No, we’re not talking about that maze you need to drive through if you want to get to Logan International outside of Boston. Low tunnels are an inexpensive and ingenious way to extend your growing season.
Check out the information on these short-statured wonders provided by West Virginia Extension:
About Low Tunnels
Are you looking for a way to extend your growing season? Do you not want to invest a lot of money? Is a permanent structure not appealing? If you answered yes to any of these questions, low tunnels might be right for you!
Extending the traditional growing and marketing season should be a high priority for Northeast growers. One low-cost method of accomplishing this is to use low tunnels. Low tunnels are temporary structures that are approximately four feet tall and three to six feet wide. Hoops constructed of wire (9-gauge) or pipe (metal or plastic) can be used to support row cover spunbond fabric or polyethylene plastic to create a mini greenhouse over the crops.
Low tunnels are inexpensive, easy to construct and can fit into any size garden. These temporary, easy to move structures allow for increased crop production by utilizing season extension and overwintering of cool-season crops. Low tunnels can be used in winter and early spring to protect crops from cold injury and wind. These structures also can be used during summer with shade cloths to protect crops from insects and high temperatures.
Materials & Construction
Low tunnels can be constructed over already established crops and raised beds or before planting. Be sure to have your groundwork and tilling completed prior to installation of a low tunnel.
You can construct your own low tunnel in an afternoon with supplies purchased at your local hardware store or from a kit.
Materials that can be used in the construction of hoops are ½- or ¾-inch PVC pipes, eight feet long, and ½-inch steel rebar, 18 inches long
- How to Construct: Begin by placing the steel rebar six inches into ground at a 35º or 45º angle. If leaving rebar in the ground, make it noticeable by either painting, placing flags or using rebar caps to prevent tripping hazards. Place rebar three to four feet apart in rows parallel to one another. Using eight-foot sections of PVC pipe, place one end of the pipe over the rebar, bend the pipe and place the other end of pipe over rebar directly across, creating a hoop. Continue to place rebar and PVC every four to five feet apart in a row.
Note: PVC pipes do have a shorter lifespan than metal hoops.
Metal Hoops – Materials: 10-foot metal hoops (typically known as Quick Hoops) and a metal hoop bender
How to Construct: Metal hoops are bent into a half circle using a hoop bender to assure they are identical. Depending on the style of the metal hoop bender, different widths can be created to cover the row or rows. The hoops are placed five to six inches directly into the ground. Each hoop is spaced five feet apart in a row. A top rail of pipe connecting the bows can be added to strengthen the metal hoops.
Low Tunnel Row Covers
Agriculture floating row covers come in different grades to protect against frost, heavy freezes and pests. You will need to decide what your plan is with your low tunnel and purchase appropriate grade row covers. One major advantage of using hoops with row covers is it keeps the weight of the snowfall off your crops.
A 10- to 14-foot-wide row cover blanket is placed over the hoops and secured taut and tightly to avoid winds removing cover and snowfall crushing. Typically, the ends are tied down with stakes and string. There are row cover snaps or clips that can be constructed from PVC tubing or purchased to hold the row cover to the individual bows. At each hoop, the sides of the row cover can be secured with bricks, heavy rocks or sandbags. Consider using objects heavy enough to hold down sides but are not permanent (at least on one side), as you will need to get into the low tunnel to check and work crops. If just overwintering crops and not harvesting, you can secure the cover more permanently by burying the sides.
Most row covers, depending on grade, will provide protection down to 24º – 28º F and are water, air and light permeable. During colder temperatures, a second layer of row cover or a heavier weight row cover can be used to provide greater protection. During winter, a layer of 4 mm or 6 mm agriculture grade plastic is placed over row cover and secured to allow snow to slide off the structure. On warmer, sunny days, the plastic will need to be lifted to allow ventilation of the tunnel to avoid plants becoming overheated. Low tunnel clips can be used to secure the lifted sides to the hoops. The plastic can cause moisture build-up inside the tunnel, therefore use only as needed.
Row covers can be removed when sunny and ambient temperatures are above 55º for cool-season crops, but may need to be placed back on in the evenings and overnight when temperatures drop into the 30s.
Considerations
Most cool-season crops need a soil temperature greater than 40º for seeds to germinate and transplants to thrive. Constructing and using a low tunnel in autumn and throughout winter into spring creates the soil temperatures needed for production.
If constructing the low tunnel during winter, cover the tunnel and let it sit empty for a few weeks to allow the soil to reach the desired temperature.
Heavy snowfall can collapse a low tunnel. To prevent this, cover with a plastic sheeting, construction-grade plastic is acceptable, for snow to slide off of the hoop structure. Reinforcing with a top railing also provides strength against snow and wind.
Although unheated, low tunnels can be used to grow cool-season vegetables throughout winter. The soil inside the tunnel is much warmer than the snow-covered ground outside. Spinach and kale are cold-hardy vegetables and can be harvested throughout winter in a low tunnel. Other cool-season vegetables will need to be harvested before the coldest temperatures of winter or left to overwinter in the tunnel to get an early start in spring.
To read the full post from WVE, go to https://extension.wvu.edu/lawn-gardening-pests/gardening/gardening-101/low-tunnels-for-beginners
