G1214

Perennials In Water-Wise Landscapes

This NebGuide discusses choosing, establishing, and maintaining perennial flowers in water-wise landscapes.


Kim W. Todd, Extension Horticulture Specialist
Dale T. Lindgren, Extension Horticulture Specialist
Elizabeth M. Killinger, Extension Educator — Horticulture


Drought-tolerant perennials are plants that persist for three or more years with little or no supplemental watering. There are both native and introduced herbaceous plants that are drought-tolerant. Using these plants in Nebraska landscapes will help conserve water, reduce the maintenance associated with watering, and still provide multi-season color and interest. Many drought-tolerant plants perform poorly in areas and seasons of high humidity and rainfall, or with excessive irrigation. For example, some drought-tolerant perennials may perform well in western Nebraska but prove to be less than satisfactory in eastern Nebraska.

Site Selection and Design

Many drought-tolerant perennials do best in full sun and well-drained soil, although a few thrive in dry shade. Areas of the landscape that are difficult to water, or are subject to reflected heat and light, are often good locations for drought-tolerant perennials. A primary principle of landscape design to manage water is to group plants that have similar water requirements. Good design also takes into consideration the cultural requirements of each plant, microclimate, the background or setting for the landscape, and the scale or size of the space. Those major factors influence the choice and spacing of individual plants, and how they can best be combined for a beautiful landscape.

Size, Spacing, and Form — The size of your planting space will influence the choice of plants. Make sure perennials are spaced for their mature size — it is easy to put them too close together when you purchase them as small plants. Some perennials grow larger than the size listed on the label, especially when grown in ideal conditions. Good spacing allows air circulation, which is essential to allow the foliage of drought-tolerant plants to dry adequately and reduce the possibility of disease.

The form of many perennials changes as the season progresses. Plants with bold, contrasting forms can be used as individual focal points, while others are best planted in groupings or drifts of three or more. This deliberate use of contrast and similarity will create both variety and continuity in your landscape.

Texture and Color — The color, timing, and duration of the flowers is an important consideration, but foliage color also contributes to the overall design. Many drought-tolerant perennials have silver or gray foliage, which shines in low light and acts as a foil for brighter colors. Warm colors attract attention, and make spaces seem smaller and hotter. Cool colors and pastels are tranquil.

Unique leaf structure helps many drought-tolerant perennials reduce water loss through transpiration and adds textural interest. Fine, lacy foliage with reduced leaf surface; thick, waxy succulent foliage; or broad, fuzzy leaf blades can reduce water loss from plants and provide many options for using the texture of perennials to extend the visual interest of the landscape well beyond the bloom period.

Foliage and seed heads of many drought-tolerant perennials can be left in place well into the winter with a backdrop of ornamental grasses or evergreens, providing an extended season of interest. Leaving the foliage in place until spring holds leaves and snow as insulation, protecting the roots of plants from winter injury. However, care should be taken to keep this material from sitting on the crowns of plants, because good air circulation and drainage are essential to survive through winter.

Site Preparation for Establishment

A well-drained, friable (loose) soil is essential for the survival of drought-tolerant plants. This soil structure will allow the roots of water-conserving plants to extend deeply into the soil. Most drought-tolerant plants in the home landscape benefit from the addition of organic matter to the soil. Organic matter loosens the soil and adds nutrients. Sandy soils, which drain very quickly, benefit from the addition of organic matter by improved nutrient- and water-holding capacity, and reduced runoff of nitrogen and pollutants. If the soil is very poorly drained, small rocks, pebbles, or coarse sand may be added to improve conditions for the most drought-tolerant plants.

Loosen existing soil to a depth of at least 12 inches to break up any sites severely compacted by construction or traffic. Thoroughly mix organic matter such as coarse compost, shredded leaves, or a combination of these materials, into the loosened soil at a ratio of approximately one part organic matter to four parts soil. For example, use 3 inches of organic matter on a soil loosened to a depth of 12 inches.

