Extend Your Garden Season: Row Covers and Mulches

Extending Your Garden Season

Season extending has come a long way since I made my first cold frame more than twenty-one years ago. I can still remember that leaky, damp, rickety box, with the slanted front, the old, discarded window sash. Many gardeners continue to fashion cold frames from whatever materials they can find. Others rely on old standby covers, such as hot caps. Or perhaps they simply plant against the shelter of a warm, south-facing wall. This book will advise you on how to take advantage of a relatively new technique: row covers. You will find two main kinds of row covers: “floating” and plastic.

Floating row covers are soft, white “garden blankets” made of a lightweight, permeable material designed to minimize the effects of frost, harsh sun, and driving rain. They have the added benefit of protecting against insects. Because these row covers require no supports, they are known as floating row covers. Another kind of row cover is a thin, perforated or slitted plastic laid in the form of a tunnel and supported by wire hoops. Depending on the plastic, these tunnels provide variable frost protection and can generate heat — often in excess of 100°F. These row covers can also help warm-climate gardeners extend their growing seasons into periods when it’s too hot, rather than too cold. Growers use tunnels of opaque plastic or shade netting to reduce temperatures.

Plastic over wire hoops, weighted with boards

Hot caps

Before getting into more detail about row covers, here are suggestions for using some old-fashioned season extenders that remain a popular, low-cost choice for many gardeners. Cold frames, plastic cones, hot caps, plastic milk jugs with the bottoms cut away, hay bales, newspapers, blankets, plastic-wrapped wire frames, and even inverted grocery bags with their edges turned down and weighted with soil, all work well in certain situations.

A popular commercially made product is Wall-O-Water, which is an 18-inch-high, tee-pee-shaped plastic tent that protects plants from hard frosts. Wall-O-Waters are self-standing, 18-inch-high circular belts of plastic tubes filled two-thirds of the way with water. The first time I tried them, I noted a one-hour temperature gain of 14°F around my tomatoes. To keep temperatures from getting too hot, add more water to the tubes to make them more turgid and open at the top. With less water, their tops lean in, forming a teepee.

Cold frame

Milk jug with bottom removed

To protect tomatoes and other tall, heat-loving plants from frost or wind, erect a cage around the plant, then wrap the cage in plastic or fabric. Make the top removable, so you can close it at night and vent the cage in the day.

Garden suppliers also sell “high tunnels” or “tunnel greenhouses.” About 4 to 6 feet tall, these are larger, more-permanent season extenders. Usually supported with PVC pipe, wood, or some other inexpensive framing, they generally measure 12 to 16 feet wide and 12 to 24 feet long. They may be covered with new, durable plastics such as Polyweave, an 8-mil thick, fiber-reinforced polyethylene or Tuffbell 900N, made from polyvinyl alcohol. A less-expensive choice is 6-mil polyethylene. Companies often guarantee their materials for a specific number of years. As one season progresses to another, some gardeners such as New England author Eliot Coleman, systematically rotate high tunnels from plant to plant.

Wall-O-Waters

Wrapped tomato cage