The Minnesota Landscape Arboretum on Tuesday announced the kickoff of the public portion of a $60 million capital campaign, the most ambitious fundraising effort in its 56-year history.

The arboretum — the largest public garden in the Upper Midwest — already has raised almost $45 million from private donors, including one $6 million gift for expanding a conservatory. About 328,000 visits were made to the Chanhassen public garden and education and research center in the year ended June 30.

Now the final stretch of the five-year fundraising campaign begins for the remaining $15 million. In addition to the conservatory, the long list of projects planned includes a Chinese garden walk and a "discovery center" dedicated to teaching the public the importance of preserving bees and other natural pollinators.

"We want to create a world-class arboretum for the citizens of Minnesota, keeping it the wonderful place that it already is," said Ed Schneider, arboretum director and professor at the University of Minnesota.

Last week, private donors attended an event at the arboretum to learn details of projects that have already been completed and others still in the works. "We're hoping they'll serve as good ambassadors who will help spread the word to get the whole community involved in enhancing the arboretum," Schneider said.

The idea for creating the bee and pollinator center began about four years ago with Marla Spivak, one of the university's top bee researchers, said Judy Hohmann, the arboretum's marketing and communications manager. Spivak told the arboretum she was interested in establishing a community outreach facility. About the same time, the family of Joe Tashjian, a St. Paul radiologist, expressed interest in such a project. Hohmann said the family knew Spivak and had learned about her research.

"The stars really aligned, as public awareness of this issue grew and the gift [of $2 million] from the Tashjian family made the goal for a center more tangible," Hohmann said. About $6.4 million has already been raised for the $6.9 million center, Schneider said. The facility will house exhibits on pollinators and programs on bees' social behavior as well as the health benefits of bee products.

The bee and pollinator center will be next to the arboretum's Red Barn, which is being used for storage. Money from the capital campaign is being used to transform it into a sustainable farming and landscaping learning hub with interactive exhibits and displays. Some money also will go toward a new multi-use roadway that will branch out from the arboretum's Three-Mile Drive and connect the Red Barn and the bee and pollinator center with other arboretum buildings and gardens.

Work has also begun on the walk for a future Chinese garden whose features will include a wetland pond, weeping willows, peonies, day lilies and other plantings of Asian origin.

The $6 million donation for expanding the Meyer-Deats Conservatory came from Armand Brachman, a comanaging partner of Dominium Co., a Twin Cities affordable housing and property management firm. Schneider said the expansion will allow the building to become a year-round facility with plant displays in various climate ecosystems.

Several features of the capital campaign have already been completed, including the Harrison Sculpture Garden, the Wurtele Bog Walk, renovations to the Woodland Azalea Garden and Waterfall, a plaza and gatehouse at the arboretum entrance, and new visitor rest stops.

Hohmann said the arboretum hopes to wrap up the fundraising campaign, which began in 2011, by fall 2016. Donors can target their gifts to specific projects on the arboretum's website or in donation boxes at the gardens.