Side-by-side tests run by Ball Horticultural Co. show at least 50 percent higher yields from grafted tomato transplants, left, over non-grafted varieties, right. (Robin Bachtler Cushman/AP)

The best way to make progress in horticulture is not to leapfrog over common wisdom into a void of profitable but risky novelty, but to retrace our steps back to an old, sound technique and forge a new path with it, taking full advantage of what we’ve since learned about the natural world.

A case in point would be the recent popularity of grafted tomatoes, in which one variety has its top removed to receive the leafy stem of another. Soon, the stems knit together so that the first variety provides the roots, the second the top growth and tomatoes.

Fruits such as apples have been grafted for centuries, and Asian experiments with herbaceous edibles such as watermelons were begun nearly a century ago. But grafted vegetables have been slow to catch on in this country, where it’s always the newest F1 hybrid that rules, and the shortcuts of chemical aids and transgenic engineering always beckon.

We’ve been grafting tomatoes and eggplants at our farm for several years now, and how productive they have been! Just as with apples, a variety bred for deliciousness is grafted onto a rootstock that, if allowed to bear, would produce small, inferior fruit. What the rootstock variety brings to the partnership is a larger, more vigorous root system that lets the plant take up more water and nutrients. Rootstocks are also developed for their resistance to the many ills that can befall these plants (tomatoes, especially), which are mostly from soil-borne fungi, bacteria and nematodes.

This means that you do not have to use products such as the soil fumigant methyl bromide to keep the plants healthy. And you can grow heirloom varieties — big on flavor but often low on productivity — to your heart’s content. There are also rootstocks that enable plants to withstand extremes of hot and cold, wet and dry — even salty conditions.

I’m not the one who does the grafting at our place, and am happy not to. Vegetable grafting is basically plant surgery performed in sterile conditions on tiny, fragile stems, followed by a recovery period in a climate-controlled “healing chamber” under careful supervision. For gardeners eager to meet that challenge, there’s a good article published by North Carolina Cooperative Extension Service called “Grafting for Disease Resistance in Heirloom Tomatoes (go to and look under “Research”).

Johnny’s Seeds also has a video demonstration at (under “Videos”). If you grow a lot of tomatoes and favor grafted plants, doing it yourself might be a necessity, because commercially grafted plants cost about $8 and up. But many nurseries have started to carry them, and the price will likely come down. Park Seed, Burpee, White Flower Farm and Territorial Seeds are among the many mail-order sources.

I’ve heard a few comments about grafted tomatoes with vines too rampant and fruits too big, with watered-down flavor. But most gardeners are delighted that they can now have their heirlooms and eat them, too. Ours have tasted fine. To me, it seems like a trend that will be a win-win all the way for America’s favorite vegetable crop.

Damrosch’s latest book is “The Four Season Farm Gardener's Cookbook.”

Tip of the week

Check the condition of your shovels, forks, hoes and other garden tools and repair or replace them in advance of spring gardening. Take the opportunity to clean off mud and to sharpen blades with a steel file. Wiping with an oily rag will keep surface rust away.

— Adrian Higgins