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How To Graft Vegetable To Boost Yields
You can boost tomato yields by as much as two thirds by grafting high-yielding varieties onto hearty rootstock. Grafting can also deliver modern hybrid disease resistance to heirloom tomatoes. Johnny’s Selected Seeds offers the supplies and know-how needed to make successful grafts.
“Our trials have demonstrated increased vigor and disease resistance with our grafted tomatoes,” says Andrew Mefferd, vegetable and grafting technician at Johnny’s Seeds.
The idea and techniques for grafting vegetables have been around for a century or more. But the practice of it has been most common in Europe and Asia where land is at a premium. University extension researchers and companies like Johnny’s Seeds have started testing and promoting the idea. Andrew L. Thomas, horticulturist, Southwest Research Center, Hoberg, Mo., suggests that grafting can double yield, reduce need for pesticides and increase vigor. He’s had great success grafting watermelons.
Carey Rivard, Kansas State University, Olathe, Kan., teaches workshops on vegetable grafting. He says grafting tomatoes is easy and credits Richard Hassel, Clemson University, with refining the more difficult watermelon grafting.
The extra labor is one reason vegetable grafting is most popular with high return, greenhouse production. Mefferd uses it for his family’s market gardening farm. Based on his experience and the trials, he recommends it for home gardeners as well.
Using hoop house tomato trials at Johnny’s Seeds in Albion, Maine, Mefferd grew two sets of three plants each of five popular tomatoes. These were grafted to Maxifort rootstock that has proven itself in greenhouse production. In the trials, one set of each variety was grafted while the second set served as a control for yield comparison. The plants were set out in the hoop house May 21 and harvest ended at the beginning of October.
“The grafted varieties averaged 40 percent higher yields,” says Mefferd. “The variety Geronimo yielded 66 percent more tomatoes when grafted.”
Yields varied from as little as a 3-lb. difference for Arbason tomatoes to a 12.9-lb. for Geronimos. The well-known variety Big Beef showed a 7.2-lb. increase when grafted.
Grafting of vegetables like apple trees requires cutting both plants on the same bias at a point where the stems are the same diameter. Johnny’s offers detailed instructions as well as the small clips that are used to hold the stem pieces together as they heal. Because some varieties grow faster than others, the rootstock and varieties to be grafted may have to be planted on different schedules in order to have the right diameter stems on each.
Mefferd recommends running a germination test on seed to establish speed of germination and growth. Planting may only need to be varied by as little as a day. Seed stock for grafting should be planted 6 to 8 weeks before grafting is planned. The grafting process slows growth and delays plants reaching transplant stage by 1 to 2 weeks.
A simple way to tell if plants are ready to graft is to place a grafting clip on a representative stem. If it fits snugly, timing is right.
The work area should be washed down with bleach solution or another antiseptic. Always use new blades and clips to avoid spreading disease.
Once the stems have been sliced through and clipped together, they should be placed in a high humidity, low light environment. This can be under a dome or in a plastic tent or tunnel. Humidity should be at 80-90 percent during the healing process, and the temperature should be between 71° and 74°F.
The healing process takes a week or so and requires daily checks and gradual venting. By the end of the week, plants should handle normal growing conditions without wilting.
“Grafting takes time and attention, but it’s well worth it for maximum production per plant,” says Mefford. “It’s also a great way to grow heirloom tomatoes that don’t have the resistance to soil-born diseases that newer varieties have.”
For detailed instructions and photos, including video, visit Johnny’s website. Although the company did trial sales of grafted varieties in 2011, there are no plans to repeat that in 2012. Silicone grafting clips sized for 1/16-in. stems are priced at $13.60 for 200. Spring-loaded clips which fit stems from 1/16-in. to 5/32-in. are priced at $40.95 for a pack of 200.
Contact: FARM SHOW Followup, Johnny’s Selected Seeds, 955 Benton Ave., Winslow, Maine 04901 (ph 207 861-3999; toll free 877 564-6697; www.johnnyseeds.com).

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2011 - Volume #35, Issue #6