The Tertill robot is coming to whack your weeds

Roomba’s inventors have dreamed up another robot, the Tertill auto weed whacker.

Brian Bennett Former Senior writer
Brian Bennett is a former senior writer for the home and outdoor section at CNET.
Brian Bennett
3 min read

The Tertill robot acts like a Roomba for your garden but attacks weeds not dirt.


Weeds don't quit, ever. To combat this resilient enemy you need something even more relentless and methodical. You want a robotic , unsympathetic weed-destroying device. Behold the Tertill, a robot that constantly patrols and terminates weeds in your home garden without remorse.

This $300 (£238 in the UK, roughly AU$395 in Australia) motorized weed killer is fully automatic, runs on solar power, and is weatherized to withstand the elements. In theory the Tertill never gets tired and is always on duty to attack nasty plants with its onboard weed whacker.

Search and destroy

To carry out its mission, Boston based company Franklin Robotics designed the Tertill to slowly roam garden plots or mulch beds with drone-like determination. Akin to systematic robot vacuum cleaners from Neato and iRobot, the Tertill canvasses a given area aided by software algorithms.

Two of the company's co-founders, CTO Joe Jones and mechanical engineer John Chase, are iRobot veterans. Jones lists himself as the co-creator of iRobot's iconic Roomba vacuum.

The 2.5-pound (1.1-kg) machine looks like many robovacs. A disc measuring 8.25 inches (210 mm) across, and 4.75 inches (121 mm) tall, it's flat, round, and rolls around on wheels. That's where the similarities between the Tertill and robot vacuums end. Instead of typical two-wheeled robot vacuums, the Tertill uses four. Mounted on the robot's bottom, they're all angled outward from the Tertill's center.

Franklin Robotics says the unique four-wheeled design helps widen the Tertill's center of gravity and push its support points close to its edges. As a result the robot can power through rough terrain and traverse graded slopes of up to 40 percent (22 degrees).

The splayed wheels also create room for the Tertill's primary weapon, a nylon string weed whacker on its underside. When engaged it spins a swath of destruction upon invasive foliage below.

Potential pitfalls and headaches

The Tertill's engineers admit that the robot has limitations. For instance, large rocks, holes, thick mud or other tough obstacles will stop the Tertill in its tracks. Likewise the robot can't climb inclines of more than 22 degrees.

On cloudy days with less sunlight, the Tertill won't shut down entirely but will patrol less frequently. When the sun returns and the robot can fully recharge its battery, the Tertill resumes the hunt with vigor.

I see one potential flaw with the Tertill's attack plan. The device doesn't pull weeds out from the root, but merely obliterates what's above the ground. That leaves an avenue for that same plant to reemerge. As with the Robomow robot lawnmower, you need to pen the Tertill in behind a barrier 2 inches or higher lest it wander away. The robot tells good plants from bad by wire collars you place around vegetation you like. The Tertill also requires a clean plot at first, which it will then strive to maintain. That means it can't correct a garden that's already overgrown.

Grab a Tertill for your garden

Franklin Robotics expects to ship the first batch of Tertill units to its Kickstarter backers by May 2018 for a reduced price of $250. After that the retail price will rise to $300. In the future the company plans to add other capabilities to the Tertill. These include natural pest repellents, a scarecrow function and enhanced sensors to assess soil quality and health.