Drought-Tolerant Landscapes for Alabama - Alabama A&M University


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Drought-Tolerant Landscapes for Alabama - Alabama A&M University

  1. 1. A la b ama A & M a n d A u b u r n U n i v e r s itie s Drought-Tolerant Landscapes for Alabama ANR-1336IntroductionA well-designed and managed landscape can reduce theamount of water needed for homelandscape irrigation. This conserva-tion of water becomes increasinglyimportant as municipal governmentsimpose broad watering bans inresponse to drought situations thatcreate water shortages and strainedwater supplies. Overhead landscapeirrigation is usually the target of thesewater conservation policies because itis viewed as noncritical consumption. Some plants perform well with only Thoughtfully planned, attractive occasional irrigation.landscapes are important becausethey provide environmental benefitsand add value and beauty to homes.The environmental benefits include Planning for Efficient areas, or hydrozones. Walk around thereducing soil erosion and storm water Use of Water landscape and identify places whererunoff, providing wildlife habitats, the soil stays moist longer and sepa- It is important to plan a designremoving carbon dioxide and pollut- rate them from the areas fully exposed for the landscape. The types of plantsants from the atmosphere while to the sun where the soil tends to used and their location, the conditionadding oxygen, and keeping homes dry quickly. of the soil, and other factors all affectcooler in the summer and protecting Low-water-use hydrozones how much water must be used tothem from cold winds in the winter. should comprise as much of the maintain the landscape. Homeowners can ensure a landscape as possible when water Hydrozoning is locating plantssustainable landscape by planning conservation is desired. Generally, according to a landscape’s differingfor water conservation, choosing low-water-use hydrozones are levels of shading, soil evaporationappropriate plants, improving the located away from the most traveled rates, and exposure to ambientsoil, establishing plants properly, areas of the landscape, but this weather conditions. Early in the designmulching, fertilizing correctly, and is not a requirement. Moderate- process, divide the landscape intowatering efficiently. water-use hydrozones should include low-, moderate-, and high-water-use established plants that only require www.aces.edu
  2. 2. irrigation every 2 to 3 weeks in the Decide which plants should the soil dries. These polymers comeabsence of rainfall or when they be watered first, second, and third, in plastic containers and look likeshow visible signs of stress, such as considering plant value, replacement small white crystals; however, thewilted foliage and off-green color. costs, time to grow a comparable addition of high rates of limestoneHigh-water-use hydrozones should plant, and which ones are significant or fertilizer retards uptake bybe limited and should be strategi- to you. One essential feature of these polymers, though the correctcally located for high impact and a water-efficient landscape is the application rate and the longevity ofeasy access, such as areas around gardener’s judgment on when irriga- the polymer in the soil is debated.patios, decks, pools, or entryways. tion is needed as opposed to relying Considering this in addition to the As a starting point, 10 percent or on an automated timer. high cost of the polymers currentlyless of the total landscape should be makes recommending thesezoned for high water use, 30 percent Soil Improvement materials difficult.or less for moderate water use, and 60 Preparing the soil thoroughly The best time of year to preparepercent or more for low water use. helps ensure good root growth; a previously undisturbed soil is in the Plants vary tremendously in plant with deep, extensive roots fall because it allows time duringdrought tolerance. Many native can withstand periods of drought the winter for incorporated organicplants, once established, often better than plants with shallow roots. matter to decompose and for slowlyrequire little supplemental water or Research has shown that digging a available amendments such as lime-maintenance, but don’t assume that wide planting hole or tilling the soil stone to release. To begin, have a soilall native plants are drought tolerant deeply improves the structure of the test done and add the recommendedor suitable for home landscapes. soil and results in rapid plant estab- slowly available amendments. Do When available, incorporate lishment and better root growth. not add recommended water-solublenative wooded areas into the land- Organic matter dramatically granular fertilizer until spring.scape and blend these areas with the improves most of the different kinds Soils, particularly clay soils,planted portions of the landscape. of soils in Alabama. If the soil is should be dry enough to till, but notRemove weedy or undesirable under- fine clay, choose a coarse-textured too dry. To determine if the soil isstory plants to create more open organic matter such as aged pine dry enough, pick up a handful andareas. It may be necessary to remove bark to increase aeration in the soil. squeeze it. If the ball of soil fallssome canopy trees to reduce compe- This product is available at garden apart when poked, the soil is drytition and improve the health of centers in bags, usually labeled as enough. If it stays in a ball, the soil isremaining trees. Large canopy trees soil conditioner. If the soil is sandy, too wet for tilling.should be strategically placed to keep add fine-textured organic matter for When planting in a large area,the landscape cooler and reduce water-holding capacity. Compost, such as a bed or border, improvewater loss while providing a comfort- humus, and top soil are fine-textured all of the soil at one time. To begin,able living environment. In planted products. Peat moss is another alter- mark off the area that will be tilled.areas, it may be tempting to position native that has a high water-holding Scoop up the existing vegetation toplants close together so they are capacity. It degrades slowly in the remove it. Applying a broad spec-more visually appealing when young, soil, but it is expensive. Peat moss trum postemergent herbicide 7 tobut drastic pruning likely will be is available in bags or compressed 10 days before tilling will make thisneeded as plants approach