Ornamental Grass Field Trials and Evaluations

Evaluations of native and ornamental grasses for field stress tolerance are being conducted in Minnesota. A large collection of 167 grasses, sedges and rushes was planted at the Minnesota Landscape Arboretum in 1987. Winter survival, flowering time, self-seeding and suitability for landscape use in USDA Zone 4 was published after six years of evaluations.
Ornamental Grasses for Cold Climates, by M.H.Meyer, D.B.White and H. Pellett, published in 1995 reports the results of these trials and is available from the University of Minnesota Extension Service, 1-800-876-8636; www.extension.umn.edu.

Additional species and cultivars have been added annually to the original collection, including approximately 40 different Miscanthus. In 1996 a collection of 30 of the more popular and hardy grasses were planted at the West Central Research and Outreach Center in Morris, MN and at the Northwest Research and Outreach Center in Crookston, MN. These plants are evaluated for similar characteristics and compared to the Arboretum planting. Several years of data will be taken at the Morris and Crookston sites and subsequently published. For more information contact www.extension.umn.edu or meyer023@umn.edu.

Miscanthus Anderss. Produces Viable Seed Across Four USDA Hardiness Zones

Forty-one taxa of Miscanthus grown in USDA Hardiness Zones 4, 5, 6, and 7 were examined for two years for seed set and viability. Although the laboratory results varied widely between years, climatic zones, and cultivar, most plants set viable seed. The later-flowering types, such as 'Gracillimus', 'Morning Light', 'Variegatus' and 'Zebrinus' appear to represent the least risk, especially in northern climates, for becoming invasive plants. Further work is needed to assess the potential for seed ermination and competitiveness in nature. Nurseries and gardeners need to be aware of the potential invasiveness of this genus and be especially careful where field stock or mother plants are grown near open meadows and fields where seedlings could become established in native plant communities. For the full research report see: Meyer, M.H. and C. Tchida. 1999. Miscanthus Produces Viable Seed Across Four USDA Hardiness Zones. Journal of Environmental Horticulture Vol. 17(3): 137-140.

Soil Porosity and Time of Propagation Affect Growth of Five Ornamental Grasses

In the fall of 1997, five grasses were selected for this study based on popularity, desirable landscape characteristics, and availability. Two natives: prairie dropseed, Sporobolis heterolepsis, and little bluestem, Schizachyrium scoparium and three introductions: feather reedgrass, Calamagrostis xacutiflora Karl Foerster , and two cultivars of Miscanthus sinensis, Purpurescens and Variegatus were selected. The grasses were propagated by transplanting plugs or field divisions into either 4 inch round (480 ml), #1 (2.7L), or #2 (6.2L) nursery containers with composted rice hulls and Hubbard loamy sand media. Planting dates were between October 28 - November 10, 1997; April 30 - May 7, 1998; October 23 - 28, 1998; and May 1 - 10, 1999. Plants were covered with plastic and straw from the second week in November until the second week in April. Plants were evaluated for winter survival 6 weeks after uncovering and for finish dates every two weeks thereafter. Species and division time interacted to influence over-wintering survival. Spring divisions survived over-wintering 100% of the time regardless of species. Propagation time significantly affected the length of time it took some species to finish. Three fall handled species consistently finished within one year: S. scoparium plugs, C. xacutiflora 'Karl Foerster' divisions, and M. sinensis 'Purpurascens' divisions. Container size had a significant effect on finish date, but not on over-wintering survival.

Five grasses were propagated by transplanting plugs or field divisions into either 480 ml (4 inch round), 2.7L (#1), or 6.2L (#2) nursery containers containing media with ratios (v/v) of 0:1, 1:1, 2:1, 3:1, 1:0 rice hulls to sand, resulting in aeration porosities(%) in 2.7L containers of 5, 12, 22, 28, and 41, respectively. Planting dates were between October 28 - November 10, 1997, April 30 - May 7, 1998, October 23 - 28, 1998, and May 1 - 10, 1999. Plants were covered with plastic and straw from the second week in November until the second week in April. Winter survival was evaluated 6 weeks after uncovering and for finished dates every two weeks thereafter. Sporobolus heterolepis and Miscanthus sinensis . 'Variegatus' had significantly lower over-wintering survival. Schizachyrium scoparium , Calamagrostis xacutiflora 'Karl Foerster', and Miscanthus sinensis 'Purpurascens' performed almost equally well across media porosities. Overall, the sand medium resulted in lower root dry weights and crown diameters. Containers influenced growth as a function of volume with 6.2L containers having the greatest values for all growth parameters.

Objectives are to develop production guidelines for time of propagation and soil porosity recommendations. When final reports are published, the citations will be listed here.