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University of Rhode Island GreenShare Factsheets

Drought-Tolerant Plants

There are plants in most landscapes that survive periods of drought. Placing these plants in the garden reduces the need to supply extra water during periods of inadequate rainfall. While cacti and succulents may have a place in some drought-tolerant gardens, they are not the only alternatives. There are other choices available which are appropriate for dry areas. With careful selection, planning and execution, drought-tolerant landscapes can be as pleasing as those needing heavy irrigation.

Select Plants for the Growing Conditions:

Select plants for the growing conditions in a given area when planning and designing the landscape. These growing conditions create microclimates. Define the microclimates. Create a site plan that groups plants according to similar water needs. Strive for three basic divisions: very low water zone, low water zone and moderate water zone. Each area should be irrigated separately, according to specific water needs. Incorporate leaf size and color, bloom period and size and shape of plant to create visual interest.

Soil type, wind and exposure to sun can create a dry microclimate in an area that receives heavy rainfall. Sandy, well-drained soil will dry out more quickly, while heavy clay soils (rare in Rhode Island) are likely to remain moist much longer. Mixing humus into the soil will improve water-holding capacity of sandy soils and water penetration in clay soils. Sandy soils with humus will hold larger amounts of water. Clay soils amended with humus will absorb more water, reducing runoff. In locations with poor drainage and heavy soils, many drought-tolerant species may suffer during years with average or abundant rainfall. Wet winters and spring rains may also cause problems for some drought-tolerant plants growing in heavy soils.

Limit Turfgrass:

Turfgrass requires more water than other plants in the landscape. By isolating turf from gardens, trees and shrubs, a gardener can separate irrigation zones and waste less water. Limit turf to areas that are regular in shape and easily irrigated. Cultivar selection should be appropriate to the climate, site, level of maintenance, intended use and reduced water consumption. Although coarse in texture and appearance, tall fescue mixes offer good heat and drought tolerance. Cut the grass at a height of 2 1/2 to 3 inches. Longer leaf blades help to shade and cool the ground, reducing evaporation from the soil and lessening the need to irrigate.

Irrigate Efficiently:

Efficient irrigation may mean including an irrigation system. The least efficient system is the sprinkler, which delivers a large amount of water in a short period, but loses excessive amounts of moisture to evaporation. Sprinklers are the only choice for turf areas, however. Low-volume trickle or drip irrigators and soaker hoses deliver moisture over a long period, losing little water to evaporation or runoff. Check all systems regularly. An improperly calibrated, clogged or leaking system can waste a great deal of water. Carefully probe the root zone to help determine the moisture content in the soil. With some low-volume systems, the surface of the soil will not appear to be saturated, while the root zone will receive the proper amount of moisture.

In times of drought, utilizing recycled household or graywater helps ease water usage. Graywater should be free from oils, food scraps and bleach. Mixing graywater and fresh water (half and half) is ideal. Graywater should not be used on root crops or potted plants or be a plant's sole source of water. In addition to graywater, saving rainwater from roofs in cisterns and rain barrels will lessen the need to use community or well water. The need for irrigating an area will depend on all the factors of culture and microclimate. Well-established gardens will require less supplemental irrigation during drought than newly planted areas.

Use Mulch Properly:

Properly mulching an area lowers the soil temperature and decreases the loss of moisture due to evaporation. In addition to creating texture in the landscape, organic mulches decay and add nutrients to the soil. Appropriate depth of the mulch is important: 2 to 3 inches for trees and shrubs and 1 to 2 inches for vegetables, annuals and perennials.

Carefully planned landscapes and sound cultural practices reduce water needs. Controlling weeds will lower moisture competition with other plants. Lessening competition will strengthen existing plants and make them less susceptible to disease, insects and drought. By carefully preparing and meeting plant requirements, a gardener can develop a landscape full of color and texture while concurrently reducing water requirements.

Irrigation Zones:

Very Low Water Zone:
This area is typically farthest from a source of water. Plants in this area must be chosen carefully, requiring little or no supplemental irrigation. Some of these plants may show problems in years of abundant rainfall.

Low Water Zone:
Plants chosen for this area will require more water than that which is available naturally. During severe drought, supplementing the water supply will become necessary.

Moderate Water Zone:
This zone will use the greatest ratio of water in the landscape. Keeping this area small will help limit water needs. It is possible to grow drought-intolerant plants in this area.

Plants Selected For Low And Very Low Water Zones:

Hardiness may be microclimate dependent. This is not a complete list, but rather a sample of drought-tolerant trees and shrubs.

Some species (1) require well-drained soils and will not grow well in poorly drained, clay soils. Some species resistant to drought may perform more vigorously when grown in ideal conditions.

