Water Wise Plants
Acacias include a diverse group of arid region landscape plants ranging from trees to shrubs to groundcovers. Acacias offer shade, screening, and spectacular flower shows for your landscape, depending upon the plant selected. They are primarily full sun plants and tolerate a variety of soil conditions. Tree acacias require infrequent, yet periodic deep watering to develop a healthy root system. This is done by watering along the edge of the canopy and not at the base of the trunk. All Australian acacias have modified leaf stems called phyllodes, which are commonly thought to be their leaves, and perform the same function as the leaves.
Agaves are impressive leaf succulents with a wide range of color, texture and size to their rosettes. There are approximately 200 species found throughout the southwest, Mexico and Central America. The bold rosettes are dramatic accents for the landscape that contrast well with the fine texture of desert-adapted trees and shrubs. Agaves are some of the most useful desert plants, tolerant of heat, cold, drought, and poor soil. Agaves, or century plants, take from five to fifty years to finally flower, often with a spectacular flowering stalk. After blooming, the plant slowly dies. However, they often produce offsets, seeds or bulbils (plantlets).
Because of their sharp leaves and the large size of some agaves, avoid placing close to walkways, windows, or patios. Medium to small agaves work well in containers or combined with groundcovers and wildflowers for colorful landscape combinations. They are best suited for fall and late winter planting. Irrigation should be deep and infrequent for best plant health.
Aloes are striking succulents from southern and eastern Africa that offer some of the best color for Arizona landscapes with their impressive and long-lasting show of flowers during the winter and early spring. Aloes have numerous forms ranging from low groundcovers to tree-like species. Small clustering forms work well in containers and the tree forms work well as accents or planted in mass, particularly with groundcovers and wildflowers. Their tubular flowers borne on long flowering stalks range in color from yellow to coral to intense red-orange and attract hummingbirds. The sharp-tipped leaves have pale to reddish brown teeth along the margins. The rosettes do not die after flowering, and many species of aloe produce offsets that spread to cover large areas.
Aloes have a wide range of hardiness, but most species suffer some damage to their rosettes and flower stalks at 24 degrees Fahrenheit. They are attractive in containers where they can be moved to provide protection from frost or sunburn. They can take full winter sun and are heat and drought tolerant, but look better in the summer with partial or filtered shade and occasional watering. Aloes are tolerant of most soils, but require good drainage. Aloes are very easy to grow and require little maintenance other than removing dead flower stalks and dividing crowded clusters. Although largely pest-free in our area, they can be affected by the aloe mite which causes unsightly growth on the flower stalk and leaves. Prompt removal of the affected plant parts will prevent the spread of this problem.
Caesalpinia (Bird of Paradise)
Casesalpinias make the landscape come alive with color. Their large bright flowers provide vibrant color for long periods of time. The shades of yellow, fiery red, and orange contrast with the feathery foliage.
Commonly called bird of paradise, they range in size from medium shrubs to small trees. They thrive in the desert heat and can survive on little supplemental irrigation. Provide deep watering every two weeks while blooming in order to prolong flowering and keep plants healthy.
Bird of paradise is tolerant of most soil conditions but prefers well drained soils. Chlorosis can occur in heavy soils but is easily treated with iron chelate. The deciduous varieties can be pruned back severely during the winter when they are dormant, and new growth will occur in the spring. This pruning will also keep the form more round and compact. The seed pods should not be eaten.
Both hummingbirds and butterflies are attracted to the blooms.
The name calliandra refers to the beautiful stamens which make up the tufted or ball-like flowers. Their colors, ranging from pale pink through deep red, are indeed beautiful. These small to medium sized shrubs produce their flowers against a backdrop of finely divided, lacy-looking foliage. Calliandras can be used in a wide variety of landscape situations. Fairy dusters are a natural for wildlife gardens, adding a bright spot of color and a food source for hummingbirds. Calliandras are also well suited to a more traditional yard, where their nearly evergreen foliage and delicate blossoms provide color and interest. Fairy dusters require very little pruning to maintain their naturally rounded form, and are extremely drought tolerant, and bloom profusely in full sun. They tolerate most soil types and recover quickly if damaged by frost.
Palo verdes are native to the arroyos and foothills of the southwestern deserts and Mexico. Their unique green to blue-green bark and branches carry on photosynthesis, even when their small leaves are not present. In the spring these trees are covered with masses of bright yellow flowers, providing some of the most outstanding spring color in our deserts.
