Super Greenhouse
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Plastic sheeting:
The grow tunnels make it possible to extend the season by several months. Used plastic sheeting is stretched over bows of old plastic water pipe.
 

 

Grow tunnels inside the greenhouse capture still more heat

Moore is always on to new and better ways to hold more heat inside. Old greenhouse plastic is cut into long strips and draped over five permanent beds inside the greenhouse to create what Moore calls grow tunnels. Heat-holding brick walkways underlain with foam insulation separate the beds. The plastic is supported by bows of old plastic water pipe. The bows are anchored on short sections of steel reinforcing rod driven into the ground on either side of the beds.

"The grow tunnels appreciate some more heat," Moore says. "We pull the plastic back during the day. The sun warms earth, then we pull plastic back on at night."

Moore uses plastic sheeting on the outside of the greenhouse for four or five years until its ability to transmit light diminishes. Then he replaces the outer coverings and uses the old plastic for up to six more years in the grow tunnels.

In March, growth inside the greenhouse is so vibrant that the inner covers are no longer needed. Moore moves the bows and plastic on to outside beds where they are erected on metal posts lining the beds. In midsummer, many bows are covered with shade cloth, which allows Moore to produce sweet, juicy lettuce through summer. Moore grows more than 10,000 heads of lettuce for his CSA customers.

The ends of the greenhouse are framed with lumber. One end is covered with bi-walled, 8 mm polycarbonate panels. The other is draped with plastic sheeting that is held on with old drip irrigation tape and staples.

When the temperature outside dipped to -27 C last year, the thermometer read -8 C inside the greenhouse and grow tunnels. That's cold, but not cold enough to permanently damage Moore's lettuce and other cold-hardy greens.

Yields are impressive. Last year, 12 square meters of Oriental Express eggplant produced 608 fruit weighing 78 kg. That is 6.8 times the average U.S. yield. Nine square meters of Ace green peppers yielded more than 10 times the U.S. average, producing 923 peppers weighing more than 75 kg. Forty Sun Gold hybrid cherry tomato plants produced 2,500 to 4,000 juicy, sweet tomatoes each week.

"It gets really hot in our greenhouse in the summer with only natural ventilation, as you can imagine. These are tropical crops and they just love the heat," Moore says.

For pollination, Moore relies on honeybees and bumblebees from hives that he keeps nearby outside. He grows some yarrow and buckwheat inside the greenhouse to help attract beneficial insects.

"We don't spray anything in our greenhouse, not even organically approved sprays," he adds.

"We're feeding 130 households, plus 20 percent of our production by design goes to the Salvation Army for the food bank in Chambersburg."

Moore has managed to produce abundantly with far less expenditure of money and unrenewable resources. "We think small and try to leave more of the natural world alone as we scale our farms down to do a much better job with what we have."


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