maturity, bales; compressed bales usually are easier and kill aggressive perennialwhich increases water use and plant the best deal. Composted animal weeds. Apply 4 to 6 inches of organicstress. Learn the expected mature manure is also available in bags. matter, broadcast soil amendmentssize of the plants to be included and Animal manure decomposes rapidly evenly over the area, and incorporateprovide them with sufficient space. in soil, but it does provide plants them uniformly to a 12-inch depth. Windbreaks help keep the plants with nutrients and is inexpensive. Start at one end with the tiller andand soil from drying. Use trees, Water-absorbing hydrophilic go across the soil, one row at a time,informal hedges, shrubs, or tall orna- polymers are designed to be mixed while removing rocks and othermental grasses as natural windbreaks. with soil and act as artificial reser- debris. If the tiller cannot penetrate voirs that release water to plants as deeply into the soil, use a shovel to2 Alabama Cooperative Extension System
  3. 3. turn the soil over. The goal is to turn Bare root plants should be evaporation by up to 70 percentthe soil over a shovel length deep, planted in early spring after the when compared to bare soil. In addi-not to break up the clumps; the tiller coldest weather is over, but before tion to water retention, mulches havewill do that. Next, till the soil in the new growth starts. Whether benefits that create an improved soildirection perpendicular to the first purchased from a local nursery or environment for root growth that, indirection and go across the soil as by mail order, it is best to establish turn, improves a plant’s drought toler-before. When the tilling is done, rake the plant in the landscape as soon ance. These benefits include retardingthe soil smooth and apply a generous as possible. To start, remove the germination of aggressive weed seedslayer of mulch. packing material and soak the roots that compete with ornamental plants in tap water for 4 to 6 hours. Make for water, keeping the soil coolerPlanting a mound of soil in the middle of the in summer and warmer in winter, If you’re not planting in a large hole and spread the plant’s roots out preventing soil erosion and compac-area all at once, but simply adding evenly over the mound. Do not set tion, improving soil structure andplants to an existing border or in turf, the plant too deep. fertility, encouraging microorganismplant trees and shrubs in individual The soil removed from the hole and earthworm proliferation, andholes. Dig the hole two to three times is used to backfill around the root giving an attractive, neat appearancewider than the root ball or container ball. No amendments to the backfill to the landscape. Mulches do absorband about as deep as the height of are recommended when planting water from overhead irrigation so,the root ball. Roughen the sides and trees and shrubs in individual holes. when you water, make sure the waterbottom of the hole with a pick or When backfill soil is enriched with penetrates through the mulch andshovel so that roots can penetrate amendments, the roots of plants reaches the soil.the soil. Water the plant well; it can tend not to grow beyond the isolated Probably the most widely usedbe difficult to rewet a dry root ball environment of the planting hole into mulch for home landscaping inonce it is in the ground. To remove native soils. This leads to weak and Alabama is pine straw and pinethe plant from the container, lay the unstable roots. When filling in with bark. These materials are availableplant on its side with the container soil around the roots, lightly tamp at garden centers and mass marketend near the hole. Hit the bottom the soil to collapse air pockets or add stores in convenient-to-handle units.and sides of the container until the water to help settle the soil. However, obtaining large quantitiesroot ball loosens. If roots are growing Remember, the goal is to provide may necessitate paying a deliveryin a circular pattern around the root plants with a moist, well-drained, and charge or hiring a trucking company.ball, loosen them by hand or slice well-aerated soil environment so they An advantage of pine straw is it looksthrough the roots with a knife. This will develop an extensive root system good in the landscape, but it decom-may appear harmful to the plant, but capable of withstanding periods of poses fairly quickly and may needit actually encourages new growth drought. re-application annually. Generally,while allowing water to move more one bale of pine straw covers 50freely into the root ball. For root balls Mulch square feet when applied to a 5-inchwrapped in burlap, remove the string depth; however, pine straw bales are Often, lessons in sustainableor wire holding the burlap to the root not always a consistent size in the landscape practices can be takencrown. On large trees, it may not be marketplace. Fine-textured mulches, from what occurs in nature. Manypractical to remove all the burlap, such as pine straw, retain more mois- forests in Alabama have the samebut pull away the top one-third. ture than coarse mulches. On sloping dominant feature: an abundance ofRemove plastic wrapping completely sites, pine straw stays in place better accumulated forest-floor litter thatfrom root balls. Place the root ball than most other mulches and helps conserves soil moisture and recyclesin the hole with the top of the root control erosion. nutrients back to the plants. Applyingball (where the roots end and the a 3- to 5-inch layer of an organic Pine bark should be purchased intrunk begins) ½ to 1 inch above the mulch to all nonturf, planted areas a coarse mulch grade. Fine grade pinesurrounding soil. Lay a board across in the landscape helps the soil retain bark does not suppress weeds verythe planting hole to check the depth water and can reduce losses from well and can float away during heavyof the plant. rain. Pine bark looks good in the Drought-Tolerant Landscapes for Alabama 3
