2001 Annual Report Horticulture Section

Dickinson Research Extension Center 1089 State Avenue Dickinson, ND 58601

Xeriscape Ornamental Perennial Grass Trial for Low Water Use Landscaping

Llewellyn L. Manske and Jerry C. Larson
Range Scientist, NDSU, Dickinson Research Extension Center
Extension Agent, NDSU, Extension Service, Stark-Billings County

Western North America has increasing difficulty in providing adequate quantities of clean water for domestic use. A large portion of western municipalities' water supply is used for watering lawns, gardens, and landscape plants. Traditional landscaping frequently selects Kentucky bluegrass lawns and ornamental plants that require large amounts of water to remain beautiful. Several agencies and institutions joined Denver Water and the Associated Landscape Contractors of Colorado in 1981 to develop the concept of "Xeriscape" gardening. Alternatives to traditional techniques are being examined to develop landscapes that are harmonious with the local environmental conditions and use less water. Homeowners in western North Dakota have experienced the high costs of using domestic water for traditional landscape plants and have become aware of the need for alternative landscaping plants. Grass species in this trial are being tested and examined for use as plant material in low water use landscaping.

The purpose of Xeriscape gardening, or low water use landscaping, is to conserve expensive, precious domestic water by following seven simple commonsense principles.

*Use plants native to the region or plants adapted from areas with very similar environments and arrange the plants in zones with similar water, sun, and soil needs.

*Design the plants in arrangements that match family needs and lifestyle and select plants that provide color, texture, shade, and wind protection for all four seasons.

*Consider limitations of soil's water-holding characteristics and organic content and make improvements by amending the soil with composted plant material or aged manure.

*Limit turf grass lawns to areas actually used as "outdoor carpets" and select low water use grasses like blue grama, buffalo grass, crested wheatgrass, or tall fescue.

*Mulch with organic matter like wood or bark chips between plants to reduce evaporation and erosion; resist the use of plastic beneath decorator rock.

*Install water-wise irrigation systems and adjust them for maximum water savings with seasonal changes.

*Minimize maintenance to proper seasonal pruning and weed pulling and reduce fertilizer and pesticide applications.

Low water use landscaping achieves the desired goal of conserving water, money, leisure time, and precious resources while providing healthy, beautiful landscapes that add value to property. Xeriscape gardening combines landscaping with conservation.

Methods

This multi-year trial was designed to test and evaluate native grasses and adopted horticultural grasses as low water use ornamental landscape plants in western North Dakota. Thirteen native grasses and eleven horticultural domesticated grasses (Table 1) were included in this study. The research plots are located at the Dickinson Research Extension Center. These plots are managed with minimum maintenance, little supplemental irrigation water, no fertilizer, no herbicides after plot establishment, and hand roguing of weeds when necessary. The study consisted of three replications (Table 2). The grass plants were evaluated for vigor, ornamental value, seedhead aesthetics, color, and height. Vigor, ornamental value, and seedhead aesthetics were rated on a scale of 0-5 (Table 3). Color was recorded as one of twelve colors (Table 3). Total plant height was recorded as one of three height categories (Table 3). The twenty-four grass entries were randomly placed in plots in three replications (Table 4). Two evaluators rated each grass replication during initiation, early, mid-1, mid-2, late, and post growing-season periods.

Results

Mean evaluation ratings of grass entries are shown in Tables 5-10 for initiation, early, mid-1, mid-2, late, and post growing-season periods for 2000, respectively. Plants on replication plots of little bluestem, buffalo grass, Indiangrass, Canada wildrye, and sweetgrass died during the first year of the trial as a result of weakened condition caused by the plants' being covered by wood chips for several days and not receiving additional attention to assist the plants' recovery. These plants were replaced in the spring of 1999. Plants that expired from environmental conditions or natural causes were not replaced. The mean values of the evaluation ratings were determined for each growing-season period. Some ratings are reported with two mean values. The first value includes data from all three replications, and the second value includes data from only the active replications.

Most of the grass entries increased in vigor and ornamental value from initiation of growing-season, through mid-, and to late-season periods (Table 5-9). Several grass entries had medium to high vigor and ornamental value ratings during the initiation of growing-season period, and two entries had seedheads present in mid May, sweetgrass and blue fescue (Table 5). Vigor and ornamental value decreased for most grass entries from late to post growing-season periods (Tables 9-10). Several grass entries, blue grama, little bluestem, big bluestem, switchgrass, prairie cordgrass, feather reed grass, autumn red, altai wildrye, pampas grass, and blue fescue, had medium to high vigor and ornamental value ratings during the post growing-season period (Table 10). Most of the grass entries tended to have high seedhead aesthetics value ratings during the period from head-emergence to seed-development stages (Table 5-10). Several grass entries, little bluestem, big bluestem, sand bluestem, prairie sandreed, Indiangrass, switchgrass, prairie cordgrass, feather reed grass, red switchgrass, autumn red, altai wildrye, and pampas grass had medium or high attractiveness of seedheads after reaching full maturity and during the post growing-season period (Table 9-10).

Grass entries, sand love grass, giant silver banner grass, and zebra grass, had three or more sample periods with low vigor ratings and low ornamental values (Table 5-10). Several grass entries, blue grama, buffalo grass, big bluestem, sand bluestem, prairie sandreed, Indiangrass, switchgrass, prairie cordgrass, sweetgrass, feather reed grass, ribbon grass, blue lyme grass, autumn red, altai wildrye, pampas grass, and blue fescue, had three or more sample periods with high vigor ratings and high ornamental values (Table 5-10).