Maintenance

Even the most drought-tolerant perennials require supplemental water until they are established, as well as during periods of extended drought. The smaller the root system, the more frequently you will need to water newly installed perennials. Check the soil beyond the root zone as well, and apply one-half inch to 1 inch of water weekly inclusive of rainfall. Gradually reduce the amount of supplemental water, but continue to monitor the condition of the plants.

Mulch new and established perennials with a layer of material 1 to 2 inches deep to retain soil moisture, suppress weed growth, and reduce erosion. Organic mulches are recommended for all but the most drought-tolerant plants. Medium-textured wood chips, shredded bark, chopped leaves, or a combination of these materials look natural and improve the soil composition as they decompose. Inorganic mulches like rock or gravel hold heat and reflect light, and may damage the plants they are intended to protect.

Fertilize drought-tolerant perennials only when the plants show signs of diminished vigor or chlorosis. The breakdown of organic mulches adds nutrients to the soil, but fertilizer may eventually be needed if mulches or compost are not regularly replenished.

Most drought-tolerant plants will perform well for years without division and may actually be destroyed if they are disturbed. Others will respond to overcrowding by dying out in the center, becoming spindly, or failing to produce vigorous blooms. Drought-tolerant perennials may be divided and replanted as soon as the soil is workable in the spring or in late August to early September. Gently lift the old clump, and remove dead pieces with a sharp knife or spade. Split the plant into two or more sections, and place each section in a new planting hole at the same depth or slightly higher than the original plant. Backfill with soil that is consistent with the surrounding area, and water until the soil is saturated. Do not tamp the soil or otherwise compact it.

Following is a list of perennials that have demonstrated a tolerance of Nebraska moisture conditions, including soil moisture stress, when planted in well-drained soils.

The list includes native and non-native or adapted plants that are not invasive. The most drought-tolerant plants are indicated with an asterisk. Bloom times are approximate, since they are influenced by climate factors and microclimate. Exposure refers to the amount of sun that each plant prefers; many plants will tolerate more or less than an ideal exposure, but habit and bloom may be affected. Only a few of the many cultivars that may be available are listed.

