'Greenhouses' guard tomatoes against early frost

The tomatoes -- red, ripe, and delicious -- have been coming in fast ever since late July (I've been eating three a day on average) until a week ago. Suddenly, the abundant flow has become a trickle. But there is promise of many more to come (a miniglut, almost) if I can protect those green and tender tomatoes from the first frosts of fall.

The very weather -- warm days and chilly nights -- that puts such fiery hues into the leaves of the alders, maples, and other hardwoods takes the color right out of tomatoes. not only does frost threaten the plant itself, but cool weather delays the ripening process as well, and this accounts for the sudden slowdown of my harvest.

fortunately, there is something that can be done both to speed the ripening and to protect the plants from frost. Actually, it's pretty straightforward and you might like to try it:

Take some welded fencing (chicken wire will also do but you will need more supporting posts) and place it in a circle around your tomato plant. Don't make it a complete circle. Leave a 6-inch gap down one side so that you can reach in to pick the fruit. Make the fence circle about as high as the tomato vine.

Now wrap clear plastic sheeting around the fence and attach it to the fence with clothespins or similar devices. Have the two ends of the plastic overlap by about a foot. Make sure that the ends coincide with the gap in the fence so you need only unwrap a few inches of the plastic when you come to pick the tomatoes.

What you have now done is wrap a clear thermal blanket around your tomato vine. It will love you for it. The sun, shining through the plastic, will warm the vine even when the chill fall winds blow. At the same time there will be adequate air exchange through the open top.

The open top, however, must be covered over in the evening with pieces of wood, old sheets, or blankets -- whatever is available -- to slow down the loss of heat from around the plant. Even covering the plastic with additional material will help.

Meanwhile, the growing popularity of passive solar housing has shown us the value of heat-storage materials, often referred to as thermal mass. They absorb the excess heat during the day and then radiate it out around the plant at night.

A simple way to store heat around your tomato plant is to sorround the base of the plant with a mulch of rocks, stones, or bricks.

Plastic jars filled with water will also do an efficient job of storing heat. Cut away some of the lower leaves from the tomato vine so that the sun can directly strike the surface of the stone or water bottles.

When more than a mild frost threatens your area, you can improve the situation still further by filing a plastic milk bottle or similar container with hot water from the kitchen faucet and placing it at the base of the plant. This will have the same pleasing effect on your favorite tomato vine as the old-fashioned hot-water bottle had when taken to bed on a cold night.

Of course, there are many variations on this theme. Any frame with a covering of plastic will form an acceptable greenhouse for this time of year. Perhaps the simplest method of all is to stretch a line between two poles and then throw a sheet of plastic over the line, anchoring it a few feet out either way with bricks or soil. this way you will have formed a plastic tent that will help your plants through the early light frosts of fall.

Naturally, tomatoes aren't the only tender garden crops you might want to protect. Among them are zucchini squash, peppers, and eggplant; they'll all go on producing for you if you can just make the nights a little bit more comfortable.

I recall one fall several years ago when an early frost put an end to the tomato crop. At the time I figured we had twice as many green tomatoes on hand as we had picked ripe ones during the summer. The frustrating and tantalizing part of the whole experience was the weather during the following four weeks We enjoyed the most perfect of Indian summers -- warm, windless days without even a touch of frost.

Had I protected those vines on just that one occasion, I believe we would have doubled our tomato harvest that year.

We'd have had a lot more zucchinis, too.