Cool Crops
At the first sign of frost, many gardeners hang up their trowels, trading their gardening gloves for mittens.
But while most retire to indoor pursuits, a few continue the harvest.
“I've seen peas 4 inches high just sticking out of 3 inches of snow,” said Joe Horst, 69. “Snow is a great insulator.”Peas are among a handful of crops that thrive in cooler soil, but Horst and his wife Alma opt to raise spinach all year in their Adams Township garden.The Horsts begin planting the spinach in late October in two 6-by-6-foot beds.Using treated deck lumber, Horst created 6- or 8-inch raised beds, where spinach plants are covered with clear 10 mm plastic.
Horst positions a few tomato cages around the plots to prop up the plastic, protecting the spinach from the weight of heavy snows.Since the plastic traps moisture in his spinach bed, Horst can avoid frequent watering, protecting the plants from a potential flash freeze if uncovered during frigid weather.The Horsts harvest much of their crop by late March, when they use the covered beds to plant more spinach along with lettuce and onions.“We eat spinach off and on all winter depending on when the temperature gets above freezing,” he said, noting he tries to keep the bed covered in those conditions.When temperatures drop into the single digits, Horst said the plants suffer, but they rebound as temperatures rise.“We've been doing this now for about five or six winters,” Horst said.“As cold as it was last winter and so far this year, the spinach has never frozen.”
Bob and Berenice Madjaric never envisioned an all-year garden, but in 2008 they tried few things in their homemade greenhouse in Muddy Creek Township.“A friend suggested I grow a winter crop using the principles outlined in Eliot Coleman's book “Four Season Harvest,” said Bob, 73.“I originally had very little confidence in this principle and therefore put minimal effort into the project,” he said.“To my amazement, we had fresh greens all winter long.”Over time, the Madjarics fine-tuned their growing techniques, which now produce a full assortment of winter produce.Carrots, celery, beets, onions, radishes and a wide variety of greens are among the crops the couple maintains in the 30- by 40-foot greenhouse, made using metal hoops covered with a single layer of plastic.Although the greenhouse operates without supplemental heat or light, Bob, a retired engineer, constructed the house on top of 100 tons of rubble.Initially, the couple didn't capitalize on the rubble's thermal potential, but eventually Bob constructed a venting system that sends greenhouse air through the underlying rocks.Instead of using a fan to blow the hot greenhouse air outdoors in summer, Bob circulates it through the rocks, which are kept cool by the earth's insulation.
In winter months, the air likewise warms by about 5 degrees as it travels through the underground rubble.By constructing a plastic tent over the air return, the Madjarics can manipulate the temperature to help grow crops less suited to the season.Additional plastic tents inside the greenhouse also further insulate crops, which the couple says can handle temperatures of 28 degrees inside the greenhouse.When temperatures drop below that, some of the leafy tops are damaged.But roots usually remain intact, and most of the plants recover.Last winter, Berenice recalls temperatures falling below zero, causing the celery to flop and become translucent.“I thought they had all died,” she said. “But lo and behold they pulled up again.”Although plants can be sustained in winter months without supplemental light, seedlings require long summer days to reach maturity.“You have to have the plant about 80 percent of its full size by Nov. 10,” Bob advised, explaining young plants require 10 hours of sunlight a day to grow. Once established, many types of garden plants will survive with less light, growing just enough to keep gardeners with food until the spring.According to Chris Reed, gardener at the Macoskey Center for Sustainable Systems at Slippery Rock University, those rules only apply to plants that naturally thrive in cool soil. Plants requiring warmer soil — often fruiting plants like tomatoes — cannot grow in winter without supplemental heat and light.
Although light is always essential, gardening can still occur without a greenhouse or garden.Jack Book, 71, of Penn Township produces leaf lettuce under grow lights in his garage.Instead of growing in soil, Book uses a small hydroponic system to provide water and nutrients to the plants, which are anchored with a special growing medium inside coffee cans or other recycled food containers.Book also uses a special 4-foot long tent to conserve light as well as heat, since the garage itself isn't heated. A pump, much like those used in fish tanks, delivers the nutrient solution to plant roots through tubing.“In three weeks I can be eating lettuce,” Book said, noting his crop never gets bitter since he can control the nutrients and heat more than he can with outdoor crops.Jeff Dorrier, 32, who owns the Western Pennsylvania Innovative Gardening supply store in Middlesex Township, said hydroponic crops also need to be oxygenated, also much like a fishtank would.
Several specialty growing stores exist in Butler County, and Dorrier said hydroponic supplies and setups can range from large, elaborately designed systems to all-inclusive $80 planters with everything needed to grow a tomato plant.Tents like that used by Book can be zipped closed, with a reflective lining to maximize light.Although special high wattage fluorescent lights can suffice for plants in a vegetative state, Dorrier suggests high intensity discharge lights for plants that produce fruit.Lights can be controlled manually or set to a timer, with duration depending on the plant and its stage of growth.Although Dorrier likened the cost of hydroponic nutrients to the costs for conventional fertilizers, neither he nor Book had calculated utility costs for indoor growing.“A lot of people are not doing this to save money,” Dorrier said.“They're doing it because it's something they enjoy.“I like to watch something growing from nothing to a big, beautiful plant.”
