Xeriscape Plant Selections and Ideas

H-957 (Revised), December 1994

Ronald C. Smith, Horticulturist
Rose Larson, Landscape Architect

"Xeriscaping" is a term North Dakotans should become more familiar with. A xeriscape is a landscape which uses plants that have low water requirements, making them able to withstand extended periods of drought. Xeric landscapes are a conscious attempt to develop plantings which are compatible with the environment.

Foundation plantings of shrubs and trees located randomly in the lawn and expanses of green, lush turf, all requiring vast amounts of water to be sustained, are not compatible with dry seasons in North Dakota. Plantings of this type originated in the eastern United States where rainfall averages 30 inches or more per year, with a fairly regular distribution pattern over the growing season. This usually allows plants to survive and, in most cases, thrive.

Xeric landscaping will require a change in styles as well as plant materials. Going "native" in plant selections is often thought to be synonymous with "drought resistant." Native plant establishment is often one of opportunity or timing; when the seeds make contact with the soil, whether adequate moisture is available, what the competition is, and whether there are herbivores. With these factors to consider, xeric landscaping should not be undertaken without proper planning, plant selection, and placement. For design ideas and principles, refer to NDSU Extension Circular Number H-958, "Landscape Ideas for North Dakota Homeowners."

The purpose of this publication is to provide a list of some plant materials which the North Dakota property owner may wish to consider to move toward more xeric, or less water demanding, landscape plants.

Grasses

Native

• Buffalograss (Buchloe dactyloides)
• Blue gramagrass (Bouteloua gracilis)
• Fairway crested wheatgrass (Agropyron cristatum `Ephraim')

Non-Native

• Hard Fescue (Festuca longifolia `Scaldis')
• Tall Fescue (Festuca arundinacea `Falcon')
• Red Fescue (Festuca rubra `Wintergreen')
• Kentucky Bluegrass (Poa pratensis -- the common types -- `South Dakota Certified', `Kenblue', `Park' and `Delta')
• Canada Bluegrass (Poa compressa `Cannon' or `Rubens'

Trees and Shrubs

Trees

• Acer negundo (boxelder maple)
• Pinus sylvestris (Scotch Pine) between P. ponderosa and Populous alba
• Celtis accidentalis (common hackberry)
• Fraxinus pennsylvanica (green ash)
• Juniperus species (juniper species)
• Juniperus scopulurumJ. virginiana
• Maackia amurensis (amur maackia)
• Picea glauca var. densata (Black Hill spruce)
• Picea pungens (Colorado spruce)
• Pinus flexilis (limber pine)
• Pinus ponderosa (ponderosa pine)
• Populus tremuloides (quaking aspen)
• Quercus macrocarpa (bur oak)

Medium Trees

• Aesculus glabra (Ohio Buckeye)
• Crataegus spp. (Hawthorn)

Small Trees

• Acer ginnala (Amur mpale)
• Elaeagnus angustifolia (Russian olive)
• Elaeagnus commutata (Silverberry)
• Prunus americana (American plum)
• Prunus virginiana (Chokecherry)

Shrubs

• Acer ginnala (Amur maple)
• Artemisia species (artemisia)
• Caragana species (Siberian pea-shrub)
• Eleagnus angustifolia (Russian olive)
• Eleagnus commutata (Silverberry), J. communis, J. horizontalis, J. sabina
• Juniperus species (junipers)
• Lonicera x xylosteoides `Clavey's Dwarf' (Clavey's Dwaft honeysuckle)
• Lonceria tatarica `Arnold Red'
• Potentialla species (potentillas)
• Prinsepia sinensis (cherry prinsepia)
• Prunus americana (American plum)
• Prunus virginiana (chokecherry)
• Rhus glabra (smooth sumac)
• Rhus trilobata (skunkbush)
• Ribes alpinum (alpine currant)
• Shepherdia argentea (buffalo berry)
• Spirea trilobata (threelobe spirea)
• Spirea vanhoutii
• Syringa species (lilac)
• Viburnum lentago (nannyberry viburnum)
• Yucca glauca (soapwood)

Flowers and Ground Covers

• Achillea tomentosa -- Wolly Yarrow
• Asclepias tuberosa -- Butterfly Weed
• Anthemis tinctoria -- Golden Marguerite
• Centaurea montana -- Mountain Bluet (perennial bachelor's button)
• Cerastium tomentosum -- Snow in Summer
• Coreopsis spp. -- many good cultivars to select from
• Dianthus plumarius -- Border Pink, Scotch Pink, Grass Pink
• Echinacea purpurea -- Purple Coneflower
• Gypsophila paniculata -- Baby's Breath
• Hemerocallis spp. -- Daylily
• Linum perenne -- Blue Flax
• Oenothera spp. -- Sundrops
• Perovskia atriplicifolia -- Russian Sage
• Stachys spp. -- Lamb's Ears(many cultivars to select from)

Drought tolerance is not simply a function of genetic capability. Many of these species, if watered frequently, will not prove to be drought tolerant if water is suddenly withheld. Plants previously subjected to water stress suffer less from drought than plants not previously stressed. Nurserymen realize this and "harden" their transplants to the field or landscape for better survival by decreasing the frequency of watering and exposing the plants to full sun.

If the homeowner cannot make a commitment to keep water supplied to the plants throughout the growing season, then early season water reductions should be practiced.

It should be noted that some of the plants are considered borderline tolerant. That is, some have successfully been established in certain regions of the state without showing environmental injury. Two examples would be the honeylocust and catalpa. Check to see if a species you are considering has been successfully grown in your area before making a large investment.

The Importance of Mulching to Conserve Water

There is a wide variety of products to use for mulching purposes. The organic mulches include peat moss, manure, compost, leaf mold, and sawdust. They all have the advantages of saving or conserving moisture, slowly providing nutrients, changing the chemistry of the soil, changing the physical structure, and fairly low cost. They need to be added on a regular (annual at least) basis because of microbial breakdown.

Some inorganic mulches such as plastic sheeting, sand, vermiculite and perlite add no nutrients, are subject to movement by the wind and moving water, and are generally unaffected by microbial action.

Generally, the mulches work best on vegetable and flower plantings, shrub beds and some trees, but could actually be detrimental to native plantings. Mulches should not be placed against the trunks of trees, but set back a few inches to keep rodents from feeding on the bark during the winter.

Remember that material that is too "fresh" -- that is, not weathered, will tie up nitrifying microorganisms during the initial process and may cause nitrogen deficiency to the plants they are placed around. If a nitrogen deficiency occurs, the addition of some water soluble nitrogen fertilizer to the mulch will correct the problem.

Zonal Planting Concepts

In the truly arid parts of the country, such as Arizona, eastern Colorado and west Texas, the Xeriscape concepts are practiced via zoning around the house. With this concept, the high water requiring plants are planted close to the house, often given the term "oasis zone" (zone #1). The moderate, or regular watering zone (zone #2), would contain plant materials that, after establishment, would require only occasional watering during extended droughty periods.

The "no water zone" (zone #3) could have some native plant species that have adapted to the usual precipitation patterns of the particular region. Here, plants would need water for the first year (usually through a drip irrigation system) to become established, then allowed to go it entirely on their own.

With the three zones clearly defined, it is obvious that three entirely different classes of plant materials will be needed. This takes careful thought in planning and planting to avoid a hodgepodge design.

H-957, December 1994