Not surprisingly, the outdoor temperature at the Running Bear Farm in West Burlington Township on Wednesday was below freezing.
But in an unheated, Quonset-style structure on the farm — which is 30 feet wide, 72 feet long and 14 ½ feet tall — there were some unusual things growing.
A fig tree. Several rows of spinach. Tulips. Herbs.
No, this was not a greenhouse.
The tree and the plants were growing inside a structure that mainly consists of a special, almost-clear plastic, which is supported by a metal and wood frame. The plastic lets in sunlight and traps heat. 
Unlike a greenhouse, the structure — which is called a “high tunnel” — does not have a heat source and usually operates without any mechanical ventilation, according to Clifford Bruszewski, co-owner of the farm.
High tunnels, which significantly extend the growing season for vegetables and herbs, have in recent years made “a big impact” on local farmers markets, said Mike Hanawalt, the district conservationist at the Natural Resources Conservation Service’s office in Wysox.
That’s because high tunnels, which have become much more common in the Bradford County area over the past five years, allow farmers to supply produce to farmers’ markets earlier in the season, and because they assist farmers in growing certain types of produce that doesn’t necessarily grow in the area, he said. 
For example, Bruszewski said that he grows okra, a food plant popular in the southern United States, and Jalapeno peppers in his high tunnel.
The increasing number of high tunnels in the area, which are cheaper to build than greenhouses, has resulted in farmers’ markets opening earlier in the season, said Tom Maloney, a horticulture educator with Penn State Extension.
The Mansfield farmer’s market now opens during the first week of April, whereas in the past, it had opened in May, and the earlier opening is at least partly due to construction of high tunnels in the area, Bruszewski said.
Bruszewski said he harvested spinach in December from his high tunnel and expects to have plenty of spinach to sell when the Mansfield farmers market opens for the season this year.
The Wellsboro farmers market now closes later in the year than it has in the past, which he said is related to the increased use of high tunnels, Bruszewski said.
Maloney said there are roughly 15 to 20 high tunnels in Bradford County, whereas five years ago, there might have been only one or two in the county.
Bruszewski said he uses his high tunnel even more in the summer than in the winter. 
In hot weather, farmers will roll up the walls of a high tunnel part-way, which provides ventilation for the crops, Maloney said.
Vegetables “grow amazingly well” in a high tunnel, because it provides a more controlled environment for raising them, Bruszewski said.
“It (a high tunnel) is a fabulous tool,” he said.
One of the main reasons that high tunnels have become more common is that the federal Natural Resources Conservation Service (NRCS) launched a grant program in 2011 that helps pay for the cost of a farmer’s first high tunnel, according to Maloney and Hanawalt. A significant number of the high tunnels in Bradford County were funded by the grant program, Maloney said.
The amount of funding that the program provides depends on the square footage of the high tunnel, but, on average, the NRCS aims to pay 75 percent of the cost of the structures, Hanawalt said.
Bruszewski said he paid $1,500 toward the $6,500 cost of his high tunnel, with the NRCS picking up the rest of tab.
Bruszewski’s high tunnel is one of the larger high tunnels that have been funded through the NRCS’ Wysox office, according to the NRCS.
One of the smaller high tunnels funded through the agency’s Wysox office, which measured 20 feet by 48 feet, cost $3,800, Hanawalt said.
The farmers in Bradford and Sullivan counties who have received the NRCS grants have all bought their high tunnels as kits and have supplied their own labor to assemble them, Hanawalt said.
Bruszewski said he and his wife constructed their high tunnel themselves.
“Any farmer worth his salt is capable of putting it up,” Bruszewski said.
Bruszewski said his high tunnel boosts the temperature in the structure significantly in the winter.
At 4:30 p.m. on March 5, for example, it was below freezing outside, but a thermometer in the Running Bear Farm’s high tunnel showed that it was 50 degrees in the structure, Bruszewski said.
Bruszewski added that it had been cloudy most of the day, and said that if it had been sunny all day, the temperature would have been at least 70 degrees.
One of the reasons why the grant program for high tunnels was established is that the government wanted to promote the purchase of locally grown food, Hanawalt said.
The funding for the grant program had been provided by the previous farm bill, he said. The new farm bill, which was signed by President Obama earlier this year, continues to provide funding for the grant program for high tunnels, Hanawalt said.
James Loewenstein can be reached at (570) 265-1633; or email: jloewenstein@thedailyreview.com