Grafted Tomatoes: What They Are and Why Grow Them

Grafted tomatoes are produced when two tomato plants joined together.

The resulting plant exhibits the strengths of both its “parents.”

While grafting has long been a common horticultural practice, in recent years it has become a valuable technique in tomato disease management. Usually, at least one of the tomato varieties selected for the graft has outstanding disease resistance, most often a hybrid.

Tomatoes from grafts have been regularly produced in European and Asian greenhouses. Their popularity in the U.S. is on the rise.

Advantages of grafted tomatoes

They're bred to tolerate temperature stress (either too high or too low)
They're bred tolerate diseases
They're bred to tolerate over-watering or flooding
They're bred to tolerate a higher-salinity environment

As a bonus advantage, these tomatoes have bigger fruit and increased yield. Less stress and fewer diseases make it easier for nutrient uptake in plants so they can concentrate their energy on production.

(Check out different varieties of grafted tomatoes.)

Anatomy of a grafted tomato

One tomato’s roots are used and another tomato’s body is used for the graft.

Stock (or rootstock): the below-ground part of the tomato plant, used in a graft for its roots. This variety is chosen for the graft because of its resistance to fungal, bacterial, viral, and nematode pathogens, such as those pesky diseases like early blight, late blight, Septoria leaf spot, verticillium wilt, fusarium wilt, and bacterial wilt. Hybrid tomatoes are often the rootstock of choice since they have been bred for significant disease resistance.
Scion: the above-ground part of the tomato plant, used in a graft for its stems, leaves, blossoms, and fruit. This variety is chosen for the graft because of its fruit qualities. Heirlooms are a favorite scion, especially for gardeners who have a passion for a particular heirloom’s taste.

Types of tomato grafting

Tube grafting (or Japanese top-grafting): a fairly new technique that produces large numbers of plants quickly. Seedling rootstock and scion are severed and reattached with a clip during healing.
Cleft grafting: a V-shape in rootstock and wedge-shaped in the scion are held together with a clip during healing.
Approach grafting: notches on two stems held together with a clip during healing.
Micrografting: a new technique used primarily with hybrid tomatoes. Very tiny scions are grafted onto 3-week-old rootstock.

Several vendors offer grafted tomato plants.