Most of the grass entries had distinctive attractive shades of green during the early, mid, and late growing-season periods (Tables 5-9). Many of the grass entries completed senescence during the late and post growing-season periods, displaying attractive shades of red, purple, or yellow before turning tan (Table 9-10).

The height categories for the grass entries (Table 11) were determined when the plants were mature and the seedheads had reached maximum height. Some of the grass entries grew relatively tall during the growing season of 2000. The grasses with seed heads taller than 6 feet were big bluestem, sand bluestem, prairie sandreed, prairie cordgrass, and pampas grass. Mature height of a plant is important in landscape design. The trial included three short-grass, thirteen mid-grass, and eight tall-grass entries.

Discussion

This is the third year of a multi-year trial designed to test and evaluate grass entries for use as ornamental plants for low water use landscaping. Most of the grass entries show positive potential for use as low water use landscaping plants. A few grass entries had one or more sample periods with low ratings, but these grasses should not be dismissed as landscape plants yet because the plants may improve. Some of the other grass entries may not maintain their moderate or high value ratings for the long run under these low maintenance and low supplemental water conditions.

Low water use landscaping, which uses native and/or adopted horticultural plants, is an important alternative to traditional landscaping, which uses plants that require large amounts of supplemental domestic water to remain beautiful. The results of this trial will assist homeowners in selecting ornamental perennial grass plants for use in their low water use landscaping.

Acknowledgment

The authors thank Ron Smith, NDSU Extension Horticulturist, Fargo, for providing plugs of horticultural adopted grass species plant material #13 to 20, for assisting with plot establishment, and for providing consultation during the development of this research project. We thank Craig Armstrong for providing plugs of horticultural adopted grass species plant material #22 and 23 and for providing advice on plot management. We thank USDA Plant Materials Center, Bismarck, for providing plugs of native species plant material #1 to 12. We thank Mike Knutson, USDA Plant Materials Center, Bismarck, for selection, collection, and delivery of native species plant material plugs and for assisting with plot establishment. We thank Jon Stika, NRCS, Area Agronomist, Dickinson, for making arrangements for native species plant material and for assisting with plot establishment. We thank James Nelson, DREC Animal Scientist, Dickinson, for preliminary preparation of plot area and for providing and spreading wood chips. We are grateful to Sheri Schneider for assistance in production of this manuscript. We are grateful to Amy M. Kraus and Naomi J. Thorson for assistance in preparation of this manuscript.

split values: includes 3 reps./only active reps.
Evaluation
vigor: Low 16, 17, 18, 19, 24
High 1, 3, 5, 7, 9, 10, 12, 13, 14, 15, 21, 23
Ornamental value: Low N/A
High 10, 13, 14, 21, 23

Split values: includes 3 reps./only active reps.
Evaluation
vigor: Low 2, 16, 17, 18, 19, 24
High 1, 3, 5, 6, 7, 9, 10, 12, 13, 14, 15, 20, 21, 22, 23
Ornamental value: Low 2, 16, 17, 18, 24
High 5, 6, 7, 9, 10, 12, 13, 14, 15, 21, 22, 23

Split values: includes 3 reps./only active reps.
Evaluation
vigor: Low 16, 17, 18, 24
High 1, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 20, 21, 22, 23
Ornamental value: Low 4, 16, 17, 18, 24
High 1, 3, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 20, 21, 22, 23

Split values: includes 3 reps./only active reps.
Evaluation
vigor: Low 16, 17, 18, 24
High 1, 3, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 20, 21, 22, 23
Ornamental value: Low 16, 17, 18, 24
High 1, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 19, 20, 21, 22, 23

Split values: includes 3 reps./only active reps.
Evaluation
vigor: Low 4, 16, 17, 18, 24
High 3, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 19, 20, 21, 22, 23
Ornamental value: Low 16, 17, 18, 24
High 1, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 19, 20, 21, 22, 23

(A)=senescent
(B)=covered by snow
Split values: Includes 3 reps./only active reps.
Evaluation
vigor: Low 16, 17, 18
High 21
Ornamental value: Low 16, 17, 18
High 5, 6, 13

Reference Literature

Barondeau, D., R. Smith, J. Larson, C. Miller, J. Dohrmann, T. Becker, R. Gaebe, B. Schmidt, J. Buckley, and L. Manske. 1997. Xeriscape plant selection. NDSU Extension Service. Fargo, ND. 22 min. Video tape.

Denver Botanic Gardens. No date. Water-smart gardening. Brochure. Denver Parks and Recreation Department. Denver, CO.

Denver Water. 1996. Xeriscape plant guide. American Water Works Association. Fulcrum Publishing. Denver, CO.

Denver Water. No date. Discover xeriscape. Pamphlet. Xeriscape Colorado Inc., Denver, CO.

Denver Water. No date. Efficient irrigation systems at work. Pamphlet. Office of Water Conservation, Denver, CO.

Hill, L. and N. Hill. 1995. Lawns, grasses and ground covers. Rodale Press, Emmaus, PA.

Plant Materials Center. 1997. Native grasses for prairie landscaping in the Northern Great Plains. Brochure. USDA Natural Resources Conservation Service. Bismarck, ND

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