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
"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."