Common Name Scientific Name Select Varieties Bloom Color Ht/Spr. Bloom Sun Remarks
Allium, Ornamental Allium senescens ‘Glaucum’ Lavendar 12”-12” July-Sept S Long bloom season
Apple-blossom Grass, Gaura Gaura lindheimeri ‘Siskiyou Pink’ Pink 36”-36” June-Sept S Short-lived
Artemisia, Fringed * Artemisia frigida   Silver foliage 30”-30” No bloom S Native
Artemisia, Southernwood Artemisia abrotanum   Gray-green foliage 36”-36” No bloom S/Psh Semi-woody
Artemisia, White Sage Artemisia ludoviciana ‘Silver King,’
‘Valerie Finnis’
Silver foliage 36”-48” No bloom S/Psh Aggressive
Arum, Painted Arum italicum ‘Pictum’ Green 12”-12” May Psh/Sh Summer dormancy, semi-evergreen
Aster, Dwarf Aster x dumosus ‘Prof. Kippenburg,’
‘Woods’
Pink, purple, white 12”-18” Sept-Oct S/Psh Dwarf, attract butterflies
Aster, Fendler’s Aster fendleri ‘My Antonia’ Purple, white 6”-12” July-Sept S Native, good drainage
Aster, New England Aster novae-angliae ‘Alma Potschke,’
‘Purple Dome’
Pink, purple, white 48”-36” Sept-Oct S/Psh Taller, attract butterflies
Baby’s Breath Gypsophila paniculata ‘Fairy Perfect,’
‘Bristol Fairy’
White 24”-24” June S Best on higher pH soils
Barrenwort, Red Epimedium x rubrum   Red 9”-18” Apr-May Psh/Sh Semi-evergreen
Bergamot, Wild Mondarda fistulosa   Pink-lavendar 18”-18” June-Aug S/Psh Colonizes
Blackberry Lily Belamcanda chinensis ‘Hello Yellow’ Orange, yellow 18”-36” July S/Psh Can be weedy/seeds itself
Black-eyed Susan Rudbeckia hirta   Yellow-orange 24”-24” July S  
Black-eyed Susan, Goldsturm Rudbeckia fulgida ‘Goldsturm’ Yellow-orange 24”-24” July-Sept S/Psh Seeds itself
Blanket Flower * Gaillardia aristata ‘Baby Cole,’
‘Goblin,’
‘Burgunder’
Yellow-red, red 18”-24” June-Sept S Seeds itself, can be short-lived
Blue Flax Linum perenne ‘Saphir,’
‘Album’
Blue, white 24”-18” May-June S Flowers close in heat
Bluet, Mountain Centaurea montana   Blue 24”-18” May-July S Best central/west
Boltonia Boltonia asteroides ‘Snowbank’ White 60”-48” Aug-Sept S Self-supporting
Butterfly Milkweed Asclepias tuberosa   Orange 24”-24” June-July S Native, attracts butterflies
Calamint, White Cloud Calamintha nepetoides ‘White Cloud’ White 12”-18” June-July S Fragrant foliage
Candy Lily Pardancanda norrisii ‘Dazzler’ Mixed 18”-18” July-Sept S Unusual flowers
Catmint Nepeta x faassenii ‘Walkers Low,’
‘Six Hills Giant’
Blue 18”-24” May-Sept S Shear for repeat bloom
Comfrey Symphytum grandiflorum ‘Hidcote Blue’ Blue 12”-12” May Psh/Sh Coarse texture in shade
Coneflower, Grayhead Prairie * Ratibida pinnata   Yellow 48”-24” July-Sept S Native, attracts butterflies
Coneflower, Narrow-leaf Purple Echinacea angustifolia   Purple, white 36”-24” June-July S Native, attracts butterflies
Coneflower, Pale * Echinacea pallida   Purple-pink 30”-24” June-July S Native, most drought-tolerant species
Coneflower, Purple Echinacea purpurea ‘Magnus,’
‘Cygnet White’
Purple, pink, white 36”-24” June-Aug S/Psh Seeds itself, attracts butterflies
Coreopsis, Threadleaf Coreopsis verticillata ‘Moonbeam,’
‘Zagreb’
Yellow 18”-36” June-Sept S/Psh Long bloom season
Cranesbill, Bigroot Geranium macrorrhizum ‘Bevan’s Variety’ Pink 18”-24” May Psh/Sh Semi-evergreen
Daylily * Hemerocallis spp. Many Mixed Varies June-Oct S/Psh Many rebloomers
Dwarf False Indigo Baptisia australis var. minor   Blue 30”-30” May S/Psh Interesting seed pods
False Indigo Baptisia australis   Blue 48”-24” May S/Psh Shrub-like proportions
