It's not only the plants that are growing at the University of Minnesota Landscape Arboretum.

As it begins its 55th year, the public garden and research center in Chanhassen has big ambitions: the purchase of a $4.4 million piece of property to its north, the grand opening of a world-class sculpture garden, and a new hookup to bike trails that will permit two-wheeled visitors.

It's all part of a master plan to upgrade the arboretum's gardens and buildings, add new permanent attractions, and expand educational and research programs.

Acquiring 78 more acres will provide a "buffer zone" to help preserve the arboretum's natural features in a rapidly developing part of the west metro, Director Ed Schneider said in a recent interview.

Along with new windows, roof and other improvements to the 1970 Snyder Building, Schneider said the arboretum had many successes in 2012, and a few surprises. Attendance took a bigger hit than expected in summer because of road construction, and unusual spring weather nicked the apple orchards. It was also a year in which individual entrance fees rose from $9 to $12.

Schneider discussed the year past and the year to come in a recent interview.

What can people expect with the new sculpture garden?

It will have 22 works of art, and most of the sculptures have already been delivered and installed, Schneider said. It will feature large-scale artistic works from several countries, including American artists Louise Nevelson, Paul Granlund and Jesus Moroles.

The three-acre garden will not be open until midsummer, after landscaping has been completed.

Schneider said all of the art comes as a single donation to the University from philanthropists Alfred and Ingrid Lenz Harrison of Wayzata. The gift includes all costs to transport the sculptures, build concrete footings and pedestals, and landscape the area, plus establishing an endowment, he said.

"It's a tremendous addition, and there's a lot of excitement already about it," he said.

The sculptures are clustered on a high point within the arboretum, and three more will be added in future years.

What else will be new in 2013?

The arboretum will add a free people mover, or tram, that will circulate along Three Mile Drive and allow passengers to get on and off at three different locations.

"It's designed to encourage people to get out of their cars, and stop and walk the trails to get close to plants," said Schneider.

The tram will be solar-powered, he said, and will hold about 22 people. He hopes to have two of them running continually along the drive. It will not replace a separate, larger tram that offers visitors a nonstop, narrated tour for a fee.

Also new will be "Gophers in the Garden," a temporary exhibit that will feature four-foot molded versions of the U's mascot that will be decorated and placed throughout the grounds.

How was 2012 in terms of attendance, since you raised individual entrance fees last spring from $9 to $12?

There were few complaints about the price increase, Schneider said, and attendance of 329,000 (July 2011-June 2012) was about 4,600 less than the previous year. Memberships also gained modestly, he said, rising to nearly 23,000.

However, attendance hit a snag during summer, he said, because of major construction along Hwy. 5 that fronts the main entrance to the arboretum. Although MnDOT kept the road open to the arboretum, a lot of people avoided the area.

"We saw a pretty precipitous drop," said Schneider, about 10 percent below normal in June, July and August. "We did not forecast the decline in visitation to the degree we experienced."

But the arboretum was more popular than ever this fall, he said, and attendance numbers bounced back as weekends and special events attracted thousands.

Are you still trying to purchase any land along the fringes of the arboretum?

"One of the things we're very hopeful for in 2013 is acquisition of a piece of property that's 78 acres, on the north side of Hwy. 5 and contiguous to our apple orchards," Schneider said.

The land contains part of Tamarack Lake, wetlands and a portion of big woods forest.

The property was appraised at $4.4 million, and the arboretum hopes to raise enough from public sources and private donations to purchase the land next summer.

How would people access that land?

The Hwy. 5 reconstruction added a pedestrian and bike trail underpass so that bikers no longer need to ride along the highway shoulder to reach the arboretum.

"We're gearing up for all the bicycle visitation," Schneider said.

The arboretum will be linked to the regional trail system, he said, and riders will be able to ride through the arboretum for free, or pay a fee if they're going to stop and visit the garden displays, restaurant, gift shop or other attractions.

What's been happening with your scientific mission?

In late 2011, the arboretum became affiliated with the Center for Plant Conservation, a national nonprofit based in St. Louis and dedicated to protecting and restoring imperiled plants.

The arboretum is monitoring 16 plants on the federal endangered species list that grow in Minnesota, western Wisconsin, the eastern Dakotas or northern Iowa.

Scientists will study places where the endangered plants still live and determine whether they are in jeopardy, collect seeds in a seed bank to protect the species, and study whether their populations decrease over time.

Breeding cold-hardy new varieties of apples, grapes and other fruit continues at the arboretum's Horticultural Research Center, Schneider said. And despite a cold snap last spring that killed apple blossoms and decimated some orchards, he said the arboretum's apple harvest was near normal: down about 15 percent.

Tom Meersman • 612-673-7388