by George Looby, DVM

The times are changing in almost every field of endeavor and the same for those involved in vegetable and small fruit production. With the ever-increasing demand for local produce, growers have been forced to find ways to accommodate that demand. And, with a finite length to the growing season, they have turned to high and low tunnels to help. These structures have allowed growers to continue production well after what might be considered the “normal” growing season if indeed such a thing ever existed.

The morning session was moderated by Jude Boucher, a commercial vegetable production extension specialist at UConn. The first speaker of the morning session, Steve Munno, Massaro Community Farm in Woodbridge, CT, spoke about production and rotations in movable high tunnels. Carol Grasis of the USDA, NRCS followed Steve and outlined the cost sharing programs her department has in place to assist in the construction of high tunnels. High tunnel systems may be eligible for financial assistance through the Environmental Quality Incentives Program or the Agricultural Management Assistance Program.

Making the most of your high tunnels was the topic covered by Vern Grubinger from UVM Extension. Vern started his presentation by showing some of the many types of high tunnels available and described some of the problems they are prone to. Production systems range from ventilated and unheated to the much more sophisticated units with heat and controlled ventilation.

Before undertaking the construction of a high tunnel there are several considerations that must be taken into account. Among these are the sites, the structure itself, temperature control, ventilation, soil fertility, irrigation, pest management and the costs and returns.

With a larger size tunnel, certain advantages can be realized. Taking advantage of the fact that hot air rises, high tunnels allow the hot air to vent more efficiently and avoid overheating in the warm weather. During periods of low rainfall, gutters installed on high tunnels can divert the rainwater that does fall into cisterns located at either end of the tunnel, which can be used for irrigation.

The level of sophistication regarding the heat and ventilation systems is largely dependent on the value of the crop and the projected length of the growing season. Plastic covering is used to cover plants at night and removed during the day, a bit labor intensive but quite effective. Fertilizing is done in much the same way it is done in open fields, everything is done based on soil tests, evenly distributed and mixed in well.

Roger Bartok Jr., agricultural engineer emeritus at UConn, discussed the construction of high tunnels. Zoning regulations vary greatly from town to town within the state, and many towns have right to farm regulations in place but for those that do not, construction of farm buildings can be a hassle.

The location of the structure is of utmost importance. Although not considered a permanent structure those involved should take the time to carefully consider the best possible site. Maximize its exposure to sunlight, accessibility to water and electricity, along with having good drainage. Some tunnels are designed to be movable which allows for maximizing its use when employing different cropping systems.

Managing potential snow loads is a major consideration in construction. The winter of 2011 wreaked havoc on many tunnels across the state of Connecticut. More structures have been damaged beyond repair from excessive snow loads than any other single cause. Adequate spacing between structures is essential for ease of managing snow loads as well. Additional reinforcing is an excellent investment during construction.

Ventilation is a critical factor in management. Options range from simple roll up flaps to fans regulated by temperature and humidity controls. Some growers elect to install plastic pipe beneath the soil to circulate warm water, keeping the beds at a constant temperature with the heat source.

Becky Sideman, UNH Extension, spoke about her trials using low tunnels as method of overwintering crops. The low tunnels used in these trials had bows spaced 2.5 to 5 feet apart depending on the material used resulting in tunnels 3-5 feet tall and 3.5-6 feet wide. Materials used were .5” PVC or electrical metallic tubing.

Low tunnels are best suited to crops that are planted in the fall and harvested in the spring as easy access is difficult due to their size. Wind damage is a problem and during the trials it was found that the best method of controlling damage is to bury the edges and secure the ends by wrapping and securing them to a rebar driven into the ground. Crops planted included spinach, mustard, kale, broccoli, onions and cilantro. The best results were obtained with spinach, kale and onions.

Weeds like shepherd’s purse and chickweed did well under winter conditions. Control of these weeds is best accomplished by rotating the ground used for cropping. Damage from woodchucks and voles can also be a problem.

Stone Wall Farm in Stephentown, NY operated by Dale Riggs, raises strawberries for off-season harvest. Using high tunnels she was able to market strawberries in October at a premium price. Riggs also raises raspberries using tunnels and has had good success marketing in the fall. Monitoring the nutritional status of her plants and submitting plant tissue for analysis as well as soil samples and then making the necessary adjustments based on the lab findings ensures a healthy product.

Following Riggs, Ted Blomgren of Windflower Farm in Valley Falls, NY, gave the audience a run down on how he benefits from the use of high and low tunnels in his operation. He cited protection from hail, drought, temperature extremes and pests as examples.

Caterpillar tunnels are more like low tunnels and are managed in much the same way. October through December are high management intensive months in his operation. Most of the crops are harvested by the end of the year. Spinach planted in September is harvested in February.

Justin Reid from the Cornell Vegetable Program came with some tips as to how to deal with winter pests that may affect “off-season” crops. Losses during this off-season can be higher than those suffered during the regular growing season because of the high labor and energy costs associated with their loss. The cold, damp conditions common in the late season are ideal for the development of Downey Mildew. Selecting disease resistant varieties is critical to any successful control program. Lady beetles have afforded excellent control of aphids in late season where other biocontrol measures like parasitoid wasps might fail. The Spinach Crown Mite has emerged as a pest for which there is no effective control at this time. Work is underway to come up with effective control measures for this pest.

Hard work, attention to detail, efficient record keeping and love for what they do have all contributed to the story of Pleasant Valley Farm located northeast of Saratoga Springs, NY. Paul and Sandy Arnold own and operate the farm that consists of the original farm of 60 acres purchased in 1988 and a neighbor’s farm of 120 acres that is rented.

For several years they operated as a seasonal vegetable operation use cutting edge management techniques to their system. In 2006 they started construction their first high tunnel, two more, one in 2008 and another in 2012 followed this one. Nothing was overlooked in making them as efficient as possible.

They soon came to appreciate how efficient these structures were in growing crops for year round production. For fall, winter and spring production they are growing spinach, kale, lettuce plus other cold weather vegetables. Sales at the weekly markets they attend have been impressive. They grow a number of varieties of each crop, especially salad varieties and carefully monitor all aspects of each one. At this time the winter salad mix is the most profitable.

The afternoon session ended with a farmer-to-farmer discussion of the problems common to them all and answering questions from those in the audience.