grade social studies teacher; Jon Thurston, district agricultural coordinator and former SAD 34 school board member; Linda Hartkopf, district health coordinator; Unity College intern Hannah Brzycki; consultant Mark Fulford, a Monroe farmer and soil expert; and consultant Anna Kessler of Searsport, a master flower gardener encourage the students to understand there is no substitute for meticulous observation and data collection, for making a thoughtful analysis of what they've observed and imagining new experiments.

One such investigation has involved tracking temperature variables in one of the hoop houses. During the first major cold snap of the season in early January, outside temperatures fell to 7 below zero Fahrenheit. Inside, however, once the sun came up

the air temperature climbed quickly and appreciably and the crop beds remained unfrozen.

Even in the early morning hours before dawn when outside temperatures had been at their lowest, the temperature in one bed given additional protection under a low cover of polyethylene stretched over hoops about 18 inches high never got colder than 20 degrees. The plants were unaffected. At that temperature, according to Thurston, growth may slow down to nothing but it doesn't kill them. Within a few hours, temperatures had risen to the point where growth could resume. Elsewhere in that particular hoop house, spinach seedlings had not only germinated under similar weather conditions but they were apparently thriving without benefit of the additional layer of trapped air afforded by the low poly cover.

At a public slideshow presentation in the school library two weeks ago attended by Enman, Assistant Supt. Bruce Mailloux, other district administrators and school board members, a dozen of Tanguay's seventh-graders compared relative nutritional merits of iceberg lettuce versus some other greens. For each variety of green, they showed the familiar pale heads on every grocer's shelves lag appreciably behind. Spinach, for instance, has almost three times as much protein by weight, five times the calcium, and more than five times the iron. In the vitamin department iceberg lettuce was at the bottom. Spinach had more than seven times as much vitamin C and 20 times the vitamin A. Leaf lettuces also proved clearly superior in every category tested.

Like all the activities within the THMS Garden Project, the Healthy Greens Initiative is proving successful at offering students opportunities and latitude to follow their interests and talents. Some students will be taking on the role of expert this spring in advising the older students at BCOPE, the district's alternative high school program, how they, too, can build a hoop greenhouse. Other youthful but now-genuine experts may be expected to participate next fall when THMS will host a New England-wide conference on school garden activities.

Our main focus is to let every kid get involved in some way, says Tanguay, who notes statistics showing that by ninth grade more than 50 percent of American students have become disengaged from school and are at serious risk of academic failure and the lifetime negative consequences that so often entails.

Tanguay notes that more than a century ago there was a revolution in primary and secondary education, one led by educators like Thomas Dewey who argued for a more hands-on approach, a more experiential way to learn. School gardens became extraordinarily popular with tens of thousands of them blossoming up around the nation. They saw what they had been doing wasn't working, Tanguay says. There were even school gardens in New York City's Central Park. Urban school gardens were especially popular, both with educators and with the students.

The trend continued through the first half of the last century, particularly in wartime when so-called victory gardens had a not unimportant role in feeding the nation. In the intervening years, however, these programs were mostly abandoned. Now, says Tanguay, they're coming back because they work and they have such positive results. Speaking from 20 years experience as a teacher and what he's witnessed over that time, he explains the reason for this in simple terms: It interests them and they end up taking such pride in what they do.