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A Greener Greenhouse
Cathy and Dave Odum built themselves an eco-greenhouse in Central Point
December 31, 2009
Story and Photography By Althea Godfrey
Cathy and Dave Odum love plants, and a converted pasture in Central Point has given them lots of opportunity to indulge in their passion.
A featureless landscape when they moved in has been transformed with mounded gardens, a pond and a waterfall. But that beautiful garden is a story for another time. Now, in the middle of winter, the centerpiece of the property is the new greenhouse.
No ordinary greenhouse, this one is heated "organically," using shredded leaves and clippings. Heating a greenhouse with a compost pile is an idea that brewed in Dave's mind for a long time. Owners of Blue Jay Landscaping in Central Point, he and Kathy have always had a garden and composted the materials from it and the landscaping business.
"Knowing how hot it gets, I wondered about how it could heat a greenhouse," he says.
The experiment started last year when they purchased a kit for an 8-by-14-foot greenhouse from Halls Greenhouses. Dave's only complaint is the difficulty of putting the rubber seals around the window panels. But once assembled, the similarity with other backyard buildings ended.
Dave built a cinder-block foundation for the building about 2 1/2 feet above the ground. He filled the center with red cinder rocks. About 4 feet away from the foundation, he constructed an equally high rock wall. Into this void he laid a 4-inch pipe to circulate warm air and piled shredded leaves, yard trimmings and grass about 4 feet high above it. The trough he's created is wide enough for his small tractor to get into when the composting process is finished.
That's a good thing. The premixed material breaks down over the winter and yields an impressive pile of soft, organic compost.
"It's a lot like potting soil," says Dave. In fact, they use it for their potted plants. It's also a seed-starting mix, and almost all of their vegetables are started from seeds, along with the flowers they grew last summer for their daughter's wedding. But most of the compost is incorporated into the garden, and the dinner table reaps long-term benefits.
"Lettuce and carrots grow well there all winter," Dave says. Cathy enjoys winter snacks of snap peas when she works outside. Her favorite thing is that the greenhouse gives her a place for her citrus plants. The Meyer lemon tree is loaded with fruit, as is the lime tree. Unlike many people who bring their citrus outside during the summer, Cathy covers the greenhouse with 60-percent shade cloth and opens the doors to create airflow. The citrus stays put.
Right now, heated air is circulated by an electric fan inside the greenhouse, but that may change as Dave keeps tinkering.
"He's always trying different ways of doing things," says Cathy. For example, he swapped out the plastic pipe for a metal pipe, which seems to conduct heat better.
"The air coming out of the pipe is always between 90 and 110 degrees," says Dave. "It keeps the greenhouse at least 10 to 15 degrees warmer than outside."
That's comparable to the electric-powered greenhouses without adding to our atmospheric burden. But he's ambitious. "I'd like to keep it consistently 60 degrees," he says.
A set of metal racks holds about 100 square feet of plant starts and pots. Two raised beds inside the greenhouse hold tomatoes now. The citrus, datura, scented geraniums and other ornamentals are in pots, both on the ground and hanging. They're starting grasses and groundcover, along with a few pots of "blue star" juniper and oleander. The first of February will see them planting tomato seeds.
"They're always nice, big plants when we put them out in the spring," says Cathy.
Everything else is started in March: lettuce, cucumber and squashes. Onions are now grown from seed.
"It's so easy," says Dave.
"I'm a big pepper fan," says Cathy. "I grow all sorts of peppers."
The only complaint? The greenhouse could be bigger, Dave says ruefully.
"If it was twice that size, it'd be pretty good for us."
I have never thought that this could be a way of heating your greenhouse 