How Eliot Coleman Uses Low Tunnels

After transplanting,  the crops get a layer of row cover in mid-October, just like the onions. Overwintered lettuce and spinach can be ready for market as much as a month ahead of the earliest spring transplants. Pick varieties tough enough to handle the stress of winter.

When serious winter weather is on the way (late November or early December), add a 10-ft-wide sheet of clear plastic over the row cover so the low tunnel can shed snow. Pull the plastic tight so the structure resists wind and snow. One way: drive a stake 4 ft beyond the last hoop at each end, tie a rope to each end of the plastic, pull both ropes as tight as possible and tie them off to the stakes. That tensions the cover end to end; then reposition the sandbags along the edges to tension it side to side.

Holding the edges down with sandbags is quicker and easier than burying them, though less permanent. A very strong wind can lift a sandbagged cover, but once winter sets in and everything freezes in place, it stays put. Sandbags also let you cover pairs of beds side by side across a whole field, since you don't need space to dig a trench and pile soil as you do when burying edges.

In spring,  begin venting the tunnels on sunny days. Pull a few sandbags off the south side and slip in a notched stick to prop up the edge of the plastic and fabric. When the weather has warmed enough that the fabric alone is enough protection (around late March), take off the plastic and store it for next winter.