Palo verdes thrive in the high summer temperatures, but vary in their cold-hardiness. They prefer full sun, good drainage, and an occasional deep soak during their summer growing season. Cercidium tend to sunburn if pruned during the summer. These are multi-trunked and pruning should be done only to enhance form. Avoid planting palo verde trees in turf areas, where they are easily damaged by power mowers and string trimmers. Once established in a landscape, weaning these trees off regular irrigation helps control tree size, manage growth and limit pruning without compromising tree vigor or flowering. The following palo verdes are some of the most popular, colorful and low maintenance trees available.
Desert willow is a fast-growing tree reaching up to 25 feet with spectacular trumpet –shaped flowers and glossy green, willow-like foliage. Chilopsis linearis is native to the southwestern United States and northern Mexico, and is commonly seen in dry washes from 1500 to 5000 feet. The fragrant orchid-like flowers in varying colors attract hummingbirds. Desert willow blooms in clusters from May through October. In winter, this tree is deciduous which reveals its interesting branch structure.
Daleas are a diverse group of plants that have delicate texture, provide wonderful winter to early spring color, and tolerate our hot summers. The nearly 200 species of these plants include trees, shrubs and groundcovers, many of which are native to the deserts of the Southwest. Most of the recent introductions of daleas are groundcovers or shrubs that range in height from 1 ½ to 5 feet in height. The pea-like flowers vary from purple to rose to yellow, and attract pollinating bees and butterflies. A variety of birds like quail, dove, and finches enjoy the seeds.
Ebenopsis ebano (Texas Ebony) - (formerly Pithecellobium flexicaule)
Texas ebony is native to the lowland regions of the Gulf of Mexico from southern Texas to northeastern Mexico. The highly ornamental, glossy, dark green foliage is its most striking feature. This popular small to medium tree has flexible, zigzagged branches, and fragrant catkin-like spring flowers. The dense canopy is evergreen in lower desert regions.
Texas ebony is slow-growing, reaching 25 feet tall and 20 feet wide. This versatile tree is valued for both its specimen quality in patios and gardens, or as a screen or barier plant. The thorns provide security where needed. When used for patios and gardens, its thorns must be taken into account in its placement. With careful pruning, the canopy can be raised to form a patio tree.
This group of evergreen plants comes from the semi-arid to arid regions of Australia. In fact the translation of the scientific name, eremos, means desert or lonely place. The eremophilas, or emu bushes, grow in a variety of soil types very similar to those we have in the southwest. Most are very drought tolerant, surviving long periods without water.
The flowers of the various varieties of eremophila range from white, yellow, violet, purple, pink and red. The throats of the tubular flowers are sometimes spotted, but always attract hummingbirds and other nectar feeders.
The strong vertical form of hesperaloe with its spectacular flower spilkes makes this clumping, evergreen perennial an ideal accent plant for landscapes. While not a true yucca or aloe, it is related to yuccas and agaves, and like its relatives, is a carefree, non-demanding plant. Hesperaloes are extremely hardy, tolerating both heat and cold well in our climate. Hesperaloes prefer a sunny location and mature more rapidly with well-drained soils, but will adapt to heavy soils if not over-watered.
Hummingbirds are attracted to the tubular flowers that occur in several colors, ranging from creams to reds. Its long, thornless, sword-like leaves work well with gray-leaved shrubs, such as leucophyllum, and look striking when emerging from a patch of flowering groundcovers or wildflowers. Established plants provide long-lasting summer color. This plant adapts to annual rainfall, but will look best with minimal supplemental irrigation during extended hot, dry periods. Fall and winter are ideal times for planting.
Angelita Daisy is one of the best perennials for year-round color here in the low desert. It's sunny yellow, daisy-like flowers bloom profusely in the spring, and continue to provide a spash of color during the rest of the year.
A great choice for tight spaces, this compact plant will form a clump to 1 foot tall by 1 or 2 feet wide. Its slender dark green leaves compliment the 1 inch flowers which grow above the foliage on leafless stems. Angelita Daisy looks good as a border plant, but creates the greatest impact planted on 1 foot centers to create a flowering groundcover. Try using this attractive plant next to purple verbena for a dazzling color combination.
Plant Angelita Daisy in full sun. Once established, watering every week to 10 days in the summer will keep it looking its best. It will reseed occasionally in landscapes where it finds adequate moisture, but is not invasive.
This tough desert native occurs naturally in Arizona, New Mexico, Colorado, Nevada and southern California.
