Tom Hanson, owner of Hilltop Hydroponics, a business offering year-round, local and naturally grown fresh vegetables, is a very persistent guy.

He has rebuilt one of his greenhouses at least six times when the Sonoita winds have blown it over. Hanson admits that he made some mistakes at the beginning. This first greenhouse was built facing south, so that it caught the full force of the predominantly southwest winds that blow across the Sonoita valley. His second greenhouse is oriented east and west to avoid this problem.

Hydroponics, the growing of plants in water rather than soil, was first described by Sir Francis Bacon in 1627. In the 1930s the technique was developed for commercial agricultural production. Hanson has picked up a lot of his knowledge about hydroponics by volunteering at the Center for Controlled Environment Agriculture Center at the University of Arizona.

“They get free labor, I get free education,” he said.

There are many advantages to hydroponic gardening, according to Hanson. Plants grown hydroponically use 90 percent less water than plants grown in soil because the water is recycled through the system. Hanson has lines of drain pipes, laid flat on saw horses, which have 1 ¼-inch holes drilled every foot to hold plants. Water, enriched with a nutrient solution, is run continuously through the drain pipes into a holding tank and then pumped back into the system.

“I have no concern with bacteria, I’ve got clean water and clean nutrients,” he said.

Hanson checks the pH (acidity) of the water in the holding tank daily and adds nutrient solution as needed. Although lettuce does not ordinarily perform well in hot weather, Hanson says that his hydroponic lettuce has no problem with the heat of summer here.

“The roots don’t know it’s hot,” he said, because the flowing water prevents them from getting over 70 degrees.

“I call these lazy vegetables,” Hanson said. All that they need to grow into healthy plants just flows past the roots, which are suspended in the water flow.

In one greenhouse he has more than 200 lettuce and kale plants that he harvests and sells at the Sierra Vista farmers’ market, as well as one freakishly tall pear tomato plant.

New system

Hanson starts his seeds under grow lights in his cellar in special starter plugs made of spun basalt. Once the seedlings have emerged, he plants them into net pots that fit into the holes in his drain pipe and two months later he is harvesting greens. He also grows tomatoes, peppers and European cucumber plants.

In his new, larger greenhouse, he plans to install a different type of hydroponic system where the plants will sit on floating rafts of Styrofoam in a pool of nutrient enriched water. Along the sides of the greenhouse he has begun growing larger plants, peppers, tomatoes and cucumbers, in coconut coir pots sitting in troughs and watered by drippers.

“This is not a summertime occupation,” he said.

Although he will grow lettuce, kale and tomatoes all year, his main emphasis now is greens. “In the winter I’ll focus on tomatoes and lettuce.”

Hanson has no problem selling his vegetables. “I sell out in half an hour every week,” he said.

“There is a big market that is not being served, from the restaurants to the people who live around here,” he added. “When you buy it, I picked it that day.”

“The best thing about doing this is learning every day. It is a very reasonable way to put together a system. Anyone can do it,” he noted. “And I really like the stuff I grow.”