Lettuce Harvesting Robot: Knives, Vegebot and ABB

A lettuce harvesting robot has a hard brief. It has to find a ripe head in what its builders call a sea of green leaves, cut the stem cleanly at the right height and set the head down without bruising it, and a person with a knife does all of that in under ten seconds. This post follows the job from the crews Dorothea Lange photographed in California in the 1930s, through crushed ice and vacuum cooling, to Cambridge's Vegebot and the Sami Robotics machine now on trial near Salinas. It ends with where ABB robots fit once the heads leave the field, and with the problems the machines have not solved.

A leaf lettuce harvester cuts the rows and lifts the leaves on a conveyor to workers filling crates near Yuma, Arizona, 2011. Photo: Jeff Vanuga, USDA NRCS via Wikimedia Commons (public domain)

Knives, crushed ice and big crews in California

Iceberg lettuce, the crisphead type at the centre of this story, appeared in the Burpee seed catalogue in 1894. In the early twentieth century it was grown in summer at high altitude in Colorado and Idaho and in spring in Arizona and California's Imperial Valley, and after the 1940s about 95 percent of the lettuce grown and eaten in the US was crisphead. In 2019 the Cambridge engineers who tried to automate it wrote that iceberg was still harvested with a handheld knife. The worker tilts the head, cuts the stem in one fast stroke, bags the head and puts it on a harvesting rig. Supermarkets reject a head unless 1 to 2 mm of stem is left on and the outer leaves are undamaged.

Filipino workers cutting lettuce by hand in the Salinas Valley, California, June 1935. Photo: Dorothea Lange / Library of Congress via Wikimedia Commons (public domain)

The name iceberg comes from shipping, because the heads were once packed on crushed ice for transport. Before the 1950s, lettuce was cooled with ice in packing houses away from the fields. Vacuum cooling, developed in that decade, let growers cool and pack the heads in the field instead. Both systems ran on large crews. Dorothea Lange photographed Filipino workers cutting lettuce in the Salinas Valley in June 1935, and in February 1937 she photographed a crew of 55 cutting and loading lettuce in the Imperial Valley. Her photographs show the men bent low over the rows.

A Filipino crew cutting and loading lettuce into wooden crates in the Imperial Valley, California, February 1937. Photo: Dorothea Lange / NYPL via Wikimedia Commons (CC BY-SA 4.0)

With that much hand work in the crop, labour disputes reached the shops quickly. On 17 July 1970, 6,000 drivers and packing workers in the Salinas Valley, represented by the Teamsters, went on strike and kept most of the nation's summer lettuce from reaching consumers. The Salad Bowl strike that followed, led by the United Farm Workers from 23 August 1970, became the largest farm worker strike in US history and led to California's Agricultural Labor Relations Act in 1975. Patents for iceberg harvesters go back at least to 1974 and used band saw blades or water jets. None had been shown to pick selectively in a field, and the cutters could damage outer leaves.

A farm worker carries a stack of boxes to field pickers in lettuce fields along the Colorado River, May 1972. Photo: Charles O'Rear / NARA via Wikimedia Commons (public domain)

Vegebot, Sami Robotics and the robots now in lettuce rows

A detailed attempt came from the University of Cambridge, where Simon Birrell, Josie Hughes, Julia Cai and Fumiya Iida built Vegebot. A UR10 arm on a mobile platform carried a custom end effector with a pneumatic blade, a belt drive and a soft gripper. Force feedback told the tool when it had reached the ground, so stems were cut at a steady height. Two neural networks found heads with 91 percent success. In the final trial, in a Cambridgeshire field in May 2018, Vegebot cut 31 heads. An average cycle took 31.7 seconds against under 10 for a person, mostly because the heavy tool slowed the arm, and 38 percent of the heads came off damaged.

Lettuce harvest near Ely, Cambridgeshire, in May 2012, with a harvest rig and a tractor working down the field. Photo: Hugh Venables / Wikimedia Commons (CC BY-SA 2.0)

A newer machine comes from Sami Robotics of Varennes, Québec. Its platform runs 12 to 18 arms in parallel and has already harvested commercial broccoli. Romaine is its next most advanced crop, and iceberg sits further along the roadmap. In July 2026 Western Growers gave Sami the first sponsored residency at Reservoir Farms in Salinas, and in late August KSBW reported that the harvester picks a ready vegetable in under three seconds. On 7 September Western Growers listed SAMI demonstrations in broccoli and romaine among several harvest trials. Growers are watching because of labour costs, which Western Growers puts at nearly two thirds of production costs for leafy greens and similar crops.

The cutting head of a leaf lettuce harvester working through red lettuce near Yuma, Arizona, 2011. Photo: Jeff Vanuga, USDA NRCS via Wikimedia Commons (public domain)

ABB does not build field harvesters, and we found no ABB lettuce harvesting project. Its robots already work one step later, with packed salads. Heemskerk Fresh & Easy, whose more than 400 products include fresh salads, uses ABB robots for order picking in Rijnsburg, the Netherlands. An IRB 660 places crates on a conveyor, six IRB 6700 robots on a track sort them into supermarket orders, and two more IRB 6700s build stable stacks. ABB says stores that receive crates already picked for them gain about a day of shelf life, which matters when fresh salads keep three to four days. A harvester could carry an ABB arm too, but no such machine has been announced.

An ABB robot lifts crates beside a conveyor on Heemskerk's order picking line in Rijnsburg, the Netherlands. Photo: ABB

What lettuce robots still have to learn

The Cambridge team expected the near future to look like robot arms mounted on harvesting rigs. They also saw a place for small autonomous robots that could be sent out for a sudden spike in orders, when gathering a crew and a rig would be overkill, and that could collect data between harvests. Sami describes a similar long game. The same platform could later weed, thin, fertilise and target pests, although harvesting is its only active work today. Western Growers took another route in early 2026: its staff met growers, farm workers and automation experts in Yuma, Arizona, and drafted a product requirements document for automating the iceberg harvest.

A crew and a tractor harvesting lettuce in Nobeyama, Nagano, Japan, August 2010. Photo: On-chan / Wikimedia Commons (CC BY-SA 3.0)

After the cut, lettuce moves into plants where ABB's food robots are a closer fit. The IRB 1200 Hygienic is designed for food handling, including fruit and vegetables, and can be wiped down in packaging areas or, with a protective cover, washed down in high care processing. The IRB 360 FlexPicker, which ABB calls the fastest industrial delta robot in the world, handles payloads from 1 to 8 kg. Either could pack cut leaves or whole heads, but in lettuce that is still a possibility. Cells like this are usually planned in RobotStudio first, and the bowls they feed are covered in our post on salad bowl assembly.

A wash-down version of the ABB FlexPicker delta robot being sprayed clean, as food lines require. Photo: ABB

Cost is the biggest unknown. Sami has not said whether growers will lease or buy its platform or how fast it would pay back. Western Growers says venture investment in agrifood technology has fallen by about 68 percent since 2022, so it wants to try a grower-funded, open-access model. Hygiene matters too: Vegebot was trained to leave diseased heads alone so its blade would not spread infection, and in October 2026 Taylor Farms said it would stop harvesting lettuce in central Mexico from May to August after a cyclospora outbreak. Skills change as well, since Vegebot's field tests needed one person at the laptop and another to fix physical problems. Shoppers feel any break in the harvest: during the July 1970 strike, the price of iceberg tripled overnight.

ABB robots work between stacked crates in Heemskerk's order picking hall in Rijnsburg. Photo: ABB

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