If you have trouble keeping an indoor vegetable garden alive, it’s possible to drop $200 on a sensor-filled indoor greenhouse that will do the watering for you. Now there’s a low-tech version of the same thing: A new self-watering pot uses clay and a technique that’s been around for 4,000 years.

“There’s two main issues of growing food that make it hard–light and water,” says Nikhil Arora, co-founder of Back to the Roots, an Oakland-based startup. “The water part is really where it gets tricky. How much do I water? When do I water? I’m going on vacation for a few days, and what’s going to happen to my plants? … We realized the trickiest thing in growing food is solving this water issue, and creating a self-watering system for plants.”

The self-watering planter, designed to grow cherry tomatoes, is based on ollas, low-fired clay pots that have been used in arid parts of North Africa for thousands of years. “The water only seeps out of the olla as the roots take up and dry out the soil,” says Arora. “So it’s automatically irrigating as the plants need water. You’re not going to drown the roots or keep them too dry.”

Back to the Roots took the concept of the olla, shrunk it down, put it in a mason jar filled with a rich soil amendment called biochar, and is now selling it as a windowsill tomato-growing kit. “It’s an opportunity to connect people back to food,” he says. “And do it not through apps or microsensors.”

It’s an opportunity to connect people back to food.

In the world of Bay Area food startups, the company sees itself as pushing against some of the trends. As some food gets more complicated–like plant-based eggs or lab-grown beef–Back to the Roots’ philosophy is to find the simplest traditional way to grow food, and repackage it for millennials who may have never gardened before. The company is also starting to make ultra-simple packaged food.

“You see hundreds of millions of dollars from tech folk going into this new wave of food,” says Arora. “They’re saying we’re going to reinvent the future of food, and it’s all laboratory based and high science … we want to go back to food made in a kitchen, not a lab. Our R&D team on our website is not food scientists, it’s our whole teams’ grandparents. How do you take that energy and make it accessible to a new generation?”

The company’s beginning was an unlikely one; Arora and co-founder Alex Velez were college seniors planning to go into finance when they happened to learn that mushrooms could grow on coffee grounds. “We kind of fell in love with that idea our last semester, and we went from investment banking to urban mushroom farming,” Arora says. Soon, they were making tiny mushroom farming kits; a year later they were selling them at farmers markets, and they were on the shelves at Whole Foods.