Abies concolor -- White or Concolor Fir
Acer campestre -- Hedge Maple
Acer ginnala -- Amur Maple
Acer tataricum -- Tatarian Maple
Acer truncatum -- Painted Maple
Aesculus pavia -- Red Buckeye
Amorpha fruticosa -- Indigobush
Aralia spinosa -- Devil's Walkingstick
Arctostaphylos uva-ursi (1) -- Bearberry
Aronia arbutifolia -- Red Chokeberry
Aronia melanocarpa -- Black Chokeberry
Berberis x mentorensis -- Mentor Barberry
Caragana arborescens -- Siberian Peashrub
Carpinus betulus -- Common or European Hornbeam
Ceonothus americanus -- American Ceonothus
Ceonothus ovatus -- Inland Ceonothus
Cephalotaxus harringtonia -- Japanese Plum Yew
Chaenomeles speciosa -- Flowering Quince
Cladrastus kentukea -- American Yellowwood
Comptonia peregrina -- Sweetfern
Cornus racemosa -- Gray Dogwood
Corylus americana -- American Filbert
Corylus colurna -- Turkish Filbert
Cotinus coggygria -- Purple Smokebush (Smoketree)
Cotinus obovatus -- American Smoketree
Cotoneaster adpressus -- Creeping Cotoneaster
Cotoneaster divaricatus -- Spreading Cotoneaster
Cotoneaster salicifolius -- Willowleaf Cotoneaster
Cratageus viridis 'Winter King' -- Winter King Green Hawthorn
Diervilla sessilifolia -- Southern Bush Honeysuckle
Eleutherococcus sieboldianus
Eucommia ulmoides -- Hardy Rubber Tree
Exochorda racemosa -- Common Pearlbush
Fagus sylvatica -- Common or European Beech
Fraxinus pennsylvanica -- Green Ash
Ginkgo biloba -- Gingko or Maidenhair Tree
Gymnocladus dioicus -- Kentucky Coffee Tree
Hammamelis mollis -- Chinese Witchhazel
Hammamelis vernalis -- Vernal Witchhazel
Hammamelis virginiana -- Common Witchhazel
Hammamelis x intermedia 'Arnold Promise' -- Arnold Promise Witchhazel
Hydrangea arborescens -- Smooth Hydrangea
Hypericum species -- St. John's Wort
Juniperus chinensis -- Chinese Juniper
Juniperus conferta -- Shore Juniper
Juniperus virginiana -- Eastern Red Cedar
Koelreuteria paniculata -- Golden Raintree
Kolkwitzia amabilis -- Beautybush
Maackia amurensis -- Amur Maackia
Malus species -- Apple
Myrica pensylvanica -- Bayberry (Northern)
Ostrya virginiana -- American Hop Hornbeam or Ironwood
Oxydendrum arboreum -- Sourwood or Lily of the Valley Tree
Parrotia persica -- Persian Parrotia
Parthenocissus quinquifolia -- Virginia Creeper
Parthenocissus tricuspidata -- Japanese Creeper
Phellodendron amurense -- Amur Corktree
Physocarpus opulifolius -- Common or Eastern Ninebark
Picea omorika -- Serbian Spruce
Picea orientalis -- Oriental Spruce
Pinus banksiana -- Jack Pine
Pinus bungeana -- Lacebark Pine
Pinus cembra -- Swiss Stone Pine
Pinus koraiensis -- Korean Pine
Pinus parviflora -- Japanese White Pine
Pinus strobus -- Eastern White Pine
Potentilla fruticosa -- Bush Cinquefoil
Prunus maritima -- Beach Plum
Prunus sargentii -- Sargent's Cherry
Pyrus calleryana cultivars -- Callery Pear
Quercus acutissima -- Sawtooth Oak
Quercus alba -- White Oak
Quercus bicolor -- Swamp White Oak
Quercus imbricaria -- Laurel or Shingle Oak
Quercus phellos -- Willow Oak
Quercus rubra -- Red or Northern Red Oak
Quercus shumardii -- Shumard Oak
Rhus aromatica 'Gro-Low' -- Gro-Low Fragrant Sumac
Rhus chinensis -- Chinese Sumac
Rhus copallina -- Shining Sumac
Sarcococca hookeriana -- Himalayan Sarcococca
Sciadopitys verticillata -- Japanese Umbrella Pine
Sophora japonica -- Scholar Tree or Japanese Pagoda Tree
Spiraea x bumalda 'Anthony Waterer' -- Anthony Waterer Bumald Spirea
Spiraea x vanhouttei -- Vanhoutte Spirea
Symphoricarpos x chenaulti -- Chenault Coralberry
Syringa reticulata -- Japanese Tree Lilac
Taxodium ascendens -- Pond Bald Cypress
Taxodium distichum -- Common Bald Cypress
Tetradium daniellii
Thuja plicata -- Giant Arborvitae
Tilia tomentosa -- Silver Linden
Ulmus parvifolia -- Chinese or Lacebark Elm
Vaccinium angustifolium -- Lowbush Blueberry
Vaccinium corymbosum -- Highbush Blueberry
Viburnum acerifolium -- Mapleleaf Viburnum
Viburnum dentatum -- Arrowwood Viburnum
Viburnum prunifolium -- Blackhaw Viburnum
Viburnum rhytidophyllum -- Leatherleaf Viburnum
Viburnum sieboldii -- Siebold Viburnum
Viburnum x rhytidophylloides -- Lantanaphyllum Viburnum
Weigela florida -- Old fashion Weigela
Xanthorhiza simplicissima -- Yellowroot

 

Adapted from Michael T. Loos, Ohio State University Extension, 2000

Pesticides are poisonous! Read and follow all safety precautions on labels. Handle carefully and store in original containers out of reach of children, pets or livestock. Dispose of empty containers immediately, in a safe manner and place. Pesticides should never be stored with foods or in areas where people eat.

When trade names are used for identification, no product endorsement is implied, nor is discrimination intended against similar materials. Be sure that the pesticide you intend to use is registered for the state of use.

The user of this information assumes all risk for personal injury or property damage.

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For more information, call the URI CE Gardening and Food Safety Hotline at 1-800-448-1011 or (401)874-2929 from outside Rhode Island; Monday-Thursday between 9 am and 2 pm.

 

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