  4. 4. landscape and does not decompose as cover the entire surface with mulch, excess runoff and shallow penetrationrapidly as pine straw, but costs more. except within 8 to 10 inches of the into the soil. Hand watering is anOne cubic yard (fourteen 2-cubic-foot trunk of trees or shrubs. In the case of efficient way to water when using abags) of bark mulch covers 100 square trees or shrubs located in turf, mulch hose-end water breaker or a sprayfeet to a 3-inch depth. under the entire canopy of the tree nozzle to deliver water slowly. Shredded hardwood products are extending well beyond the drip line Efficient irrigation should deliveralso good mulches because they mat if possible, but do not pile mulch water no faster than the rate the soiltogether and are less likely to float against the trunk or mulch within a can absorb it. Soil types and texturesaway than chips. Occasionally, wood few inches of the trunk. This space play an important role in how muchchips are available as a by-product of will allow for air circulation around water soil can hold and how quicklylumber operations. Grain straw is the the base of the plant and help avoid soil can be irrigated. For example,stem of grain crops, typically wheat, disease or insect problems. one inch of water applied to thegathered and bailed after the grain is surface of sandy soil may penetrateharvested; it has many of the same Efficient Watering 10 inches deep, but only penetratesproperties as pine straw. Be careful Numerous public awareness 6 inches deep in a silt loam soil, orabout purchasing bails of hay to use as surveys have found that homeowners only 4 inches deep in clay loam soil.mulch. Hay often contains grass and are unaware of the water needs of Irrigating the entire root zone of plantsweed seed that could create a weed landscape plants and often overwater growing in heavy soil takes longerproblem in the landscape. Landscape them. In addition, overhead sprinkler than for plants growing in lighterfabrics can also be used under mulch irrigation systems installed in home soil. Sandy loams may absorb 0.5 toto conserve moisture, discourage landscapes frequently have automated 3 inches of water per hour while clayweeds, and enhance erosion control. controllers that require little involve- loams may absorb only 0.1 to 0.5Be aware that all organic mulches ment on the part of the homeowner inches of water in the same amountdecompose, shrink in volume, and and encourage a set-it-and-forget-it of time. Table 1 has the time requiredneed replenishing regularly. approach. This wastes water, costs for irrigation water to infiltrate up to Obtaining sufficient quantities of money, and may lead to surface water 6 inches deep in sandy loam or claymulch can actually be an exercise in or groundwater contamination by loam soil. Moderately moist, clay loamrecycling if you are willing to do a fertilizers or pesticides. soil requires twice as long to water aslittle networking and have access to The goal of water-efficient sandy loam soil, but, when the claya pickup truck for hauling. Instead landscapes should be to deliver an loam is severely dry, it may requireof raking up autumn leaves and adequate amount of water to the root 3 to 4 times as long. The importantdisposing of them, use the leaves zone of plants just before they experi- point is, before you water, dig downto mulch nonturf, planted beds and ence water stress. When irrigation is and determine if the soil is dry and toaround trees in the turf. If leaves used, water should be applied effi- what extent. Don’t gauge water needsare still left over, consider starting a ciently and effectively to make every on soil surface appearance, thencomposting program. drop count. At one extreme, gardeners check the progress of irrigation peri- Find organic leftovers from the often apply too little water frequently, odically to determine when sufficientagricultural community to use as causing shallow root growth leading water has been applied.mulch. These leftovers, such as peanut to more rapid plant stress underhulls, pecan hulls, or even animal drought or hot conditions. At the Plant Establishmentbedding, are usually available at no or other extreme, gardeners often deliver No matter how drought tolerantlow cost. water too rapidly or run irrigation for a plant is reported to be, it will not Apply at least 3 inches of nonset- too long resulting in water runoff and, be unless a sufficient root systemtling material, such as pine bark, or depending on the soil type, water- develops. For this reason, plants6 inches of material that settles after logged soil conditions. Also, be careful transplanted from containers requirea rain, such as pine or grain straw. when hand watering because water is a period of careful establishmentIn the case of a bed or border where often delivered too quickly for the soil watering; after all, their roots onlyall the soil is prepared at one time, to absorb resulting in wasted water as extend to the limits of the container,4 Alabama Cooperative Extension System
  5. 5. and they are growing in a mix helps prevent moisture loss. Check need establishment care for thedifferent from the soil in which they the moisture in both soil types entire first growing season. However,are planted. Because of this interface at least once a week during the there are exceptions. For example,between soil types, water does not establishment period to see if water camellias, mountain laurel, and manymove readily between the different is required. When the soil is dry, native azaleas are drought tolerantmedia. Therefore, it is important to watering slowly and deeply encour- once established, but because theirapply water to both the container ages a more extensive root system roots grow slowly, they need 2 yearsmix and the surrounding soil during than frequent shallow watering. of establishment care to achievethe establishment period. Roots grow Fall planted trees, shrubs, vines, drought tolerance. For this reason,in soil only where there is moisture, ground covers, and herbaceous peren- camellias, mountain laurel, andand unless both media are moist, nials have demonstrated increased native azaleas are not listed in thethe roots may never grow out of the ability to survive moderately low tables, but include Camellia japonicaoriginal container mix. Container moisture levels the following ( Japanese camellia), Camelliamixes also dry much faster than growing season when compared to sasanqua (Sasanqua camellia),the surrounding soil. Both media those transplanted in the spring or Kalmia latifolia (mountain laurel),should be adequately moistened to summer. Cool fall temperatures are Rhododendron alabamanse (Alabamaprevent newly installed plants from less stressful to plants than the heat azalea), Rhododendron austrinumbeing injured or dying of drought, of late spring and summer because (Florida flame azalea), Rhododendronbut be careful not to overwater; do the