Let’s say you want to grow stuff — flowers, shrubs, cacti, fruit or edible plants. But you need some ideas.

What to plant? What might grow well in your yard or garden? How can you best nurture the plants you plant?

One place to learn a lot is the Pima County Master Gardener Demonstration Gardens at 4210 N. Campbell Ave.

With 14 themed gardens ranging from “Cacti and Succulents” to “Raised Bed Edibles,” the free site offers a view of plants well placed and information about them.

“The point of the demonstration gardens is for people to come and see what we’re doing, knowing that the practices used here are based on university research in horticulture,” said Eric Johnson, coordinator of the Pima County Master Gardener Program.

“We believe we use best practices based on scientific research,” Johnson said. “People can see what we do and what it looks like. If it works well here, it’s probably going to do well at your house.”

Johnson said the gardens are “open like a city park — open and free during daylight hours.”

VARIETY OF GARDENS

Among the demonstration gardens are ones devoted to cacti and succulents, roses, raised-bed edibles, colors, pollinators, native grasses and others.

“We have added a new feature to the gardens this year — an aquaponics demonstration located within the Color Garden,” Johnson said. “It’s a closed system that uses fish to fertilize plants. The plants then remove the ammonia and essentially clean the water for the fish. It’s a balanced symbiotic relationship.”

In a garden with trees grows an Anna Apple, a fruit tree for mild winter climates — developed in Israel and bearing abundant fruit this month.

Another area displays a “three sisters” planting.

“Three sisters planting,” a sign explains, “is a traditional way of planting staple food crops by the Iroquois Tribe and many other Native American people.

When planted together, the three sisters of corn, beans and squash complement each other’s growth habitats and provide a remarkably healthy diet.”

Tall corn stalks provide poles for the beans to climb. Beans pull nitrogen from the air — benefiting the corn, which needs a lot of nitrogen. Sprawling vines of squash shade the roots of its sister plants, helping to cool them and lower water demands.

PLANT CLINIC AND TOURS

Visitors who want to learn more about plants and planting can take advantage of a plant clinic in the main building at the site. It’s open from 8:30 a.m. to 4:30 p.m. Mondays through Fridays.

It’s staffed by a master gardener, one of about 180 certified master gardeners who take part in the county’s program, Johnson said.

He said free tours of the 40,000-square-foot demonstration gardens area are held at 9 a.m. Saturdays and Wednesdays.

“Just show up and we’ll walk you through it,” Johnson said.

“The tours last an hour or a little more.”

Contact reporter Doug Kreutz at dkreutz@tucson.com or at 573-4192. On Twitter: @DouglasKreutz