Growing grafted vegetables

Once a week from June 14 to mid-September, Harry Olson and Tobie Habeck commuted from Salem to Silverton to tend a U-shaped plot at The Oregon Garden. As they weeded and watered, the duo would hear docents tell their trams full of visitors about the little-known grafted vegetables overflowing from the raised beds and spilling onto the mulched aisles.

The two longtime Master Gardeners with the Oregon State University Extension Service would look at each other and smile. This was why they toiled. People need to know, Olson said, about these vegetables that have garnered so much attention around the country, including stories in USA Today and the New York Times.

The plants are a combination of the hybrids and heirlooms we love attached by hand to the roots of vigorous plants in a process similar to grafted roses, fruit trees and grapes.

Tomatoes were first to the grafting table. The new version of the old favorite hit the market in 2010. The next winter, Olson sat down with Territorial Seed’s catalog, opened the front page and stared at the photo that showed a non-grafted and a grafted tomato side by side.

“My immediate thought was that it was hocus pocus,” Olson said. “I pushed it aside and went to Google and read for four hours. About 30 minutes into it, I had a flash, ‘This is real.’ And then I realized what a great opportunity it was for Master Gardeners to step in and do a trial so people can see it and make up their own minds.”

Habeck, president of Extension’s Master Gardeners for Marion County, was also skeptical at first. The price of grafted vegetables is high, about twice that of a normal plant. What, she thought, could possibly make it worth that much? Now she’s a true believer in the insect- and disease-resistant tomatoes and other vegetables that make up for their cost with harvests at least twice that of their ungrafted brethren.

For three years, Olson and Habeck planted, tended and harvested grafted vegetables at the Marion County Master Gardener’s demonstration garden behind the Extension office in Salem, but traffic was spotty. This year, by an invitation brokered by Master Gardeners Charles and Mardean King, they transferred their energy and efforts to The Oregon Garden where 50,000 to 60,000 saw the garden at stop No. 5 on the garden tour.

Ty Boland, horticulture manager at the 80-acre garden, said, “We had been interested in grafted vegetables, but never saw a side-by-side trial. With these growing near our regular ones, it was a real eye-opener. The information Harry and Tobie put out there was fantastic. We definitely saw the value in the yield and vigor of these plants.”

The response from the public was gratifying, too. First people were drawn to the brightly colored ‘Icicle’ tomatoes in red, orange and yellow. Then they’d see the cute lavender-and-white ‘Ping Tung’ eggplant and the carpet of grafted ‘Sugar Baby’ watermelons.

“The watermelons stole the show,” Olson said. “They don’t usually grow very well here, but every week when we came out, they had sent out runners into the walkway. Those two plants produced a dozen basketball-sized melons.”

Melons, eggplants, cucumbers, peppers and basil are now on the market, but tomatoes, including grafted versions of the antioxidant-rich, purple Indigo series bred by Jim Myers, OSU’s vegetable breeder, are the money-makers.

“People wanted to talk to us. They told us they would grow grafted vegetables next year,” Olson said. “This is what Extension and Master Gardeners do. The garden was all about public education and introducing new horticultural things to the people. It was amazing.”

Tips for growing grafted tomatoes

When it’s time to plant next spring, follow these instructions.

-- Be careful when planting. Traditional tomatoes can be planted deeply because roots sprout all along the stem. With grafted tomatoes, it's important not to bury the graft because it will produce roots from the original plant without the benefits of the grafted rootstock. Plant at the same level as the top of the soil in the pot.

-- Remove any suckers that come up from the roots, and any roots that form above the graft line.

-- Stake, trellis or cage grafted plants as they are very vigorous and tall and shouldn’t be allowed to fall to the ground.

-- Get even more fruit by guiding the plant so that you get two to four main stems. You can even pinch out the main stem to direct growth evenly into side stems.

-- Prune most of the side branches (suckers) out of indeterminate tomatoes (those that keep bearing throughout the season) so that energy goes into producing fruit. You may pinch the top out of plants when they reach desired height. That will help force fruiting on the lower plant. No pruning necessary for determinate varieties.

-- Keep 2 feet between tomato cages so that plants get plenty of air circulation and light from all sides. Remove lower 12 to 14 inches of branches to avoid soil diseases splashing up during watering.

-- If you grow in a container, use a big one; a whiskey barrel is about the right size.

-- Fertilize and water as you would regular tomatoes.

­­-- Stop watering  tomatoes by mid­August. (Except in containers.) This will improve fruit quality by concentrating flavors.

­­-- Expect (barring frost) about an extra month of good production from grafted plants.

Image above: ‘Indigo Cherry Drops’ are one of a series of tomatoes bred by OSU's Jim Myers. Photo by Robin Bachtler Cushman

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