foliage loses less water. Plants canescens (Piedmont azalea),not water if both soils are moist. established during fall require less Rhododendron flammeum (OconeeMany gardeners want to water by frequent irrigation and are less likely azalea), Rhododendron pericly-a calendar that more often fits their to suffer heat-related stress than menoides (Pinxterbloom azalea),schedule rather than the needs of those planted in spring and summer. Rhododendron prunifolium (plumleafthe plants. By checking soil moisture As winter approaches, aboveground azalea), and Rhododendron vaseyifrequently, you can become in-tune portions of the plant stop growing (pinkshell azalea) for those willingwith the rate of soil drying and more and go dormant soon after planting to make the effort of establishment.accurately predict when a plant resulting in less demand on the roots After the establishment period,needs water. for water. Roots, on the other hand, gradually reduce watering frequency For plants installed in individual do not go dormant and continue to during dry spells to acclimate plantsplanting holes, construct a berm 4 to grow all winter long. So when spring to drought conditions.6 inches high around the perimeter arrives, a healthy, well-developed Established trees and large shrubsof the planting hole to help funnel root system is in place to help the generally have deeper, more extensivewater to the roots, then fill the plant adapt better to summer stress. roots than other landscape plantsberm with water several times to Trees and shrubs generally and can extract soil moisture evencompletely saturate the soil and require 9 to 10 weeks of establish- when the soil surface appears dry.establish good contact at the interface ment care when planted in the The majority of tree and shrub feederbetween the container mix and soil. late fall or early winter, but those roots (those that take up water andMulching newly established plants planted in the spring or summer nutrients from the soil) are in the top Table 1. Time Required for Irrigation Water to Infiltrate Up to 6 Inches Deep in Sandy Loam or Clay Loam Soil Inches (soil depth) Sandy loam (hours) Clay loam (hours) 1 2 4 2 4 8 3 6 10 4 8 12 5 10 14 6 12 16 Drought-Tolerant Landscapes for Alabama 5
  6. 6. 10 to 12 inches of soil and extend as tolerate constantly wet soils well. Porous best advice is to keep the system asmuch as one and a half to two times wall hose or drip irrigation systems can simple as possible and try to wet onlythe canopy diameter. To be most provide adequate water more efficiently those areas where water can be takeneffective, apply water in this area and than sprinkler systems can. up by the roots of desired plants.to this depth. However, trees partly When planning drip irrigationor completely enclosed by large areas Drip Irrigation for watering trees and large shrubs,of surface concrete or asphalt have Using irrigation water efficiently consider using microsprinklermore limited access to soil moisture requires proper selection of irrigation emitters that wet the soil over aand should be watched closely for methods for the plants and for each larger area and provide more evensigns of water stress. Very large, old hydrozone of the landscape. Drought- watering. Simple drip emitters restricttrees are often more prone to loss tolerant plants should get no more the soil wetting pattern and aredue to drought because of age and water than they need to look good, primarily suitable for small trees andaccumulated stresses, but the impact and water should be prevented from shrubs in borders. It is generally bestof a drought may not be evident until splashing onto concrete walkways or to design a system with a few morethe next growing season. Be more other areas where it is not needed. emitters than you think necessarywatchful for the watering needs of Drip irrigation systems allow slow to allow insertion wherever water isolder trees. water penetration into the root zone needed. The appropriate number of Trees and large shrubs isolated with minimum evaporation or surface emitters per plant and flow rate perin turf should be watered inside and wetting. Often, 30 to 50 percent less emitter depends on the size and typejust outside the drip line and may water may be used with these systems of plant. Generally, the larger therequire water only during periods of when compared to sprinkler irrigation. plant, the more water it requires and,limited rainfall or when they show Drip systems may be as simple as thus, more emitters are required.signs of stress. A temporary system, porous wall hoses that can be moved Drip irrigation systems are usuallysuch as a soaker hose, may be all around the landscape or left in place installed on top of the ground andthat is required for these plants. hidden under mulch for small applica- concealed beneath mulch. ThisIndividual lengths of soaker hose can tions or more extensive systems can makes the system easy to install andbe purchased with brass fittings that be installed using perforated flat protects the plastic components fromeasily attach to any hose or hose bib. tubing or emitters for larger areas. A ultraviolet light degradation whenIn foundations or borders, however, it variety of kits and parts to construct exposed to sunlight. However, theis more convenient to water the entire a system are readily available for the distribution pipes can also be buriedarea, therefore, an irrigation system is do-it-yourself gardener or a system 4 to 6 inches beneath the soil surfacemore efficient. can be installed by a landscape irriga- with the microtubes protruding above Bedding plants, herbaceous peren- tion company. the surface. Extend the microtubes atnials, and ground covers are usually Drip irrigation applies water least 6 inches above ground to allowsmall when planted and have small root from flexible ⅜- to ¾-inch-diameter easy inspection and to prevent dirtsystems to start with. These plants need polyethylene distribution pipes to from back-siphoning into the emitters3 to 4 weeks of establishment watering emitters at the ends of microtubes (⅛ and clogging the system. As a startingand may have to be watered more to ¼ inch), flat perforated tubing, or point, an emitter system may need tooften than trees and shrubs to ensure round porous wall hose (soaker hose). be run about three times per weekan adequate water supply. Check the Several types of drip irrigation systems for 4 hours each time during very