With long, colorful, tubular flowers, justicias are a hummingbird's delight. Flower colors range from yellow to deep red. Justicias' green foliage contrasts well with gray desert-adapted plants. Native to tropical and sub-tropical regions, they can be used in many types of landscapes. These evergreen shrubs bloom throughout the year, inviting hummingbirds into the urban wildlife garden.
If plants are damaged by frost, become leggy, or have reduced flower production, they may be rejuvenated by pruning to the ground after the last frost in early spring. They recover rapidly in warm weather and flourish with infrequent, deep watering.
Texas sages are among the most reliable and fool-proof of the low water use plants available in Arizona. Fifteen years ago, there was only one option for Texas sage (Leucophyllum frutescens) available local nurseries. The past few years have brought many new species and varieties into cultivation. These evergreen shrubs are native to Texas and Mexico, and perform well in our deserts with little maintenance. These shrubs require full sun and good drainage. This genus is now available in a wide range of mature sizes, and when the proper Texas sage is selected, no pruning is required...Selective pruning can be performed if desired to maintain shape (do not shear). All of the Texas sages tolerate temperatures down to 10 degrees Fahrenheit, as well as thrive in our summer heat.
Leucophyllums can be used in a wide range of landscape situations, including focal points, visual and wind screening, accents, and wildlife habitat. With the onset of the summer monsoons, leucophyllum explodes in burst of color, giving it the nickname barometer plant. They can survive on little to not supplemental watering except during periods of extreme drought, and can die if overwatered. While some Texas sages mature at 6 or 8 feet, listed below are smaller varieties that are suitable for home landscapes.
These spectacular, non-invasive, ornamental clumping grasses are versatile and require very little maintenance. Muhlenbergias are native to the southwestern United States and northern Mexico at elevations of 2500’ to 7000’. With over 125 species, this large and diverse group can be used as a vertical specimen or accent, a softening feature around boulders and contrasting desert plants, or a dense mass that is especially good on slopes for erosion control. The beauty of muhlenbergias are their whispering foliage that sways in gentle breezes. They provide seeds, cover, and nesting materials for wildlife. The common species range in height from 1 ½ to 5 feet and have a variety of seed head colors, textures and patterns. They bloom from August to November.
Muhlenbergias love full sun, but tolerate part shade, are tolerant of drought, heat and cold, and can handle most soil conditions including heavy clay, alkaline or salty soils. These perennial grasses survive on rainfall alone, but look better with some supplemental summer watering. They are typically dormant in the winter and look best if trimmed to the ground every two or three years. They have no known pests or problems. A few common and most spectacular species are described below.
Oenotheras are spreading or clumping groundcovers, native to the plains, grasslands and deserts of North America. They have large, showy four-petaled flowers in pink, white, or yellow, and create carpets of bright color in desert landscapes. Oenotheras are generally night-blooming plants, but most will stay open until midday.
These widely adapted plants can be used in a variety of landscape situations from full sun to light shade. They are especially attractive when used in groupings and as a groundcover or color accent under desert trees such as palo verdes or mesquites. Evening primroses blend well with other perennial wildflowers. All types of evening primroses produce seeds that are a rich source for food for desert songbirds. The flowers attract nocturnal wildlife.
With many beautiful varieties of penstemon, it is hard to recommend just a few. These perennials are spectacular in bloom, with their trumpet shaped flowers ranging in color from orange to red, to purple, to white and everything in between. Hummingbirds can't resist their flowers.
The growth habits of penstemons include low-growing ground covers with short spikes or small basal rosettes that produce tall, long lasting floral spikes.
Penstemons generally like full sun, but require protection from reflected sun or heat here in the low desert. Most are widely adaptable to our seasonal temperature changes. They require good drainage, and are drought tolerant. During the cooler months they require almost no water, but during the dry summer months periodic irrigation is advised. Do not overwater in the summer. They readily reseed themselves to create a riot of color in your landscape. Plant 2 to 3 feet apart as penstemons resent crowding and need adequate growing room for each plant.
Prosopis, commonly known as mesquites, are extremely adaptable and tolerant to a wide range of growing conditions. They adjust to little or abundant water, and will survive during times of drought by slowing down their growth. Some specimens have a twisted character that some believe is a result of having gone through drought periods; others attribute this as a result of pruning techniques. Mesquites have supplied shade, food, and medicine for people of the desert for ages.
