KENNEWICK, Wash. -- What's the favorite vegetable crop of home gardeners?
You guessed it -- tomatoes. The next big thing for tomato-growing gardeners is grafted tomatoes.
In the future, you will be reading about them in gardening publications and seeing them for sale at local garden centers and in mail-order catalogs.
What is a grafted tomato? It's a horticultural technique that joins two plants together. The desired fruit producing variety of a plant is attached to the roots of another variety. The top fruit producing part of the joined plant is called the scion, and the lower portion with the roots is called the rootstock.
Most fruit trees are grafted because their seed does not produce the same variety as the parent tree because of cross pollination. Grafting also is used when a rootstock can impart certain qualities to the grafted tree, such as dwarfing and winter hardiness.
Desirable varieties are grafted onto rootstocks to increase plant vigor and production, improve disease resistance, and improve tolerance of stress from flooding and drought.
Is grafting of tomatoes a new practice? Not really. Vegetable grafting started in Korea and Japan in the 1920s when watermelons were grafted onto squash rootstocks. From there, vegetable grafting has spread around the world and is commonly used for intensive commercial production of some vegetables. Tomato grafting started increasing in popularity around the world in the 1960s, but wasn't introduced in the U.S. until about 20 years ago.
Now gardeners are beginning to hear about grafted tomatoes. The use of rootstocks with heirloom tomato scions can help provide greater disease resistance for these old tomato varieties that have little resistance to many diseases that plague gardeners.
What other types of vegetables can be grafted? Tomatoes, eggplants, peppers, melons, cucumbers, and squash can all be grafted, but grafted tomatoes are most common in commercial vegetable production in the U.S.
Are grafted tomatoes really better or is this a gimmick? Whether local gardeners will find that these plants perform better for them isn't known yet, but grafted tomatoes are not a gimmick. When a representative of Ezra's Organics (ezrasorganics.com) was in our area in late May trying to convince local nurseries to stock their grafted tomatoes next year, he donated two grafted plants to the Master Gardener Demonstration Garden. He also donated two of the same varieties of nongrafted plants so a comparison could be made between the grafted and nongrafted plants. Visit the Vegetable Garden in the Demonstration Garden to see how they're doing.
Where can I learn more about grafting tomatoes? WSU has a new online publication, "Vegetable Grafting -- Eggplants and Tomatoes." Just go to pubs.wsu.edu to find it. A companion fact sheet is "Vegetable Grafting: The Healing Chamber."
* Marianne C. Ophardt is a horticulturist for Washington State University Benton County Extension.