Gayfeather, Dotted * Liatris punctata   Rose-purple 24”-24” July-Aug S Native, attracts butterflies
Gayfeather, Rough Liatris aspera   Rose-purple 30”-24” Aug-Oct S Native, best east/northeast
Gayfeather, Spike Liatris spicata ‘Kobold,’
‘Floristan White’
Rose-purple, white 30”-24” June-July S Native, good cut flower
Globe Thistle Echinops ritro ‘Taplow Blue’ Blue 24”-24” June-Sept S Steel blue flowers
Goldenrod, Canada Solidago canadensis ‘Crown of Rays,’
‘Golden Baby’
Yellow 18”-15” July-Sept S/Psh Rebloom if cut back
Goldenrod, Stiff * Solidago rigida   Yellow 36”-24” July-Sept S/Psh Native, good cut flower
Hens and Chicks * Sempervivum spp. Many Mixed 6”-12” July S Rock garden plants
Hollyhock Alcea rosea ‘Chater’s Double,’
‘Nigra’
Mixed 36”-72” June-Aug S Can be short-lived; reseeds
Horehound, Roundleaf * Marrubium rotundifolium   Green-silver foliage 6”-18” No bloom S Unusual foliage; rock wall plant
Hosta Hosta spp. Many White, lavendar Varies Aug-Sept Psh/Sh Compete well with tree roots
Hummingbird Mint, Sunset Hyssop * Agastache rupestris   Orange-purple 18”-18” Aug-Sept S Short-lived, best in central/west
Iris, Bearded * Iris spp. Many Mixed Varies May-June S Protect tall varieties from strong wind
Knautia Knautia macedonica ‘Mars Midget’ Red 24”-24” June-Oct S Long bloom season, unusual color
Lambsear, Helene von Stein * Stachys lanata ‘Helene von Stein’ Gray-green foliage 18”-24” No bloom S/Psh Avoid standing water or snow on crown
Lavendar * Lavandula angustifolia ‘Provence,’
‘Hidcote,’
‘Munstead’
Lavendar blue 18”-18” June-July S Semi-woody, shear for best form
Leadplant * Amorpha canescens   Lavendar-blue 36”-36” June-July S Native shrub useful in perennial beds
Lily-of-the-Valley Convallaria majalis   White 6”-36” May Psh/Sh Aggressive
Mother-of-Thyme Thymus serpyllum   Pink 6”-18” July S Can be stepped on, will recover
New Jersey Tea Ceanothus americanus   White 30”-36” June-Aug S Native
Oregano, Ornamental Origanum laevigatum ‘Herrenhausen,’
‘Rosenkuppel’
Rose-purple 18”-18” Aug-Sept S/Psh Stems turn purple during season
Pasqueflower * Pulsatilla patens   Purple 12”-12” Apr-May S Native, attracts butterflies
Penstemon Penstemon digitalis ‘Husker Red’ Pink-white 24”-18” May-June S Purple foliage; good seed heads
Penstemon, Rocky Mountain * Penstemon strictus ‘Bandera’ Purple, salmon 24”-36” June-July S Good drainage required
Penstemon Penstemon ‘Sweet Joanne’ Dark pink-purple 30”-18” June-frost S Disease-resistant, extremely hardy
Penstemon, Shell-leaf * Penstemon grandiflorus ‘Prairie Snow,’
‘War Axe’
Pink, white, purple 30”-18” May-June S Good drainage required
Peony Paeonia lactiflora Many Pink, white 36”-36” May-June S Cage to hold flowers upright
Periwinkle, LaGrave Vinca minor ‘LaGrave’ Lavendar-blue 6”-18” Apr-May Psh/Sh Competes well with tree roots
Phlox, Prairie Phlox pilosa ‘Eco Happy Traveler’ Pink 12”-12” May-June S/Psh Native, strong bloomer
Pinks, Cheddar Dianthus gratianopolitanus   Pink 6”-18” May-June S Silver foliage, clove-scented flowers
Pitcher Sage * Salvia azurea ‘Nekan’ Blue 48”-24” July-Sept S Native, unusual fall color
Poppy Mallow, Logan Calhoun * Callirhoe alcaeoides ‘Logan Calhoun’ White 12”-48” June-Aug S Groundcover
Poppy Mallow, Purple * Callirhoe involucrata   Maroon 12”-48” June-Aug S Native, long bloom season
Prairie Baptisia Baptisia leucantha   White 48”-24” June S/Psh Native, interesting form
Prairie Clover, Purple * Dalea purpurea ‘Stephanie’ Pink 18”-24” June-July S Native, good drainage best
