Minnesota Zoo Prairie and Butterfly Demonstration Garden Visit
June 1, 2013

“More than 18 million acres of prairie once stretched across the state of Minnesota, but today only 235,000 acres of native prairie remnants exist. As agriculture and other development spread across the state, prairie habitat was fragmented into widely scattered remnants.” (from a Minnesota Zoo Prairie Conservation graphic)

Sixteen GRC members gathered at the Minnesota Zoo for a tour of the new Prairie and Butterfly Demonstration Garden, hosted by Kim Thomas, GRC member and Minnesota Zoo Horticultural Supervisor. The tour got off to a somewhat late start due to an escaped bison, which upset normal Zoo operations. Once order was restored and our group was assembled, Kim introduced us to Sarah Braman, staff horticulturist in charge of the garden, who shared her knowledge of the prairie and this new project. 

Rather than a restored or recreated prairie, the Zoo’s project is considered a demonstration garden, which occupies the previously unattended berms surrounding the east parking lots. With funds provided by the Clean Water Land & Legacy Amendment, the garden was established in 2012 and provides a great opportunity to watch natural change in plant communities. The original prairie in Minnesota had over 300 different plant species, most of which are characterized by deep, immense root structures. About 80 percent of a prairie’s plant matter is underground. As an inspiration to homeowners, whose lawns typically contain fewer than five species, this demonstration planting is a complex ecosystem reminiscent of a shortgrass prairie, with plant materials tolerant of both wet and dry conditions. (It isn’t practical to recreate tallgrass prairie in a residential area).

There is a myth that a prairie garden requires no maintenance; many homeowners assume they can broadcast seed and a prairie garden will appear. In fact, a natural prairie can take generations to establish. Sarah estimated that it will be five to ten years before this garden will begin to be self-sustaining. The ground was initially prepared using a combination of herbicides, burning and disking before seeding with a mix of grasses and forbs. With the goal of establishing plants that can compete with weeds, the initial mix included 50-70% forbs; over time the grasses will establish and eventually reverse that ratio as the flowering plants migrate to the edges of the planting and grasses dominate the center. 

Weed control will be the major concern in the first several years, involving a lot of hand pulling, some mowing and judicious use of herbicides. Once the plantings are well established, burning will be employed as well. The biggest weed threats come from dandelions and Canada thistle, but there must be a separate management plan for each species. Pale purple coneflowers develop deep root systems and can help keep dandelions at bay; ultimately they will outcompete themselves, making room for the grasses. Other flowers that will dominate in the first few years are bee balm, black-eyed susan and asters. Grasses include little bluestem, sideoats grama and prairie dropseed. 

Most of the plant materials used in the garden were acquired from local native plant nurseries including Minnesota Native Landscapes, Inc., Prairie Restorations Inc. and Landscape Alternatives, Inc. 

The prairie demonstration garden is also going to providemuch-needed habitat for native butterflies. Dr Eric Runquist, Conservation Biologist in charge of the Zoo’s Prairie Butterfly Program, works with endangered butterfly species including the recently abundant, but now quite rare, Poweshiek Skipperling. The group had a behind-the-scenes tour of the site of the Zoo’s butterfly exhibit adjacent to the Tropics Trail. While not open to the public at the time, we were able to see, in progress, the planting of a multitude of butterfly-friendly plants in preparation of the arrival of both butterflies and visitors two weeks hence.
butterfly chrysalises await emergence
For those wishing to experience a vestige of a natural Minnesota prairie, the DNR provides a map of Scientific Natural Areas. Bird and plant lists are also available from the DNR. The nearest intact virgin prairie remnant to the Twin Cities is the Kasota Prairie near St Peter and Mankato.
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