By Jeannette Warnert
Fresno County gardeners can juice up their tomato yield in 2025 by planting grafted tomatoes, which are grown using a complicated and labor-intensive process that confers greater vigor and disease resistance.
Some 200 grafted tomato transplants will be available for sale at the UC Master Gardeners Spring Plant Sale, 7 a.m. to 5 p.m. March 21 and 22, at 907 E. Pico Ave., Fresno. The plants consist of varietal tomatoes grafted onto a wild-type rootstock. The “wild” root is what gives the plants improved performance.
“Last year, we only had a few dozen grafted tomato transplants. Their popularity has been growing and this year, luckily, we have many more,” said Master Gardener Susan Rosenthal, the volunteer who spearheaded the propagation. “I don't know of any nurseries in our area selling grafted transplants this season. They mostly have to be mail-ordered.”
Rosenthal started the rootstock and scion seeds in her sunroom, calculating germination so the rootstalk and cultivar stems – which grow at different rates – measure precisely 1.5 millimeters at the same time.
“The stem of the rootstalk and varietal have to be exactly the same size,” she said.
The two tiny plants are then placed side-by-side and delicately cut at the same angle, then secured together with a silicon clip designed for this purpose.
“That was the less challenging part,” she said. “The hard part was getting them to heal.”
After grafting, the plants were placed in humidity domes and kept in the dark at 70 to 80 degrees for two to three days. Ever so slowly they were exposed to more light and lower humidity. It took two weeks for the grafts to be fully healed, she said.
Because of this tedious process, grafted transplants are more expensive than those propagated using the standard practice. One gallon-sized grafted tomato cultivars – including Ace 55, Fourth of July, Juliet, Honey Delight, Verona, Brandywine and Celebrity – will be $12 each at the Master Gardener sale.
Along with these specialty tomatoes, hundreds of standard tomato transplants (priced at $8 each), and dozens of perennial and annual plants will be available at the plant sale.
Cash and checks are accepted (no credit cards). All proceeds support the non-profit UC Master Gardener Program of Fresno County.
