Gardening Articles: Edibles :: Vegetables

The Tomato-Vetch Connection

by Jack Ruttle


If you're weary of purchasing fertilizer and mulch for your tomatoes every season, here's a way to get off that treadmill. Instead of buying, grow all that you'll need of both, during the off-season.

The technique is very simple. In late summer or early fall, you make a bed or beds for your tomatoes. Then sow the very hardy annual legume called hairy vetch, Vicia villosa. In spring you kill the vetch by simply cutting it close to the ground, and then lay it in place on the beds. Then set the tomato transplants right through the mulch.

That's it. Nothing to buy, and no need to dig, hoe, or weed. Do your regular staking, pruning and watering, and t he tomatoes will thrive until it's time to replant the vetch in fall, and yields will be as good as those you get with the method you are now using, and likely even better.

High yields, much less tilling and digging, and no need for compost, manure and other nitrogen fertilizers: If that sounds to you like a major breakthrough, you are not alone. This system has performed so well in USDA tests in Beltsville, Maryland, that researchers and farmers all over the country are trying it and expanding it to other crops.

Hairy vetch is hardy enough to grow in the far north (USDA Zones 5 and colder), the season length in those zones is too short to permit easy exploitation of the technique. In general, the hairy vetch-tomato rotation described here most readily adapts to gardens in zone 6 and warmer.

Beyond Plastic Mulch

This planting system evolved out of a search for an alternative to plastic mulch, which worked like magic on tomatoes. As a matter of fact, over the last 40 years, plastic mulch has radically altered vegetable growing, both for farmers and many gardeners. But plastic brings problems. It is expensive to buy and difficult to dispose of in a responsible way. Commercial growers have begun to complain loudly, especially about the disposal problem.

A few years ago, Dr. Aref Abdul-Baki and his colleague Dr. John Teasdale, horticulturists with the Agricultural Research Service in Beltsville, began thinking about the plastic-mulch-and-tomatoes problem and how to solve it. The most obvious benefit of plastic is the soil heating that advances harvest by one to two weeks. But plastic mulch also increases total yields, and it does that by keeping the ground moist and blocking weeds. The researchers realized that any organic mulch could perform these two functions just as well as plastic does, and probably better.

Good vegetable gardeners already know that. We mulch our tomatoes with leaves, grass clippings, hay, straw, compost or whatever, and the results are great. But Abdul-Baki and Teasdale were thinking more about farmers, who would want to know exactly which mulch is ideal, where to get it cheap and how to put it on fast. If the researchers were to suggest the farmers use shredded leaves, straw or compost, they would probably reply, Just what we need! More work and more stuff to buy! We'll keep the plastic and its early yields, and deal with the other problems as best we can."

So the researchers began to look for mulches that farmers could grow themselves in the off-season, so mulch-growing wouldn't tie up valuable ground. And they pretty quickly settled on the idea of a winter-hardy annual, something that was easy to kill in spring and could maybe even be grown right where the vegetables would be planted. The method worked well from the start, and the best plant, in most regions, turned out to be hairy vetch.

The tomato-vetch trial plots, using no nitrogen fertilizer and without any weeding, have consistently outyielded plastic-and-fertilizer plots by about 25 percent, and fertilized bare soil by 100 percent.

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