That’s the question about grafted tomatoes: Why all the hubbub?
While the technique of grafting isn’t new to the plant world, the widespread availability of grafted tomatoes among home gardeners is—and it’s noteworthy, with more than a million grafted tomato plants shipped to nurseries and mail-order companies nationwide earlier this year.
Two things set grafted tomatoes apart from the pack in research trials: Not only are they more productive—they’ve been proven to produce 50 percent or more fruit—but they also resist soilborne pests and diseases in a wide variety of climates.
Growers use a graft clip (above) to hold together the scion (top of the plant) and the rootstock (bottom of the plant). When planting grafted tomatoes, always keep this graft joint above the soil level.
What is grafting?
Grafting is the practice of taking the top of one plant, called the scion, and attaching it to the root system of a different plant, called the rootstock. Growers have used grafting for centuries for woody plants, such as roses and fruit trees. But only recently has it become popular in the U.S. for growing tomatoes and other vegetables.
With grafting, which is typically done by hand, you get the best of both worlds: the desirable qualities of your favorite tomatoes from the scion (color, flavor, texture) with improved disease-resistance and production from the rootstock.
Grafted vegetable plants have been the norm in commercial vegetable production for decades in much of the rest of the world, particularly in Asia In the U.S., commercial tomato growers have used grafted plants in greenhouses for many years to fight disease and dramatically boost production, especially in situations where crop rotation is difficult. Until recently, however, grafted tomatoes were actually deemed too vigorous to be practical in residential settings.
Grafted Brandywine Red
Strength from wild stock
Today’s newer rootstocks have been bred for backyard green thumbs. The Mighty Mato-brand rootstock, for example, dubbed SuperNatural, is a hybrid of two wild tomatoes, crossed to provide more fruit and natural resistance to soilborne diseases, such as tobacco mosaic virus, verticillium wilt, fusarium wilt and nematodes.
Though grafted tomatoes aren’t resistant to airborne illnesses, trials have found that overall improved plant health makes the plants less susceptible to blight as well as temperature swings.
Grafted plants—tested in nearly every corner of the country, plus Canada, in recent years—have consistently produced tomatoes earlier and later in the season, sometimes right up to frost. And they don’t fade as quickly in drought.
Grafting isn’t limited to tomatoes; grafted peppers and eggplants were also sold for the 2013 season. Eggplants, according to growers, benefit even more than tomatoes from grafting. By 2015, we can expect to see melons, cucumbers, squash and even basil grafted for home gardeners.
Grafted Indigo Rose tomatoes are ripe and ready to eat when their undersides turn red.
More than 50 grafted tomato varieties—hybrids and heirlooms—were sold this past season, including cherry tomatoes like Sun Sugar, Yellow Pear and Sweet Million, saucers like San Marzano and Amish Paste, and slicers such as Big Beef, Pineapple, Mortgage Lifter, Black Krim, Brandywine and Cherokee Purple.
Hot new tomato varieties reached more gardeners this year thanks to grafting as well, including the Indigo series, billed as the first purple tomato in the world to be rich in anthocyanin, a health-boosting flavonoid also present in blueberries.
More Indigo series plants will come to market in 2014, including Indigo Sun, Indigo Ruby and Indigo Starburst, as well as a 7-pound tomato heirloom called Big Zac.
Bumblebee Pink grafted tomato
Bumblebee Pink and Bumblebee Purple—two new striped cherry tomatoes—made their debut on grafted rootstocks this season. Territorial Seed Co. sold double-grafted tomatoes (two tomato varieties grafted onto a single, space-saving rootstock). Double-grafted options included Sun Gold/Sweet Million and Brandywine/Grande Marzano, among others. Territorial also sold SuperNatural rootstock seeds for home gardeners wanting to try the extremely tricky art of vegetable grafting.
A grafted Rose heirloom tomato out-produces its nongrafted counterpart in a Log House Plants test garden.
The fine print
Grafting does have some limitations. While you can save seeds from grafted heirloom varieties, and the seeds will grow true, you won’t have the added benefits provided by grafting. Grafting also won’t help you with tomato hornworms and other pests. Grafted tomatoes need large pots to succeed, ideally 20-gallon or bigger, to give those vigorous grafted tomato rootstocks enough room to grow.
Finally, grafted plants are more expensive than traditionally grown tomatoes, typically about twice the cost. The reason is simple—grafting is labor-intensive. The potential payoff, however, has irresistible appeal: more tomatoes and less fuss!
If you grew grafted tomatoes this year, we want to know how they did—and how they tasted. Comment below!
Cherokee Purple is one of many popular tomato varieties now available grafted for better disease resistance.
5 growing tips for grafted tomatoes
Don’t plant them deeply: When planting grafted tomatoes, make sure the graft joint is above the soil line. If the graft is buried, the scion will root, compromising the benefits of the grafted rootstock.
Make room for roots: Because grafted tomatoes have especially robust root systems, their roots tend to reach farther and deeper than regular tomato plant roots. As a result, it’s best to plant grafted tomatoes in the ground. If you want to grow them in containers, choose a 20-gallon or larger pot.
Snap off suckers: As with traditional tomatoes, once a plant reaches about 18 inches tall, remove the suckers or shoots that emerge from between the plant’s main stem and side branches. Doing so directs more energy into the more productive parts of the plant, boosting overall harvest.
Provide support: Most grafted tomato varieties are indeterminate plants (vining tomatoes that grow and set fruit until frost) with long vines that need cages, stakes or trellises for support. Keep vines and leaves off the ground to keep the scion from rooting and to provide air circulation.
Occasionally prune: Once a plant is about 2 feet tall, remove the lowest branches and leaves to provide good air circulation at the base of the plant. Don’t be afraid to remove other branches and leaves to promote better air flow, especially as a plant grows larger and starts to sprawl. To improve fruit production, snap off suckers in between the branch crotches.
Grafted Black Krim heirloom tomato
Grafted Copia tomato
- Burpee Home Gardens
- Garden Life
- J.W. Jung Seed Co.
- Territorial Seed Co.
- Totally Tomatoes
- Vermont Bean Seed Co.
- W. Atlee Burpee & Co.
Grafted Indigo Rose tomatoes start out green. Then they turn blackish purple. They’re ripe and ready to pick when their undersides turn red.
Photos by Burpee Home Gardens, Log House Plants, Saxon Holt and Josh McCullough.