Ornamental Grass Collection
One of the largest collections in the United States, the Arboretum's ornamental grass collection contains over 200 ornamental and native species and cultivars. First planted in 1987, the collection is enlarged each year, with new selections added and others removed. Maintained in 8 large beds in full sun and two beds under a lath for shade, the collection is one of the oldest in USDA Hardiness zone 4. Each cultivar or species has 4 plants, with similar cultivars planted adjacent to each other for comparison. Professor Mary Meyer, in the Department of Horticultural Science at the University of Minnesota, along with graduate students and interns at the Arboretum, evaluates these plants for winter survival, flowering time, growth habit, self-seeding, and winter interest. Also included are several materials that can be grown as alternative low maintenance turfgrasses including the native sedge, Carex pensylvanica. Download Ornamental Grasses for Sustainable Landscapes brochure.
The Arboretum Ornamental Grass Collection is one of the largest in the United States, and ranges in size from 5-6 inches (Festuca glauca) to 15 feet (Miscanthus x giganteus), with colors of blue, yellow, striped and green with a wide variety of textures.
The grass collection is near the Maze about 2/3 of the way along Three-Mile Drive at the Arboretum. In the spring, usually in April, the collection is burned to remove the previous year's growth. The burning actually invigorates the grasses by removing old stems and leaves, opening up the crown or growing point to sunlight and rain. The grasses quickly grow with summer rain and warm temperatures. In late summer and fall, miscanthus, switchgrass, moorgrass, Indian grass and many others flower and are at their peak of interest , many being several feet tall. In winter the grasses stand tall in the snow, providing cover and food for birds and wildlife. Viewing the Arboretum grass collection is rewarding throughout the year.
Of the eight beds in sun, Bed Number 1 contains the Molinia (moorgrass) collection and has space for annual grasses and is planted with new "bedding plant" grasses sold in garden centers each spring for planting as annuals. Several of these are bold in colors, purple, red and have showy flowers that work well with other annuals, such as petunias or foliage plants including sweet potato vines.
‘Prince' elephant grass is a showy dark purple and grows quickly in hot, summer weather, but dies with the first frost.
The Molinia collection in Bed #1 contains 7 species or cultivars of moorgrass.
Bed #2 is the cool season grass collection with sun sedges, feather reedgrass, blue fescues, blue oatgrass and tufted hairgrass. This group likes cool weather and starts to grow early in the spring. These grasses flower in May and June, becoming brown by fall. This two-toned look, brown seedheads and green leaves at the base, is attractive and showy for most of the year.
The Calamagrostis collection is a favorite of gardeners. Flowering in spring and with a wheat-like look in summer and fall, this tough grass is very hardy in Minnesota.
Bed #3 contains the tallest grass: Miscanthus x giganteus or Giant Miscanthus, a grass of great interest for biomass fuel source. Growing over 10' tall each year, this tough perennial is a delight for children, who hide in it every summer. Also in this location are several sun sedges.
Giant Miscanthus grows each year to over 10' tall in Minnesota.
Bed #4 contains native grasses, including slough or cordgrass, Spartina; Indian grass, blue grama and sideoats grama, sweetgrass and little bluestem. The new patented grass Blue HeavenTM, a new upright and colorful form of little bluestem from the U of M, is also planted in Bed #4.
Blue HeavenTM little bluestem is about 4‘ tall and blue in summer, burgundy and red in the fall.
Bed #5 contains many cultivars of switchgrass, including ‘Northwind', ‘Dallas Blues', ‘Shenandoah', ‘Prairie Sky', ‘Cloud 9', ‘Thunder Cloud', planted for comparison. An Indian grass collection being evaluated with the NRCS Plant Materials Center in Bismarck, ND and Miscanthus sinensis ‘Zebrinus' are also in this bed.
Switchgrass is native to most of the United States. From left, Cloud 9, Prairie Sky, Dallas Blues, and Shenandoah are cultivars of this tough native grass.
Bed 6 &7 contain many cultivars and species of Miscanthus, one of the showiest and most popular ornamental grasses. Native to Japan and the Far East, miscanthus is hardy in Minnesota, although plants may die back in severe winters. These tall showy grasses are most attractive in September when they flower.
Little Fountain (left) and Sirene are two miscanthus grown at the Arboretum.
Bed 8 contains the striped miscanthus and a collection of tufted hairgrass, Deschampsia caespitosa that is being evaluated for outstanding, new ornamental forms.
Under the lath, near the overlook to the Arboretum azalea collection, are many sedges and grasses that prefer shade. Hakone grass is here, one plant that was planted in 1987. ‘Aureola' hakone grass is the Perennial Plant of 2009, selected by the Perennial Plant Association.
Sedges are good choices for landscape plants but information on hardiness and growth habit is needed for growers to select the best plants for Minnesota gardens.
The Ornamental Grass Collection is a great asset to the Arboretum, growers and gardeners in the upper Midwest. Without the University and Arboretum evaluation of these plants, many would not be grown and sold by garden centers since their landscape characteristics are unknown for zone 4. Growers are very skeptical of growing plants with unknown hardiness information in Minnesota. The work from the Arboretum has resulted in the publication of several research articles and the public informational bulletin Ornamental Grasses for Cold Climates, by Mary H. Meyer, University of Minnesota Extension. Seeing the plants grow in natural conditions is important for gardeners and commercial growers.
Information is also needed on landscape plants that require few inputs, including reduced water or fertilizer, and the grasses fit this niche very well. We use very little water and fertilizer on the Arboretum collection. Grasses survive drought and do not need supplemental fertilizer to grow their best each year. Information on attractive native plants is essential for new and wise choices for landscape plants for sustainable landscapes.
The Ornamental Grass Collection provides a place of beauty and peace at the Arboretum. Enclosed by a tall lilac hedge, the collection is a haven for reflection -- watching birds and wildlife while listening to the quiet susurration (whisper of the wind) in the grasses. This location is a favorite of many Arboretum visitors.