drysoil with a trowel or spade to the depth can be adapted to suit a variety of weather to meet the water needs ofof the expected root zone. Moisten the applications, from watering individual the plants. Keep in mind that someentire root zone just before the plants trees and shrubs to beds of annuals, species require more water thanshow signs of water stress. If the plants herbaceous perennials, ground covers, others. Consider this when planningare allowed to wilt severely a few times, or mixed borders. Because so many emitter installation.growth can be stunted and flower different types of drip irrigation For watering annuals, perennials,production reduced. Be careful not to components are available, choosing and ground covers, it is usuallyoverwater because most bedding plants the best system for a particular appli- necessary to irrigate a solid area. Thisand herbaceous perennials do not cation requires some planning. The6 Alabama Cooperative Extension System
  7. 7. can be accomplished by spacing emit- perform well when fertilized every • Remove weeds promptly becauseters 12 to 18 inches apart to achieve other year. The exceptions are annual they compete for valuable water.a uniform wetting pattern or using flowers and many roses that require • Avoid summer pruning exceptperforated tubing or porous wall pipe annual fertilization to grow and to remove dead, diseased, orat the same spacing. In sandy soils, flower well. damaged wood because itthe lines need to be closer together Fertilizers with a high nitrogen encourages new vegetativethan in fine-textured clay soils. In percentage (first number in a fertilizer growth and inhibits root growth.bedding plant beds, the drip lines can analysis) relative to phosphorus and • Prune plants when they wiltbe laid aside for soil preparation and potassium percentages (second and during severe drought stress toreplaced afterward. Cover perforated third numbers in a fertilizer analysis) save them. Remove about one-tubing or porous pipe under mulch to tend to stimulate excessive vegetative third of the canopy to reduce theprevent ultraviolet light degradation growth. When shoot growth increases, leaves’ demand for moisture.from exposure to sunlight. root growth decreases, so the roots • Maintain the irrigation system to An alternative method of watering are less efficient at extracting moisture prevent leaks that waste water.uses small sprinkler heads called from the soil. Therefore, look for a • Be conscious of the changingmicrosprinklers, instead of emitters. All fertilizer with a nitrogen percentage water needs of plants throughother components are identical to drip equal to or slightly less than the phos- the season, and change irrigationirrigation, including the polyethylene phorus and potassium percentages practices accordingly.distribution pipes. Microsprinklers and then apply it at a low rate. The • Capture rainwater or recycle watercover an area 3 to 12 feet wide and rate information should be printed on when possible. Rain catchmentare used for trees and shrubs or beds the fertilizer container. Just choose the systems are available.requiring complete coverage. Do not low end of the prescribed rate range.combine microsprinklers with drip If the rate is not provided, a low rate • Adjust irrigation practicesemitters in the same irrigation zone. would be 1 pound of actual nitrogen according to sun exposure.Microsprinklers are not as efficient per 1,000 square feet. To calculate the North and east exposures needas drip emitters because some water application rate, divide the nitrogen less water than south or westevaporation occurs, but they do percentage (the first number) in the exposures.provide an economical method of analysis into 100. The application rate • Avoid large areas of light-coloredachieving uniform watering. using a 12-12-12 garden fertilizer is gravel because it reflects heat calculated as follows: 100 ÷ 12 = 8.3 and can create a microclimateFertilization pounds per 1,000 square feet. resulting in greater water loss The best time to fertilize plants in from surrounding plants. One goal in a water-efficientlandscape is to manage vegetative the landscape is late winter just before • Consider converting low-traffic turfgrowth so that plants make reason- spring growth begins. Fall fertilization areas to more drought-tolerantable progress toward maturity, but is not recommended because it may ground covers. Turfgrassesgrow very little at maturity. At matu- decrease winter hardiness and high generally require more frequentrity, plants should be fertilizered only rainfall during typical Alabama winters watering and maintenance thanenough to maintain plant health. The wash fertilizer out of the root zone. most other landscape plants.main concern is to avoid overfertil- Lastly, do not fertilize plants during • Terrace steep slopes to reduceizing because it encourages rapid, a drought period because fertilizers runoff erosion and slow watersoft growth that is more susceptible are composed of nutritive salts that movement so the soil can absorb it.to drought. Most established, healthy can dehydrate and burn roots in the • Avoid using narrow strips of turf,trees and shrubs only need fertilizer absence of adequate water. hard-to-maintain corners, andonce every 2 to 3 years while most isolated islands of grass thatestablished herbaceous perennials Additional Tips need special attention. • Water before the soil dries out on clay soils. Once dry, clay soils are extremely difficult to rewet. Drought-Tolerant Landscapes for Alabama 7
