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's 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. (Don't forget to save your tomato seeds; here's how.)
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. Grafted plants are great way to grow your favorite tomato in huge amounts. Once you start grafting, you might never settle for less.