Prairie Clover, Silky Dalea villosa   Pink 18”-24” July-Aug S Native, best in central/west, sandy soils
Prairie Petunia * Ruellia humilis   Lavendar-purple 12”-12” June-Aug S Native, aggressive seeder
Prairie Smoke Geum triflorum   Pink 12”-12” Apr-May S/Psh Native, interesting seedheads
Primrose, Missouri Oenothera macrocarpa ‘Comanche Campfire’ Yellow 6”-24” June-Aug S Native, stems and pods interesting
Puccoon * Lithospermum incisum   Yellow 6”-12” Apr-June S Best in central/west or well-drained soils
Pussytoes * Antennaria neglecta   White, pink 2”-12” May-June S Tiny groundcover for driest sites
Rabbit-brush * Chrysothamnus nauseosus   Yellow 24”-24” July-Sept S Best in central/west or well-drained soils
Rattlesnake Master * Eryngium yuccifolium   Green-white 48”-24” July-Sept S Unusual form, seeds itself
Rock-Cress, Wall Arabis caucasica   Pink, white 4”-12” Apr-May S Rock garden plant
Russian Sage Perovskia atriplicifolia ‘Filigran,’
‘Longin’
Blue 48”-36” July-Aug S Semi-woody, can seed
Saltbrush, Four-winged * Atriplex canescens   Silver foliage 24”-24” NA S Best in central/west or well-drained soils
Sea Holly Eryngium amethystinum   Blue 24”-18” July-Aug S Interesting foliage and flowers
Sedum, Low Varieties * Many Many Mixed Varies June-Oct S/Psh Versatile
Sedum, Tall Varieties * Many Many Pink, red, white Varies June-Oct S/Psh Versatile
Shasta Daisy Leucanthemum x superbum ‘Becky,’
‘Crazy Daisy’
White 24”-24” June-Oct S Good cut flowers
Skull Cap, Helmet Flower Scutellaria scoridifolia ‘Mongolian Skies’ Blue-purple 6”-12” May-June S Edger; good drainage required
Snakeroot, White Eupatorium rugosum   White 30”-36” Aug-Sept Psh/Sh Aggressive reseeder
Snow-in-Summer * Cerastium tomentosum   White 4”-24” Apr-May S Mat-former
Solomonseal, Variegated Polygonatum multiflorum ‘Variegatum’ Green-white 24”-36” May Psh/Sh Colonizes
Spiderwort, Narrow-leaved Tradescantia tharpii   Blue, pink, white 12”-12” May S/Psh Best in central/west or well-drained soils
Spirea, Blue Mist Caryopteris x clandonensis ‘Dark Knight,’
‘Arthur Simmonds’
Blue 36”-36” Aug-Sept S Semi-woody, may winter kill
Statice, German Goniolimon tataricum ‘Woodcreek’ White 18”-18” June-July S Tough, good cut flower
Sundrops, Yellow Calylophus serrulatus ‘Prairie Lode’ Yellow 6”-18” May-July S Good edger
Sun-Rose * Helianthemum nummularium ‘Wisley Pink’ Pink, white, orange 6”-12” May-June S Wall plant
Thrift Armeria maritima ‘Rubra’ Pink 6”-12” May S Wall plant
Valerian, Red Centranthus ruber ‘Pretty Betsy,’
‘Albus’
Red-pink, white 30”-30” May-June S/Psh Good drainage, good wall plant
Veronica, Silver * Veronica incana   Blue 12”-18” June S Silver foliage
Virginia Mountainmint Pycnanthemum virginianum   Green-white 24”-24” July-Sept S/Psh Attracts butterflies, doesn’t spread
Yarrow, Common * Achillea millefolium ‘Terracotta,’
‘Paprika,’
‘Snowsport’
White, red, orange 30”-24” June-Aug S Versatile, like low fertility
Yarrow, Hybrids * Achillea ‘Moonshine,’
‘Schwellenburg’
Yellow 24”-24” June-July S Versatile, like low fertility
Yarrow, Serbian * Achillea serbica   White 4”-12” May S Tiny groundcover for driest sites
Yucca, Soapweed * Yucca glauca,
Yucca filamentosa
  White 36”-36” June S Native, semi-evergreen
S=Sun; Psh=Part Shade; Sh=Shade
Bloom times are approximate
*Most drought tolerant

This publication has been peer reviewed.


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