The Biggest Thing in Tomatoes Since Hybrids
by SCMG Steven Hightower
Grafted heirloom tomatoes are the latest thing in vegetable gardening this year – at least as far as the magazines and blogs go. They don’t seem to have made their way very far into Sonoma County yet, and while it’s late this year, next year might be a time to give this trend a try. Grafted tomatoes and other vegetables have been big in Europe and Australia for years, but represent a new trend in the US. Once you understand the benefits, it's easy to see why.
The answer may be this new trend of heirloom tomatoes grafted on hardy and resistant rootstock. Ready-grafted plants are available from several sources online including SuperNaturals and Ezra’s Organics in Oregon, and by next spring may be in several nurseries around Sonoma. They cost substantially more than regular tomatoes of the same size--$8 or so per plant--but the extra yield and problem-free growing should be well worth it. Actually grafting your own looks like it can be a bit tricky, and we’ll get into the details of that next spring.
The end result of growing grafted tomatoes appears to be high production of fabulous heirloom breeds, with lower susceptibility to pests and diseases. Higher resistance does not, of course, come with guarantees. San Mateo Master Gardeners embarked on a trial to compare grafted to regular tomatoes for yield and vigor in 2011, and both the grafted and regular beds succumbed totally to late blight due to a soil infection.
The root balls of grafted tomatoes can stretch 4 to 6 feet wide and deep, compared with a regular tomato root mass of 2 to 3 feet. This root mass of grafted plants draws more water and nutrients from the soil, so they need less irrigation and fertilizing. The vigor from this extended root mass helps them deal with heat spells, and they also keep ripening longer when temperatures drop in the fall. Grafted tomatoes will grow substantially taller and fuller than ordinary heirlooms, and have to be supported early and well. Grower Ezra’s Organics states that they will grow to six to twelve feet in height. Their size also makes them less suitable for container growing.
Andrew Mefferd, a crop tester and tomato expert at Johnny’s Selected Seeds, a Maine-based online retailer, was recently quoted in the New York Times saying “We’ve seen a yield boost of 30 to 50 percent,” and calls grafted tomatoes “the biggest single change since people started hybridizing tomatoes in the 20’s." Some sources are claiming even higher production.
Normally I find the “if it sounds too good to be true, it probably is” rule to be pretty reliable. Grafted heirloom tomatoes may be the exception to the rule. Let’s all find out next spring.