Lowther: ‘Caterpillars’ can save crops

Last week I mentioned how cold frames can extend the season well into fall and winter, but even something as simple

Last week I mentioned how cold frames can extend the season well into fall and winter, but even something as simple as a clear plastic tunnel can do the trick.

Protecting the plants can mean eating fresh from the garden for several more months, perhaps right through the winter, provided you’ve got a handle on the slugs. Have I mentioned before how much I hate slugs?

But I digress. Cold frames don’t need to be complicated to make, but the easiest to use and longest lasting is a bottomless box with a glass or clear plastic lid like the one my David made. Experimentation has found that the traditional low-angled frame with a gradual slope to the lid held just above the plants works best, perhaps because there’s less space to heat. The recommended height is eight inches along the front side and 12 inches along the back.

David attached strips of wood along the bottom edges so that when it rots he can just replace the strips instead of the whole box.

Before I thought of covering the glass windows with sheets of clear plastic, water pooled at the lower edge and froze. Now rain slides right off. This is my third fall using a cold frame and I hope the solarizing method I wrote about last week to eradicate hungry bugs works this year. Death to slugs!

Here’s another idea I’m trying this year: a cover a crop that is not quite winter hardy with a clear plastic tunnel.

I’ll leave it on all winter. Celery turns to mush and carrots split when exposed to cold winter rains, so I’m trying this out on them. The French cover fields of crops like this and call the tunnels “chenille”, which means “caterpillar” because a field of them looks like huge caterpillars, not, as one might think, because caterpillars love its nice cozy microclimate.

They use six and a half-foot lengths of No. 9 gauge wire, enough to span the bed and clear the plants and penetrate the soil 12 inches at both ends. I’m using half-inch electrometallic tubing (emt) that I bent to fit the bed, sheathed over short lengths of quarter-inch rebar hammered into the soil, because that’s what I’ve got. The wire or EMT span the bed every four feet. A long sheet of clear plastic drapes over the hoops, attached at both ends of the tunnel to stakes driven into the ground to keep the plastic taut. To keep the plastic tight, prevent the wind from blowing it off and to enable the plastic to be drawn up on hot days, twine is taken across each arch of plastic, from one side to the other, attached diagonally to alternate hoops at soil level. The wires are twisted into small circles at soil level ahead of time for the twine to attach to. I used zap straps on the rebar to attach the twine to.

The plastic is cut at soil level along the sides and the tension of the twine on the plastic holds it up. The French orient these tunnels so that the side they never open faces the prevailing wind.

I’m still waiting for Indian summer, and I still hate slugs.