Alternative vegetable gardening, a tribute to former U.S. Rep. Gabrielle Giffords, and gardening classes are among the features of three tours in the next two weekends.

Tucson Aquaponics Systems Tour

This tour provides a look at systems that combine growing plants in water, known as hydroponics, with raising fish, called aquaculture.

Fish droppings add ammonia in the water that fertilizes the plants. By drawing out the ammonia, the plants filter the water for the fish.

Stops will demonstrate systems ranging from beginners' "barrelponics" to commercial production systems, says organizer Stéphane Herbert-Fort, owner of Local Roots Aquaponics.

"Having even a small kitchen-garden system running at home can be a joy for the whole family," Herbert-Fort says in an email message.

Tucson Open Days

Three Tucson gardens are among more than 300 in 19 states that are part of this year's Open Days Program, a benefit for the national Garden Conservancy.

Landscape designer Elizabeth Przygoda-Montgomery, owner of Boxhill Design, organized the Tucson tour.

It includes the private and community gardens of Brad Holland. He is growing some of the plants that were left at spontaneous memorials to the Jan. 8, 2011, shooting victims, including Giffords.

He was part of the team that collected, cataloged and packed up the items that people left at three locations.

Also on the tour is the xeriscape of landscape designer Jason Isenberg, owner of Realm, and a native garden and outdoor living space that Przygoda-Montgomery designed.

Master Gardeners Garden Tour

Gardening educators trained by the Pima County Cooperative Extension match gardens on the tour with classes to help visitors replicate what they see.

The hourly sessions at each stop - the home of a master gardener - will focus on vegetable gardens, container gardens, irrigation systems or fruit trees.

Master gardeners will answer questions at the extension's demonstration gardens, which are part of the tour.

IF YOU GO

Tucson Aquaponic Systems Tour

• What: Self-guided tour of at least seven sites.

• When: 9 a.m.-3 p.m. Saturday.

• Where: Throughout Tucson.

• Cost: Free. A $5 donation is suggested.

• Information: 1-765-276-6427, localrootsaquaponics.com

Tucson Open Days

• What: Self-guided tour of three home gardens.

• When: Saturday. Two are open 10 a.m.-4 p.m.; the third 10 a.m.-2 p.m.

• Where: 1933 N. Bell Ave. and 1340 E. 14th St. until 4 p.m. Directions to the third are available at the other two gardens.

• Cost: $5 per garden. Tickets are available at Tohono Chul Park, L'Atelier de la Fleur and tour sites.

• Information: 1-888-842-2442, opendaysprogram.org

Master Gardener Garden Tour

• What: Self-guided tour of four homes and the Pima County Cooperative Extension's demonstration gardens. Mini-classes are at each location.

• When: 9 a.m.-3 p.m. Oct. 13.

• Where: North and northwest sides of Tucson. Extension gardens are at 4210 N. Campbell Ave.

• Cost: $10, $30 for four tickets; free for children younger than 12. Tickets with maps are available at the extension, Green Things nursery, Harlow Gardens and Rillito Nursery & Garden Center.

• Information: 626-5161.

Contact local freelance writer Elena Acoba at acoba@dakotacom.net