  8. 8. Drought Tolerance therefore, some decrease in growth Plants selected for inclusionin Plants and flowering can be expected during in the tables are the consensus periods of limited moisture. Severe of horticultural professionals in Drought tolerance is a difficult drought can increase insect or disease the Department of Horticultureplant characteristic to define because it incidence, decrease leaf size and at Auburn University, curatorsdepends not only on a plant’s inherent number, and cause an overall decline of the Huntsville and Mobileability to conserve water internally in growth rate and plant vigor. High Botanical Gardens, and selectedduring times of shortage, but also on temperatures and wind, heat and light agents in the Alabama Cooperativehow well the plant has established a reflection from nearby hard surfaces, Extension System from differentroot system and how well the plant can or high fertilization can increase the regions of the state. The majorityadapt to environmental stresses other potentially damaging effects of low of the plants in the tables arethan water availability, such as adverse moisture on plant growth and survival. hardy over a wide portion ofsoil conditions, high temperature, high Regional differences in drought toler- Alabama; however, plants arelight intensity, variable wind speed, and ance in a plant are particularly evident included that may only be hardyrelative humidity. Drought tolerance because of varying adaptability to the in the northern or southern one-does not mean the plants prefer hot, largely north to south environmental quarter to one-half of the state.dry weather or that they will not be gradient in Alabama. Plants listed in When making plant selections,adversely affected by extended dry Tables 2 to 10 perform well in the you should consider adaptabilityweather without some supplemental landscape with occasional irrigation to your area of the state. Many ofirrigation. Many plants are drought (every 2 to 3 weeks during drought) or the species are also represented intolerant because they can shut down irrigation only during severe drought, the trade by numerous cultivars,growth during extended drought, but not regular irrigation. which may vary in drought toler- ance. These lists should not be construed as complete.8 Alabama Cooperative Extension System
  9. 9. Table 2. Large Canopy Trees Scientific name Common name Native* DeciduousAcer barbatum Florida maple yAcer ×freemanii ‘Autumn Blaze’ nAcer leucoderme chalk maple yCarya glabra pignut hickory yCarya illinoinensis pecan yCastanea mollissima Chinese chestnut yCatalpa bignonioides catalpa yCeltis laevigata sugar hackberry yCeltis occidentalis common hackberry yDiospyros virginiana common persimmon yGinkgo biloba ginkgo nGleditsia triacanthos honey locust yJuglans nigra black walnut yLiriodendron tulipifera tuliptree yMaclura pomifera Osage orange yNyssa sylvatica black gum yPistacia chinensis Chinese pistache nQuercus acutissima sawtooth oak nQuercus alba white oak yQuercus geminata sand oak yQuercus lyrata overcup oak yQuercus macrocarpa bur oak yQuercus marilandica blackjack oak yQuercus muehlenbergii chinkapin oak yQuercus nuttallii Nuttall oak yQuercus prinus chestnut oak yQuercus stellata post oak yQuercus velutina black oak ySapindus saponaria var. drummondii soapberry nStyphnolobium japonicum Japanese pagodatree nTaxodium ascendens bald cypress yUlmus parvifolia Chinese elm nZelkova serrata Japanese zelkova n EvergreenCalocedrus decurrens incense cedar nCedrus deodara Deodar cedar yCupressus arizonica Arizona cypress nCupressus sempervirens Italian cypress nJuniperus virginiana eastern red cedar yMagnolia grandiflora southern magnolia yPinus clausa sand pine yPinus elliottii slash pine yPinus glabra spruce pine yPinus palustris longleaf pine yPinus strobus eastern white pine yPinus taeda loblolly pine yPinus virginiana Virginia pine yQuercus glauca blue Japanese oak nQuercus hemisphaerica Darlington Oak yQuercus laurifolia laurel oak yQuercus virginiana live oak yThuja orientalis Oriental arborvitae n * Native to Alabama, y = yes or n = no (introduced) Drought-Tolerant Landscapes for Alabama 9
  10. 10. Table 3. Noncanopy Trees Scientific name Common name Native* Deciduous Acer buergerianum trident maple n Acer truncatum Shantung maple n Amelanchier spp. and cultivars juneberry y Asimina triloba pawpaw y Cercis canadensis eastern redbud y Chilopsis linearis desert willow y Clethra pringlei Mexican sweetspire n Cotinus coggygria common smoketree n Cotinus obovatus American smoketree y Crataegus crus-galli cockspur hawthorn y Crataegus marshallii parsley hawthorn y Crataegus mollis downy hawthorn y Cydonia oblonga fruiting quince n Erythrina ×bidwillii hybrid fireman’s cap n Ilex verticillata winterberry y Koelreuteria paniculata goldenraintree n Lagerstroemia fauriei Japanese crapemyrtle n Lagerstroemia indica crapemyrtle n Magnolia ×soulangeana saucer magnolia n Nyssa sylvatica black gum n Oxydendrum arboreum sourwood y Prunus americana American plum y Prunus angustifolia Chickasaw plum y Prunus ‘Okame’ Okame cherry n Prunus subhirtella higan cherry n Rhamnus caroliniana Carolina buckthorn y Rhus typhina staghorn sumac y Tamarix gallica French tamarisk n Vitex agnus-castus lilac chastetree n Ziziphus jujuba jujube n Evergreen Caesalpinia spp. Bird-of-paradise trees n Cupressus arizonica ‘Carolina Sapphire’ Arizona cypress n Eriobotrya japonica loquat n Ilex ×attenuata ‘Savannah’, ‘Foster’ holly n Ilex ‘Nellie R. Stevens’ Nellie R. Stevens holly n Ilex opaca American holly y Ilex vomitoria yaupon y Lithocarpus henryi Henry tanbark oak n Loropetalum chinense Chinese fringetree n Myrica cerifera southern wax myrtle y Prunus caroliniana Carolina cherry laurel y * Native to Alabama, y = yes or n = no (introduced)10 Alabama Cooperative Extension System
  11. 11. Table 4. Deciduous Shrubs Scientific name Common name Native* Aesculus parviflora bottlebrush buckeye y Aesculus pavia red buckeye y Anisicanthus wrightii var. aurea desert honeysuckle n Aronia arbutifolia red chokeberry y Asimina parviflora smallflower pawpaw y Berberis ×mentorensis Mentor barberry n Berberis thunbergii Japanese barberry n Callicarpa americana American beautyberry y Callicarpa japonica Japanese beautyberry n Calycanthus floridus sweetshrub y Caryopteris ×clandonensis bluebeard n Castanea pumila Allegheny chinkapin y Chaenomeles speciosa flowering quince n Deutzia gracilis slender deutzia n Deutzia scabra fuzzy deutzia n Diervilla rivularis Georgia bush honeysuckle y Diervilla sessilifolia southern bush honeysuckle y Exochorda racemosa common pearlbush n Ficus carica fig n Forsythia ×intermedia border forsythia n Fothergilla gardenii dwarf fothergilla y Hamamelis vernalis vernal witchhazel n Hamelia patens hummingbird bush n Hibiscus syriacus shrub althea n Hydrangea quercifolia oakleaf hydrangea y Ilex decidua possumhaw y Jasminum floridum Florida jasmine n Jasminum mesnyi primrose jasmine n Jasminum nudiflorum winter jasmine n Kerria japonica Japanese kerria n Lespedeza thunbergii Thunberg’s lespedeza n Leucothoe racemosa sweetbells leucothoe y Lonicera fragrantissima winter honeysuckle n Magnolia stellata star magnolia n Philadelphus coronarius sweet mock orange n Physocarpus opulifolius ninebark n Poncirus trifoliata hardy orange n Punica granatum pomegranate n Rhus glabra smooth sumac y Rosa ‘Knockout’ Knockout rose n Rosa ‘Nearly Wild’ Nearly Wild rose n Russelia equisetiformis Coral Fountain Plant n Spirea ×arguta garland spirea n Spiraea ×bumalda Anthony Waterer spirea n Spiraea cantoniensis Reeves spirea n Spiraea prunifolia bridalwreath spirea n Spiraea thunbergii Thunberg’s spirea n Spiraea ×vanhouttei Vanhoutte spirea n Symphoricarpos orbiculatus coralberry y Ungnadia speciosa Mexican buckeye n Vaccinium arboreum sparkleberry y Vaccinium ashei rabbiteye blueberry y Vaccinium elliottii Elliott’s blueberry y Viburnum ×burkwoodii Burkwood viburnum n Viburnum dentatum arrowwood y Viburnum prunifolium blackhaw viburnum y Viburnum rufidulum rusty blackhaw viburnum y* Native to Alabama, y = yes or n = no (introduced) Drought-Tolerant Landscapes for Alabama 11
