Cutting Edge | Magazine

The roboweeder aims to do for gardens what Roomba does for floors

A new robot from Billerica-based Franklin Robotics tackles gardeners’ least favorite job: weeding.

A Tertill in its habitat. The name references both a slow-but-steady animal and the idea of tilling the earth (terra in Latin).
The Tertill moves slowly, like its soundalike namesake, and keeps just as strong a grip on terra firma.

Pretty much no gardener likes the thankless, back-straining chore of weeding. Enter the Tertill, which might be described as a Roomba for weeds.

Like iRobot’s popular robot vacuum, the Tertill, being developed by two-year-old Billerica startup Franklin Robotics, is circular and goes around cleaning up. But it’s waterproof, so it can live outdoors, and it’s solar-powered, so you don’t have to remember to plug it in. And of course, while the Roomba eats dust, the Tertill, like its slow-and-steady eponym, eats weeds. Or rather, the 8.25-inch-diameter device — about the size of a dessert plate — bumps around gardens looking for plants an inch or less in height, then cuts them down to a quarter-inch in height with the same spinning nylon line setup as a typical weed whacker.

All gardeners know that to keep weeds from coming back, you must pull them out by the roots. But many weeds stop growing after they lose their leaves, notes Franklin Robotics CEO Rory MacKean. And because the Tertill can patrol a garden regularly, it can keep cutting young weeds down to size, discouraging most of them from returning.


It’s true, MacKean says, that “Tertill won’t get all your weeds.” But he points out that neither do most gardeners.

MacKean started Franklin Robotics in October 2015 with Joe Jones, who was the first full-time hire at iRobot and is named on more than 60 of his former employer’s patents. They’ve spent the last 20 months creating their robot. The biggest challenges involved keeping it from getting stuck and from damaging plants. Two types of sensors keep the Tertill on the job. One detects obstacles, like rocks, and prompts it to change direction. The other uses the same touch-sensitive technology as smartphones. These sensors, on its front and bottom, gauge plant heights, and for those shorter than an inch activate the cutting mechanism. The Tertill comes with plant collars gardeners can put around their seedlings to protect them.

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Owners use a smartphone app to check Tertill’s status and handle software updates. Other than Tertill’s on/off switch, it’s autonomous, not that it won’t need a helping human hand occasionally. “If there’s a hole, you fill it in. If there’s a rock, you throw it out of the garden,” says Jones. Gardens also need a fence or other border, so the Tertill doesn’t wander off.

The device is still a prototype. However, the company is far enough along that the product launched recently on Kickstarter for $249 (it will sell for $299 in stores). It expects to start shipping Tertills in spring 2018.

Will gardeners drop their stirrup hoes, toss aside their fishtail weeders, and buy the device? Garden consultant and designer Elizabeth Pope of West Newbury says it is difficult to imagine using one in gardens crowded with emerging perennials. But the potential market is vast. Baby boomers are the biggest spenders on gardening, and as they age, may tire of stooping to conquer the weeds in their gardens. Meanwhile, technology-friendly millennials are the fastest-growing gardening market.


Despite its name, the Tertill appears likely to be faster to market than potential competitors, such as the Weedobot, which has no firm delivery date. The finish line is still a ways off, but Tertill could reduce weeding to about the same level of dread  as loading the dishwasher.



> 8.25 inches in diameter

> 4.75 inches tall

> 2.5 pounds


> Battery lasts 60-90 minutes, good for weeding at least 100 square feet of garden.

> Includes a USB slot for backup charging.

John Dodge is a freelance journalist, and gardener, in West Newbury. Send comments to Follow us on Twitter @BostonGlobeMag.