Sep 19, 2013
Use of protected culture is widespread in Vermont

Long, harsh winters pose particularly stark challenges for vegetable producers in the fertile Connecticut River Valley.

The weather obstacles are being met by a proliferation of greenhouses and high tunnels, which are used to extend the season for tomatoes and other crops that grow well in much of the area’s flat, stoneless, arable sandy loam landscape.

Vern Grubinger, vegetable and berry specialist with University of Vermont Extension, said high tunnels in particular have blossomed since the pioneering work of Otho Wells and others at the University of New Hampshire in the 1980s. UNH was one of the first universities to conduct research on high tunnels, making improvements in design as well as fine-tuning crop scheduling to maximize profitability.
The techniques allow farmers to extend their growing season to get maximum return for their investment by selling early and late-season crops.

“One thing we are seeing is a lot of protected culture. There are well over 1,000 greenhouses and high tunnels now in (Vermont),” Grubinger said during the North American Strawberry Growers Association (NASGA) Summer Tour, held Aug. 13-14.

“When I started, Otho Wells was beginning his pioneering work with promoting plastic-covered, low-cost structures,” Grubinger recalled.

Grubinger credited USDA’s Natural Resources Conservation Service’s (NRCS) Seasonal High Tunnel Initiative for boosting grower interest in the installation of protected culture applications. The initiative is funded through the Environmental Quality Incentives Program (EQIP), which helps agricultural producers purchase high tunnels.

“With this grant program helping farmers pay for the cost of it, just the number of tunnels they’ve funded (in Vermont) in the last three year, doubles our acreage of vegetables under cover. That’s been dramatic, with them funding more than 100 a year of these,” Grubinger said.

“Many farms I work with now are on 20 to 30 acres, and they will have up to 10 or 15 of these (high tunnels and greenhouses),” he said. “I have one operation in my town that has 20 of these structures. One of the issues will be there’s only so much flat field production that you have, and we’re continuing to use up the field capacity because people are building so many structures.”

All of the farms visited on the NASGA tour used some tunnels – but mostly greenhouses – in their operations. Several operations are organic, and many use multiple greenhouses in which they grow bedding plants and vegetables.

“In the spring we do a huge bedding plant, flower basket retail operation,” said Phil Mason, farm manager at Crossroad Farm in Post Mills, Vt.

Mason oversees the operation’s 25,000-pound production of greenhouse tomatoes.

“Vegetables are getting so competitive, you need the capital (generated by bedding plant production) upfront to sustain the business throughout the summer, because you’re not putting money in the bank until the end of August into October.”

Crossroad Farm specializes in greens and tomatoes, as well as strawberries, melons, flowers and bedding plants.

Tomato plantings

Tim Taylor, who for more than 30 years has owned the 60-acre Crossroad Farm with his wife, Janet, worked with Grubinger and UVM assistant professor of horticulture Buddy Tignor to produce a series of informational videos. They are accessible on the farm’s website, Greenhouse topics include structure, plant cycle, nutrition and pest control.

According to Taylor, the process for tomato growing in the greenhouse involves using a six-week old transplant that is put into the ground. The plant is germinated using a propagating material. With the house temperature at 75˚ F to 80˚ F, the seed tray is grown for two to four weeks before being put in a 4-inch pot for two weeks. After six weeks, the plant is placed directly in the ground, about 14 inches apart in double rows.

“In a 96-foot house with about 72 plants per row in about eight rows, there’s somewhere between 560 and 570 plants to a house,” Taylor said.

The ideal soil temperature needs to be 65˚ F to 70˚ F, and after planting a string system is used to string the plants using conventional clips. Later, as the trusses emerge, a plastic truss support is used.

The first cluster is pruned to about four blossoms, with the second one going from four to two.

“Because we want the largest fruit we can get, we do not drop and run our plants along the ground,” Taylor said. “We usually go about seven or eight trusses before moving on to another house. We will plant 10 crops of tomatoes in the course of our season, with the first one March 15 to 21, planting every two to three weeks after that to the end of June.”

One advantage of the region’s cold winters is the easier management of pests, Taylor said.

“IPM practices are limited, because there’s not been too many problems over the years,” he said. “All of the greenhouses are frozen over during the winter – getting down to 10 to 20 below every season. We will even come out occasionally and heat up the house in the middle of the winter and make pests come alive and let it get frozen again. Constant heating and freezing goes on all winter long, and as a result a lot of the pests just get driven off and killed.”

Taylor said the farm has never sprayed in any of the tomato greenhouses.

“We employ really careful cultural practices, where we just are constantly exchanging the air in the greenhouses with a lot of ventilation,” Taylor said. “While we’ve had some instances of botrytis, we’re not ever trying to get the optimum crop we can get out of that. Life sort of is a series of compromises and it’s true inside the greenhouse, too. You want to get the highest quality fruit off, but you don’t have to try and extend the season beyond what its normal growth cycle is.

“As a sustainable farm, we don’t believe that tomato production in Vermont is something that is environmentally sound, probably at all, except for the peak summer months,” Taylor said. “But if you’re going to try to extend your season you’ve got to find some compromise with the weather, so we aim to plant on March 21, around the first day of spring, when the sun has actually crossed the equator and is starting to work with us a little bit.”

Gary Pullano

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