  12. 12. Table 5. Evergreen Shrubs Scientific name Common name Native* Abelia chinensis Chinese abelia n Abelia ×grandiflora glossy abelia n Acca (Feijoa) sellowiana pineapple guava n Agarista populifolia Florida leucothoe y Aloysia virgata almond verbena y Berberis julianae wintergreen barberry n Berberis ×mentorensis Mentor barberry n Buxus microphylla var. japonica Japanese boxwood n Buxus microphylla var. koreana Korean boxwood n Buxus sempervirens common boxwood n Cassia corymbosa Argentine senna n Cassia splendida fall-blooming senna n Cephalotaxus harringtonia Japanese plum yew n Cotoneaster dammeri bearberry cotoneaster n Cotoneaster horizontalis rockspray cotoneaster n Cotoneaster lacteus brightbead cotoneaster n Cotoneaster microphyllus littleleaf cotoneaster n Cytisus scoparius Scotch broom n Ilex ×aquipernyi brilliant holly n Ilex ×attenuata many cultivars n Ilex cornuta cvs. Chinese Holly n Ilex crenata ‘Compacta’ and ‘Convexa’ only n Ilex glabra inkberry holly y Ilex ×hybrids many cultivars n Ilex latifolia lusterleaf holly n Ilex opaca American holly y Ilex vomitoria Yaupon holly y Illicium parviflorum small anise-tree n Juniperus spp. many juniper species and cultivars n Lonicera fragrantissima winter honeysuckle n Michelia figo banana shrub n Nandina domestica nandina n Nerium oleander oleander n Osmanthus americanus devilwood y Osmanthus ×fortunei Fortune’s osmanthus n Osmanthus fragrans sweet olive n Osmanthus heterophyllus holly osmanthus n Philadelphus coronarius sweet mock orange n Pittosporum tobira pittosporum n Podocarpus macrophyllus Chinese podocarpus n Pyracantha angustifolia ‘Yukon Belle’ Yukon Belle firethorn n Pyracantha coccinea scarlet firethorn n Pyracantha crenatoserrata Chinese firethorn n Pyracantha koidzumii Formosa firethorn n Rhaphiolepis indica Indian hawthorn n Rhapidophyllum hystrix needle palm n Rhododendron indicum southern Indian azalea n Rhododendron obtusum Kurume azalea n Sabal palmetto palmetto palm y Serissa foetida ‘Kowloon’ Kowloon serissa n Sophora secundiflora Texas mountain laurel n Trachycarpus fortunei windmill palm n Viburnum awabuki mirror leaf viburnum n Viburnum luzonicum Luzon viburnum n Viburnum obovatum Walter’s viburnum and ‘Densa’ y Viburnum odoratissimum sweet viburnum n Viburnum ‘Pragense’ Prague viburnum n Viburnum ×rhytidophylloides lantanaphyllum viburnum n Viburnum suspensum Sandankwa viburnum n Viburnum tinus laurustinus n Yucca aloifolia Spanish bayonet n Yucca filamentosa Adam’s needle y Yucca gloriosa mound lily yucca y Yucca recurvifolia soft leaf yucca y * Native to Alabama, y = yes or n = no (introduced)12 Alabama Cooperative Extension System
  13. 13. Table 6. Vines and Ground Covers Scientific name Common name Native* Bauhinia yunnanensis pink orchid vine n Bignonia capreolata crossvine y Campsis radicans trumpet creeper y Campsis ×tagliabuana hybrid trumpet creeper n Clitoria mariana butterfly pea y Clitoria ternatea blue pea vine n Euonymus fortunei ‘Coloratus’ wintercreeper euonymus n Gelsemium sempervirens Carolina jessamine y Juniperus conferta shore juniper n Juniperus davurica Parson’s juniper n Juniperus horizontalis creeping juniper n Juniperus procumbens Japanese garden juniper n Lathyrus latifolius everlasting pea n Liriope muscari lilyturf n Liriope spicata spreading lilyturf n Lonicera ×heckrottii goldflame honeysuckle n Lonicera sempervirens coral honeysuckle y Ophiopogon japonicus mondograss n Parthenocissus quinquefolia Virginia creeper y Parthenocissus tricuspidata Boston ivy n Passiflora incarnata maypop y Quisqualis indica Rangoon creeper vine n Rosa banksiae Lady Banks rose n Senecio confusus Mexican flame vine n Smilax smallii Jackson vine y Thunbergia alata black-eyed Susan vine n Trachelospermum asiaticum Asiatic jasmine n Trachelospermum jasminoides confederate jasmine n Vinca major greater periwinkle n Vinca minor lesser periwinkle n Vitis rotundifolia muscadine y Wisteria frutescens American wisteria y* Native to Alabama, y = yes or n = no (introduced) Drought-Tolerant Landscapes for Alabama 13
  14. 14. Table 7. Annuals or Biennials Scientific name Common name Angelonia angustifolia summer snapdragon Arctotis ×hybrida blue-eyed African daisy Argemone grandiflora showy pricklypoppy Argemone mexicana Mexican poppy Asclepias curassavica bloodflower Begonia ×semperflorens cultorum wax begonia (not in full sun) Berlandiera lyrata chocolate daisy Calandrinia umbellata rock purslane Carthamus tinctorius safflower Castilleja indivisa Indian paintbrush Catharanthus roseus annual vinca Celosia argentea var. plumed or crested plumosa or cristata cock’s comb Celosia spicata wheat cock’s comb Convolvulus tricolor dwarf morning glory Coreopsis tinctoria calliopsis Cosmos bipinnatus tall cosmos Cosmos sulphureus sulphur cosmos Dianthus barbatus sweet william Dracopis amplexicaulis clasping coneflower Eschscholzia californica California poppy Euphorbia marginata snow-on-the-mountain Eustoma grandiflorum lisianthus, prairie gentian Gaillardia ×grandiflora blanket flower Gazania rigens treasure flower Gomphrena globosa globe amaranth Helianthus annuus annual sunflower Helichrysum bracteatum strawflower Leonotis nepetifolia lion’s ear Limonium sinuatum annual statice Melampodium paludosum medallion flower Mirabilis jalapa four o’clock flower Nolana paradoxa Chilean bellflower Perilla frutescens shrubby perilla Portulaca grandiflora moss rose Portulaca oleracea purslane Ricinus communis castor bean (toxic) Sanvitalia procumbens Mexican creeping zinnia Scaevola aemula fan flower Senecio cineraria dusty miller Verbascum bombyciferum nettle-leaved mullein Zinnia angustifolia narrowleaf zinnia Zinnia haageana Mexican zinnia Zinnia marylandica ‘Profusion’ series zinnia14 Alabama Cooperative Extension System
