Grafted tomatoes bring together the best of both worlds: excellent production and disease resistance, even on the fussiest varieties.
“We’ve seen a yield boost of 30 to 50 percent,” says Andrew Mefferd, tomato expert at Johnny’s Selected Seeds. “[The plants] go on forever. They have so much stamina. They keep fruiting until frost.”
Grafting is simply taking the top (scion) of any tomato variety seedling that is the same stem size as the rootstock, and attaching it to a specialized hybrid rootstock grown specifically for its vigor and disease resistance. The rootstock provides protection from tomato mosaic virus, nematodes, verticillium wilt, and a number of diseases based upon that specific rootstock. For instance, ‘Brandywine’ tomatoes succumb to a number of diseases. If they’re grafted to ‘Estamino’ rootstock, which is resistant to seven tomato disease issues, they garner that benefit.
Jack Manix, of Walker Farm in Dummerston, Vermont, needed some way, short of removing the soil completely, to combat soilborne pathogens in his greenhouse tomato-growing operation.
“We grow organically, but can’t follow one of the main principles: crop rotation,” he says. “We had to try something different.”
They began grafting all of their ‘Buffalo’ variety (which Manix says is an excellent-tasting tomato on a wimpy plant), and never lost one. Now they graft all of their own, as well as 3,500 plants for other growers.
Grafting is a huge boon for commercial growers and small farms producing for the market, but it’s also a benefit for home growers who want to grow heirlooms or varieties that otherwise produce marginally in their region.
There are plenty of grafted plants available, but gardeners looking for an organic alternative will probably have to create it themselves.
Tomato grafting isn’t difficult, but it requires a little practice and an investment in the rootstock seed, which can cost nearly 50 cents per seed. Grafting clips, either the small silicon clips for top grafting (roughly $.14 apiece) or the spring-loaded larger grafting clips ($.44 per clip), are the best to use since they are easy to attach and are reusable. Some people try using tape or even grafting tape, but it’s a challenge with the delicate tomato stems.
“It’s something for the really serious home gardener,” says Mefferd.
The most important part of a grafted plant is the rootstock. There is a growing number of options out there, although most are not organic seed.
Johnny’s offers organic seeds of the variety ‘Estamino’. It’s a “generative” type rootstock, which means it puts more energy into fruit production rather than plant growth. The drawback is it doesn’t handle stress as well as the “vegetative” types, such as ‘Maxifort’, a standard for many growers because of its exceptional growth and durability.
Mefferd says with the generative rootstock, “You may have better luck with smaller fruit and shorter crop time.” It’s ideal in areas such as the Pacific Northwest where heat stress is not an issue.
On the other hand, the vegetative rootstock is good for big-fruited tomatoes, long seasons, plus it handles the heat well.
For the scion, you can use practically any top variety you want, although if it’s well matched, such as small-fruit tomatoes on a generative rootstock or the larger varieties on the vegetative kind, you’ll have better success.
As a general rule, start your rootstock and scion plant at the same time so the stem diameters match when it’s time to graft.