The first frost typically marks the end of the growing season for vegetable gardens. But with the popularity of season extenders, many gardeners now grow vegetables year-round. In Arkansas, we typically have fluctuating winter temperatures, so constant coverage is usually not necessary all winter long, but planning makes unexpected low temperatures manageable.
As the name implies, season extenders allow gardeners to continue growing vegetables well past a killing frost. Season extenders can be as elaborate as high tunnels or as simplistic as inverted flowerpots or cardboard boxes. Choices include low tunnels, cold frames, hot beds and cloches.
Low tunnels are temporary structures that can be put over vegetable plants. The height is usually 3 to 4 feet and as wide as your rows of vegetables or raised bed. Hoops, made of wire, bamboo or plastic, should be spaced out every 3 to 4 feet for the length of the tunnel. The framework will be covered with row covers or plastic to create a mini-greenhouse to protect plants during cold weather. Most row covers, depending on grade, will provide protection down to 24 to 28 degrees, and are water, air and light permeable.
Cold frames and hot beds can be used to effectively grow cool-season crops in the fall and spring. In the fall, crops may be directly seeded into soil under the cold frame or grown in containers in beds. The beds may be used in the spring to start seeds as well as harden off maturing seedlings. Cold frames and hot beds collect heat as the sun’s rays shine through the primary bed covering and heat the interior of the bed. The bed covering may be made of glass (old windows work great), plastic, fiberglass or something similar.
Often the bed covering will be installed at an angle to capture as much sunlight as possible. The primary difference between a cold frame and hot bed is that a cold frame uses only sunlight to heat up, while the hot bed uses either an electric heat mat or other outside heat source.
Traditionally, cloches were glass, bell-shaped coverings placed over individual plants. Over the course of time, the term “cloche” has been expanded to include individual coverings made from any type of material. These temporary coverings may be constructed of wood, fabric, plastic or other material; an inverted flowerpot or cardboard box can work well.
Regardless of the type of season extender you choose, the goal is to protect cool-season vegetables from freezing temperatures and allow them to grow all winter. This requires you to pay attention to weather conditions and be prepared to cover as needed. Moisture control is also important. Prior to a hard freeze, ample moisture in the ground can serve as a buffer to colder temperatures.
Just because the winter season is beginning, you don’t have to put up your shovels and wait for spring. Keep gardening!