  15. 15. Table 8. Herbaceous PerennialsScientific name Common nameAchillea בCoronation Gold’ Coronation Gold yarrowAchillea filipendulina fernleaf yarrowAchillea בMoonshine’ Moonshine yarrowAgapanthus africanus agapanthusAlyssum montanum creeping basket-of-goldAmsonia tabernaemontana eastern bluestarArmeria maritima common thriftArtemisia spp. wormwoodAsclepias tuberosa butterfly weedAspidistra elatior cast-iron plantAster spp. fall asters (some)Aurina saxatilis basket-of-goldBaptisia alba white false indigoBaptisia australis false blue indigoBaptisia carolina false indigoBaptisia tinctoria wild indigoBelamcanda chinensis blackberry lilyCeratostigma plumbaginoides plumbagoChrysopsis villosa golden asterCoreopsis auriculata ‘Nana’ mouse ear coreopsisCoreopsis grandiflora tickseedCoreopsis lanceolata lance coreopsisCrocosmia ×crocosmiiflora montbretiaCuphea llavea bat face cupheaDelosperma ashtonii Ashton’s ice plantDelosperma cooperi hardy ice plantDelosperma nubigenum orange-yellow hardy ice plantDianthus deltoides maiden pinkDianthus gratianopolitanus cheddar pinkDianthus plumarius cottage pinkEchinacea angustifolia prairie coneflowerEchinacea paradoxa yellow coneflowerEchinacea purpurea purple coneflowerEchinacea tennesseensis Tennessee coneflowerEpimedium spp. epimediumErythrina herbacea coralbeanEupatorium havanense white mist flowerGuara lindheimeri guaraHeliopsis helianthoides false sunflowersHelleborus foetidus bear’s foot helleboreHelleborus orientalis Lenten roseHemerocallis spp. daylilyIris cristata crested irisIris hybrids bearded irisesIris pallida dalmatian irisIris sibirica Siberian irisKniphofia hirsuta dwarf red hot pokerKniphofia uvaria red hot pokerLantana camara shrub verbenaLantana montevidensis trailing lantanaLiatris spicata spike blazing starLinum spp. flaxLychnis coronaria rose campionOenothera fruiticosa sundrop Drought-Tolerant Landscapes for Alabama 15
  16. 16. Oenothera macrocarpa Missouri evening primrose Opuntia compressa eastern pricklypear cactus Perovskia atriplicifolia Russian sage Phlomis ‘Edward Bowles’ hybrid Jerusalem sage Phlomis fruticosa Jerusalem sage Phlomis russeliana Jerusalem sage Phlomis tuberosa tuberous Jerusalem sage Phlox subulata creeping phlox Pycnanthemum virginianum mountain mint Rudbeckia fulgida black-eyed susan Rudbeckia laciniata cutleaf coneflower Rudbeckia maxima great coneflower Rudbeckia nitida shining coneflower Ruellia brittoniana Mexican petunia Salvia greggii Texas sage Salvia guaranitica blue anise sage Salvia leucantha Mexican sage Salvia microphylla baby sage Salvia reptans cobalt sage Salvia texana blue Texas sage Santolina chamaecyparissus lavender cotton Santolina rosmarinifolia green santolina Sedum spp. stonecrop Silene caroliniana wild pink Solidago hybrids ‘Cloth of Gold’, ‘Crown of Rays’ Goldenrod Solidago canadensis Canada goldenrod Solidago rugosa wrinkle-leaf goldenrod Spigelia marilandica Indian pink Stachys byzantina lamb’s ears Verbascum phoeniceum purple mullein Verbascum thapsus common mullein Verbena bonariensis purpletop vervain Verbena canadensis rose verbena Verbena rigida sandpaper verbena Verbena tenuisecta moss verbena Vernonia altissima tall ironweed Veronica prostrata prostrate speedwell Veronica repens creeping speedwell16 Alabama Cooperative Extension System
  17. 17. Table 9. Herbs Scientific name Common name * Agastache foeniculum anise hyssop p Allium schoenoprasum chives p Allium tuberosum garlic chives p Artemisia abrotanum southernwood p Borago officinalis borage a Calamintha nepeta calamint p Eucalyptus cinerae silver dollar tree a/p Foeniculum vulgare fennel p Lavandula angustifolia English lavender p Laurus nobilis bay a/p Lavandula stoechas Spanish lavender p Marrubium vulgare horehound p Matricaria recutita false camomile a Nepeta cataria catnip p Nepeta ×faassenii catmint p Nepeta racemosa Persian catmint p Origanum laevigatum ornamental oregano p Origanum marjorana sweet marjoram a Origanum onites pot oregano p Origanum vulgare wild oregano p Rosemarinus officinalis rosemary p Ruta graveolens rue p Saponaria officinalis soapwort p Satureja montana winter savory p Tagetes lucida Mexican tarragon p Tanacetum parthenium feverfew p Teucrium chamaedrys wall germander p Thymus camphoratus camphor Thyme p Thymus ×citriodorus lemon thyme p Thymus herba-barona caraway-scented thyme p Thymus praecox ssp. arcticus mother-of-thyme p Thymus pseudolanuginosus wooly thyme p Thymus vulgaris garden thyme p Tulbaghia violacea society garlic p* a = annual, p = perennial, or a/p = perennial treated as an annual depending on hardiness zone Drought-Tolerant Landscapes for Alabama 17
  18. 18. Table 10. Ornamental Grasses Scientific name Common name Native* Andropogon gerardii big bluestem y Andropogon ternarius splitbeard bluestem y Andropogon virginicus broom sedge y Bouteloua gracilis blue gammagrass y Briza media quaking grass n Chasmanthium latifolium upland sea oats y Cortaderia sellowiana pampas grass n Eragrostis curvula weeping love grass n Eragrostis elliottii Elliott’s love grass y Eragrostis spectabilis purple love grass y Hystrix patula bottlebrush grass y Leymus arenarius blue lyme grass n Miscanthus ‘Giganteus’ giant silvergrass n Miscanthus sinensis Japanese silvergrass (sterile n cultivars only) Muhlenbergia filipes gulf muhly y Muhlenbergia lindheimeri muhly grass y Muhlenbergia rigens deer grass y Muhlenbergia capillaris pink muhly grass y Nassella tenuissima Mexican feather grass y Panicum virgatum switchgrass y Saccharum ravennae Ravenna grass n Schizachyrium scoparium little bluestem y Stipa gigantea giant feather grass n* Native to Alabama, y = yes or n = no J. Raymond Kessler Jr., Extension Horticulturist, Professor, Horticulture, Auburn University. Acknowledgments. Auburn University: Glenn Fain, Charles Hesselein, Gary J. Keever, Harry G. Ponder, Beth Clendenen, Dee Smith, Kerry Smith, Ken Tilt. The Alabama Cooperative Extension System: Rick Beauchamp, Daniel Porch, Stan Roark, and Jim Todd. The Mobile Botanical Gardens: Marion Drummond. The Huntsville Botanical Gardens: Harvey Cotten For more information, call your county Extension office. Look in your telephone direc- tory under your county’s name to find the number. Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability. ANR-1336 Web Only, New Oct 2008, ANR-1336 © 2008 by the Alabama Cooperative Extension System.