When Kate Netwal wants a fresh, crisp salad, she doesn't have to go to the grocery store. She makes one from the greens growing in her Minnetonka closet.

Yes, her closet. That's where Netwal has two 10-gallon tubs under grow lights in which she grows lettuces and other veggies hydroponically, in water, even in the dead of winter.

"I love it! It's really easy. This is my fourth year," said the Master Gardener, who also grows veggies outdoors during Minnesota's gardening season.

"I've always been interested in ways to grow food year-round," Netwal said. Recent romaine salmonella outbreaks and now grocery shopping in the pandemic era have made her even more interested in growing some of her own produce. And with hydroponic gardening, she can do it even when it's too cold to garden outside. "It's so wonderful to have fresh vegetables."

Netwal learned hydroponic gardening from her mentor in the Hennepin County Master Gardener program, Larry Cipolla, author of "Hydroponic Gardening the Very Easy Way" (available at Amazon, $23.70), who has been teaching the method at schools, garden clubs, senior centers and conferences.

Cipolla, who grew up on a small farm in Connecticut, gardens in soil at his Edina home but also grows herbs, greens and other vegetables in water-filled containers in his basement from Labor Day to May, when he brings many of his plants outside.

"I harvest almost every evening," he said. "Most nights we eat something we grew."

Hydroponic gardening offers many advantages, especially for those in cold climates, he said.

"You can garden year-round. That's a huge plus up here."

It's also more sustainable than growing in soil because it requires less water and less fertilizer, he said. "And there's no runoff in lakes, ponds or drinking water." Also heavy rains can cause fertilizer to leach out of soil, he noted. "With hydroponics, you don't have the issue."

Ancient roots

Hydroponic growing is an ancient practice that dates back to the Hanging Gardens of Babylon, built in 600 B.C. Cipolla, a management consultant, first encountered hydroponics during a trip to Singapore in the mid-'90s, and his interest grew during subsequent visits there.

"I became fascinated by it," he said. He marveled at the sight of tomato plants growing and thriving 4 inches apart. "That's the thing with water. The roots grow vertically vs. spreading out. The roots don't have to look for food. It's there. So they can grow in a small space."

Hydroponic gardening is ideal for people who don't have a lot of space for soil-based gardening or who have poor soil quality, as well as for seniors and others who don't want to deal with bugs or humidity, he added.

Cipolla's book and his teaching focus on the passive deep-water culture system, which is the easiest to set up, he said. It's basically a form of container gardening. All that's required are plastic buckets sold at home-supply stores, baskets or net cups, a growing medium to support the plant structure (Cipolla advocates a mix of peat and perlite), hydroponic fertilizer and grow lights.

His book includes step-by-step DIY instructions, including suggestions for inexpensive supply sources. Startup costs can range from about $100 to $250; Netwal, who already owned grow lights, estimated that she spent about $70 to set up her hydroponic system.

Hydroponic gardeners can start plants from seed or "cheat" with store-bought plants, both of which are addressed in the book.

Some crops work better than others for hydroponic growing. Herbs and greens are good candidates. When he works with schools, Cipolla usually starts with quick-germination crops, such as lettuce, he said.

"You can grow so many different kinds of lettuce," said Netwal. Her favorite is Crispino, an iceberg variety. "It forms little heads, a little bigger than a fist. A perfect amount of lettuce."

She prefers hydroponic lettuce to soil-grown lettuce. "What I like is the greens are so clean. With greens grown in the ground you have to rinse and rinse."

She's had mixed success with other crops.

"I did try peppers from seeds. But I don't think it was warm enough" — her growing closet is against an outside wall. "I experimented with some beets, and I actually did get a little beet," she said. "It's fun to experiment."

Many other vegetables, including tomatoes, peppers and beans, also can be grown hydroponically, according to Cipolla, whose book includes detailed directions for various crops, including optimal container size.

School-grown greens

Breck School in Golden Valley has been putting hydroponic gardening to the test in a corner of the school's common area.

"Last year they set up a hydroponic system with the help of Larry [Cipolla]," said Kati Kragtorp, a biology teacher who advises the school's Food Justice service-learning group. The goal was to grow fresh food and donate it to a food shelf.

"I was blown away by how easy it was," Kragtorp said. "It's a simple system — Rubbermaid bins with holes cut in the top, nets, water and liquid fertilizer. You get it started, and it's very low-maintenance. The students had so much fun with it."

Breck students grew lettuces and herbs, which they harvested and donated to the PRISM food shelf in Golden Valley, Kragtorp said. "It's a great way to get fresh food in the middle of winter. The food shelf was happy to get something green when all they had was potatoes and root vegetables."

Kragtorp polled her students on what they wanted to grow next, and they said strawberries. Those required starting with plants rather than seeds, and spider mites came along with them, she said. "We got some fabulous strawberries, but it was not as productive as we hoped."

Breck's hydroponic garden is dormant now that schools have closed due to the pandemic. But Kragtorp plans to resume growing once the school reopens. "Absolutely, we will do it again," she said. "Now that we know what we're doing, we'll hit the ground running."

Working with the students has inspired her to think about hydroponic gardening at home.

"I was totally converted," she said. "I absolutely want to have one. I couldn't get over how easy it is. You don't have to worry about weeds or about insects or rabbits eating it. It's fun to weed, but it never ends."

Netwal converted her son, who recently moved to Rochester.

"He's got a system in his closet, too," she said. "I'm so sold on the idea. I think everyone should have one."

Kim Palmer • 612-673-4784