Sometimes a model railroad meant to run outdoors can take over a yard. Track, trestles, tunnels, town buildings and other features become the overwhelming focus.

Glenn and Janet Mitchell's G-gauge (for "garden") setup demonstrates a balance between landscape and layout.

Theirs is one of 10 stops in the annual Rails in the Garden self-guided tour that the Tucson Garden Railway Society is hosting next weekend.

The couple landscaped their backyard from scratch when they moved into the west-side home 20 years ago. They took out a putting green and built raised beds and planters smartly finished with pavers, bricks and landscape rock. They topped the soil with decomposed granite to control erosion.

Glenn, an electrical engineer by training and career, drew up plans that included 650 feet of track, bridges, tunnels, underground wiring and automatic irrigation.

There's plenty of room for buildings along the track, but also for vegetation.

"We knew we wanted a few plants," Glenn says. But they did need to spend time figuring out what works best. "We do the trial-and-error method," he says.

Plants that they've settled on are pretty compact. "We look for things that are small and not too messy," Janet says. That includes plants with small leaves.

Non-fruiting dwarf olive and dwarf pomegranate, as well as dwarf bottlebrush, fit the bill, growing slowly into the scale of giant shade trees for the turn-into-the-20th-century theme of the vignettes.

Other usable plants for their lay-out have to survive some severe pruning.

Janet trims trailing rosemary bushes into bonsailike trees, revealing gnarly "trunks" and branches topped with blue-blossomed canopies. They serve as stands of trees that line the mountainous route of the steam locomotives.

She concedes that the railroad wins out every time in the gardening war. Any vegetation that grows across the tracks gets pulled out or pruned back.

Not every planting is meant to work with the layout. Small patches of angelita daisies and petunias take up space just because they're pretty. A mature palo verde and a black acacia aren't kept to the railroad's scale.

"We consider both the railroad, which is nice to have, and a little shade," Janet says. "We like to have a few trees."

If you go

2013 Rails in the Garden

• What: Self-guided tour of 10 garden railroads.

• When: 10 a.m.-4 p.m. Saturday and next Sunday.

• Where: Homes generally west and north of central Tucson and the Gadsden-Pacific Division Toy Train Operating Museum.

• Admission: $5, free for younger than 18 years when accompanied by paid adult. Tickets available at toy train museum, Rillito Nursery & Garden Center, Southern Arizona Transportation Museum and Hobby Place at Ace.

• Information: 488-4461 or

Contact Tucson freelance writer Elena Acoba at