Tomato grafting has long been part of the controlled-environment agriculture conversation, but it rarely sits at the center of debate. That’s changing as growers face mounting disease pressure, labor constraints and rising production costs, all while also demanding longer crop cycles and more consistent yields.
Those issues were discussed during Indoor Ag Conversations Presents: Tomato Grafting — Where It Delivers, Where It Doesn’t, and What’s Changed, a Jan. 13 webinar moderated by Matt Korpan, executive director of research and innovation at BiopHi.
Panelists included Hande Saganak, vegetable grafting operation and research and development leader of The Morning Star Company, and Ben Pieterse of TTA-ISO, an automation solutions company.
What Hasn’t Changed
The plant still sets the rules.
Despite advances in rootstock breeding and propagation technology, Saganak says tomato genetics, and basic plant physiology, still dictate outcomes.
“Tomatoes still need a certain amount of nitrogen, light, humidity and heat,” she says. “You can’t bypass that with grafting.”
What has changed is uniformity. In the early 2000s, Saganak recalled working with rootstocks that varied widely in stem diameter, complicating grafting success. Today, improved breeding and propagation practices have made it easier to match scions and rootstocks, one of the most critical factors in successful grafting, she says.
“Matching diameter is one of the most important parts,” Sagaak says. “We adjust growing techniques specifically, so rootstock and scion align at the right time.”
The panelists repeatedly returned to one theme: Grafting is essentially plant surgery, and hygiene failures can wipe out thousands of plants quickly.
After grafting, young tomato plants are left with open wounds that require high humidity and careful environmental control to heal. That same environment also creates ideal conditions for disease if sanitation slips.
“Hygiene, disinfection and sanitation are among the most important factors,” Saganak says. “Anything that touches the plants can introduce disease.”
That includes shoes, tools, hands and even food brought into the greenhouse. Panelists noted many operations now rely on strict zoning protocols, disinfectant footbaths, protective clothing and air and water sanitation systems to reduce risk.
Korpan says propagators, particularly in North America and Europe, have raised the bar in recent years, driven by grower expectations and the high cost of crop failure.
“Growers want to know the plants are coming in clean,” he says. “They’ve already invested heavily in sanitation before those plants ever arrive.”
Automation Shifts the Economics
Labor remains the biggest cost barrier to grafting, particularly for processing tomatoes and outdoor production. That’s where automation is changing the equation.
Pieterse says automated grafting machines are allowing nurseries to reduce labor needs dramatically while improving consistency.
“A machine does the same thing every time,” he says. “People are flexible, but they’re not consistent over long periods, and grafting demands consistency.”
At Morning Star, automated grafting has reduced labor requirements from nine workers to roughly one or two per line, Saganak says. While automation doesn’t eliminate overseeding or plant losses, she says it improves predictability and makes grafting more feasible at scale.
Sorting technology is another key lever. Removing weak or non-germinated plants early saves greenhouse space, energy and labor — critical in high-input CEA systems.
“If you can sort early, you stop wasting resources on plants that won’t make it,” Pieterse says.
When Grafting Makes Sense and When it Doesn’t
Not every grower grafts, and the panelists were clear that grafting isn’t a universal solution.
For high-tech greenhouse tomatoes, grafting often delivers value by extending crop life to 10 to 12 months or longer, improving resistance to diseases such as tomato brown rugose fruit virus, and supporting plant vigor through high-stress periods like summer heat.
In lower-tech systems, or in greenhouses intentionally running short crop cycles, grafting might not pencil out. Some growers opt for fast, non-grafted crops when energy prices spike or disease pressure makes long-term production risky.
“There has to be a payoff,” Korpan says. “If you don’t need the plant to last a full season, grafting may not make sense.”
While the webinar focused on indoor and controlled environments, interest in grafting is expanding into field production, particularly where soil-borne diseases, broomrape or declining soil health limit yields.
Saganak says trials in processing tomatoes have shown 25% to 30% higher yields with grafted plants, even at lower planting densities, though cost remains the primary hurdle.
“Automation is what makes that possible,” she says. “Without it, the labor cost is too high.”
A Tool, Not a Shortcut
Ultimately, the panelists framed grafting as a precision tool rather than a silver bullet. Success depends on matching rootstock and scion to production goals, whether that’s longevity, disease resistance, fruit quality or speed to harvest.
“Rootstock choice reflects priorities,” Saganak says. “Strength, taste, short-term versus long-term production, you have to decide what matters most.”
