In many of the seed catalogs arriving soon in mailboxes, the headliners will be grafted vegetables, in which one or more different varieties grow from a single rootstock. Tomatoes seem to be the grafted transplants most frequently offered, providing greater disease tolerance, bigger harvests, increased vigor and better taste.
Side-by-side tests done by Ball Horticultural Co. in Chicago have shown at least 50 percent higher yields from grafted tomatoes than from non-grafted varieties. That total varies from garden to garden and gardener to gardener, but it means more fruit or larger fruit.
Grafted plants are also pricier, in part because grafting is labor intensive.
“You’re also paying for disease insurance and a greatly improved yield,” said Scott Mozingo, product manager for Burpee Home Gardens, a Ball Horticultural subsidiary. “You’re paying more but what you’re getting is so much more.”
Grafting is an ancient horticultural practice that fuses tissues from one genetically different plant to those from another, combining, for example, disease management with heirloom flavors. Think apple trees, grapevines and roses.
Vegetables have been late entries in large-scale grafting programs intended for home gardeners, particularly in the United States. But that is about to change.
“It’s been primarily because the (horticultural) industry here hasn’t been set up for it,” Mozingo said. “Grafted vegetables have been big in Asia for 70 years. In Europe, for about a decade. It’s been largely a supply problem, but I think they’re going to be a very big thing in seed catalogs next season. A very big thing in retail, too.”
Grafted plants aren’t any more difficult to work with than nongrafted ones, but do require slightly different management. That includes:
Planting them deeper. “They’re tall tomato plants so they need a deeper base,” Mozingo said. “But don’t bury the grafts. Those should be above the soil line or you cancel out the benefits.”
Pruning. “The plants are so vigorous that they produce a lot of vegetative material,” said Josh Kirschenbaum, product development coordinator and spokesman for Territorial Seed Co. in Cottage Grove, Ore. “There won’t be as much fruit production if they don’t get pruned.”
Adding trellises. “Towers or cages are pretty close to being mandatory,” Kirschenbaum said. “These plants are so energetic and grow so tall that it’s important you give them some kind of support.”
Easing off on the chemicals. Grafted vegetables have better natural defenses against ground-borne diseases and insects. Fewer pesticides and herbicides are needed.
The potted plants will be offered with single or double grafts. Grafted peppers and eggplant will be offered along with tomatoes in many catalogs. Grafted cucumbers and watermelons may be added to the inventory once nurseries solve the logistics.
“Both vine out pretty quickly,” Kirschenbaum said. “We aren’t ruling them out, but we will have to come up with a clever way to get those plants shipped to our customers.”
At least one additional benefit can be derived from gardening with grafted plants: their entertainment value.
“It’s fun to say you can grow red cherry tomatoes and orange cherry tomatoes on one plant,” Kirschenbaum said. “Or Beefsteaks with a Roma.”