Mesquites have dark green leaves, rough, dark bark, and a nice sculptural growth habit. They produce yellowish cream colored catkin flowers in the spring, followed by seed pods varying in shape and size. Depending upon the variety, the canopy spreads to a mature width between 20 to 35 feet. Mesquites must be encouraged to develop extensive roots in order to maintain stability. This is done by watering along the perimeter of the canopy and not at the base of the trunk.
With over 750 species, salvia offers a great variety of forms, foliage, and seasonal colors. Sages are known for their fragrant and long-lasting, spectacular blooms. The flowers emerge above the rounded shrubs either distinctly spaced on tall skewers or in long, densely clustered spikes. Although mostly noted for their cool blue, purple or lavender blooms, some salvias produce vibrant reds, scarlet, orange, and even yellow or white blossoms. Many varieties are native to dry climates, making beautiful additions to Xeriscape gardens. Salvias create excellent natural wildlife gardens that attract hummingbirds, butterflies and bees. Some have pungent aromas that discourage browsers such as rabbits. All are non-toxic, and some are used medicinally, as herbs, or in teas.
Sennas are native to the warm regions of Australia and Africa and North America. Most sennas have fine textured foliage and bloom from late winter through spring. Most are evergreen, but those that bloom during the summer tend to be deciduous. While sennas have many uses in the landscape, they are most widely used for screening, and can reach a mature height and width of six to eight feet. They have varying degrees of cold hardiness, and require full sun. Sennas tolerate heavier soils if given infrequent, deep watering, but prefer soils that drain rapidly. Sennas are extremely drought tolerant and require little or no supplemental fertilization or irrigation once established in the landscape (after 2 – 3 years).
Their abundant color display is followed by a prolific crop of seed pods. The natural round form of sennas reduces the need for severe pruning, but lightly pruning after flowering will minimize the production of seed pods. As with most flowering plants, the butter-yellow flowers will attract pollinators including butterflies and bees. Plant your landscape carefully, keeping the ultimate size of the species in mind.
Yellow and orange bells provide a burst of summer color to desert Xeriscape gardens. Spectacular clusters of bright yellow or orange, bell shaped flowers attract hummingbirds and cover these large shrubs or small trees from April through November. Pencil-like seed pods that develop in the fall provide food for over-wintering songbirds. The bright green foliage offers a cooling effect during the hot summer months. Yellow or orange bells can be used with more evergreen desert shrubs such as hopseed bush and Arizona rosewood to form a natural screen or barrier. Tecoma can also be used against walls where it is afforded some frost protection and is a good backdrop for Baja red fairy duster, desert marigold or agave.
Ulmus parvifolia, also known as evergreen elm, lacebark elm or Chinese evergreen elm, is best characterized by its long, arching branches and rounded crown which provide dense summer shade. This tree makes a beautiful and functional addition to parks, school grounds and other open areas. Their large size and extensive root systems make them less suitable for small residential landscapes.
The evergreen elm is a fast grower, and needs plenty of room to reach its full potential. It can reach a height of 30 feet in as little as eight years. Mature growth is approximately 35 feet high and 35 feet wide, depending on watering and soil conditions.
Verbenas are heat-loving, perennial groundcovers that provide spectacular color from spring through summer. When used in mass, verbenas add splashes of color and interest to the landscape. Verbenas prefer growing in sunny locations and in well-drained soil. During their blooming period, weekly watering helps produce glorious flower displays. Irrigation can be reduced after the plants have finished blooming. Light application of nitrogen revitalizes the plants during the hot summers, but additional fertilization is not generally required. Pruning off the dried flower stalks and spent foliage in early summer will give the plants a cleaner appearance. Verbenas are short-lived, so you should anticipate replacing them after two or three years. However, some species can re-seed and naturalize in the landscape.
Yuccas are bold evergreen accent plants with a wide range of textures and exceptional white flowers. They provide interest and focal points when combined with soft-textured shrubs like ruellia and leucophyllum. Yuccas require good drainage, full sun exposure, and are hardy in cold winters. They survive on minimal watering, yet benefit from monthly soakings during the summer. They are best suited for fall and winter planting.
Yuccas provide a southwestern flavor to the landscape, but careful planning must be done when choosing their location. Because of the sharp leaves and large size of some yuccas, avoid placing close to walkways, windows or patios. Yucca’s striking silhouette makes it a good choice for background plantings. Avoid removing the old leaves of yuccas; they provide protection to the plant from sunburn, cold and insects.