by John Bombardiere, Extension Agent
March is perhaps the most unpredictable weather month of the year. Temperatures can be near 70 degrees one day and in the 30s the next, so it’s hard to believe any plants outside of a greenhouse could still be growing given the fluctuating climate. The kale and chard in our raised beds gave up in January and February after hanging on throughout a mild early winter, and we have several months to wait before we can plant peppers and tomatoes in the garden again. But there are a few places in the state that still are producing lettuce and greens. High tunnels have been installed on hundreds of West Virginia farms over the past few years. These structures consist of a metal frame, wooden baseboards and plastic covering. They can keep frost off plants in the fall and early spring, and in combination with row covers, can keep lettuce and greens alive and well during even the coldest nights.
For early spring planting outdoors, a few options exist. For frost-sensitive plants, row covers can be used to get fruiting vegetable transplants off to an early start without suffering the consequences of an unexpected frost. These are often called “floating” row covers because they can lay over the plants without harming the leaves like plastic covering will do. For individual rows, hoops made of wire can support the covers. This is called a low tunnel. This saves material and allows for better access to and monitoring of plants. Brands of row covers include AgriBon and Remay. These can be ordered from seed and garden suppliers. Locally, feed and hardware stores sell tobacco cloth that serves the same purpose.
Soil temperature is important for early seed starts outdoors. In order to start seeds in late April and early May, clear plastic mulches are used. The clear mulches transmit solar radiation into the seedbed, warming the soil to proper temperature to allow seed germination. This is a common practice for early direct seeded crops such as green beans and sweet corn.
For more information about high tunnels, ground cover and plastic mulches see the following links:
- High Tunnels (WVU Extension Service)
- Use Row Covers to Extend Your Season (Rodale’s OrganicLife)
- Plastic Mulches (Penn State Extension)
- Season Extension Options (The University of Maine)
Finally, always remember to check your city’s ordinances pertaining to the erection of such structures before beginning construction.