Who doesn’t love tunnels? Here’s why vegetable fans may look to them in the autumn
With cooler weather looming and frosts on the not-so-distant horizon, vegetable gardeners may soon be looking into a standard method of extending the growing season: the use of low tunnels.
These typically consist of floating row cover cloth or polyethylene film, and wires or tubing fashioned into low hoops. Using them provides a means for gardeners to keep frost off plants and insulate the soil and air within the covers. This will help stretch a garden’s growing season for several weeks until a hard ground freeze finally occurs. Material selection of the covers will depend on what a gardener aims to achieve. The two types of material offer different levels of protection.
Row cover cloth is intended for less intense weather and temperature conditions, preventing damage from light frosts with up to 4 degrees of temperature protection past freezing. As this material is both lightweight and breathable, moisture and light can still readily filter through it. This allows many of your more tender fall crops — such as lettuce, spinach and root vegetables — enough leeway to continue prospering into late fall without entirely cutting them off from the elements.
The polyethylene film option offers protection to plants far beyond a light frost. An effective insulator, this material creates a mini greenhouse for the plant life it supports. Though not fool-proof, this cover provides up to 8 degrees of protection for plants past freezing, making it practical to protect warm-season fruiting vegetables, such as tomatoes or peppers, that have managed to carry over to the end of the season.
In either of these scenarios, it is important to note that this protection does not last forever in the Kansas City area. The plants within them will eventually succumb to the bitter winter cold we endure, particularly from late December through February. Even when using heavy-duty protection, the greenhouse effect will only be able to go so far as the physical air temperatures surrounding the low tunnels create rapid freeze-thaw scenarios. The air temperature within the tunnels will still fluctuate, and eventually lead to the plants’ decline.
Even so, low tunnels have much to offer for the time they can be used. Remember that securing covers will be critical to the success of the insulation provided. You can achieve this by simply pinning down the covering with sandbags, bricks, rocks, boards, or other weights.
Landscaping staples are not recommended, as they encourage tearing of material. Tying the ends off and securing them to a stake or T-post, in combination with adding rope reinforcement over the covers, will keep covers in place through wind and weather events they may encounter.
Row covers are a powerful tool for extending the growing season, but their success hinges on one crucial factor: proper setup and upkeep. By ensuring the covers are securely in place and well-maintained, gardeners can take control of their growing season and maximize their harvest.
Anthony Reardon is a horticulture agent with Kansas State University Research and Extension. Need help? Contact the Johnson County Extension gardening hotline at 913-715-7050 or email garden.help@jocogov.org.
