While desert plants are unusually well-adapted to life without shade, desert gardeners certainly appreciate a shade tree or two providing much-needed coolness to their outdoor escapes. Many desert trees put on a glorious show of purple blooms in the spring, drawing admiring glances from passers-by and visits from grateful nectar-eating hummingbirds and butterflies.
California redbud (Cercis orbiculata) is commonly seen in Grand Canyon Park, where its reddish-purple blooms complement the Canyon's sunset colors. Flowers cover the branches in early spring before the trees leaf. The redbud, an effective erosion control tool, can survive desert flash floods.
The tree's nectar feeds honeybees. Wild goats and deer forage on its leaves and seedpods. Its green leaves turn brilliant red or yellow in the fall, adding more garden interest. California redbud loves full sun and tolerates drought. It does well in a wide range of soils, including the nutritionally-deprived but well-drained of its native habitats.
Redbuds grow from seed pods collected in the fall. Pour boiling water on the seeds for overnight soaking to soften their protective outer layer. Plant them immediately 1 to 2 inches apart in flats and cover them with one-quarter inch of planting mix fortified with slow-release fertilizer. Keep them outdoors in a partly shaded area away from the wind. Water them during the winter and plant them in their permanent sunny well-drained locations when they are 1 foot tall.
Desert willow (Chilopsis linearis) is appealing as much for its twisted growth habit as it is for its striking summer blooms. Reaching from 15 to 40 feet tall, desert willow produces trumpet-like 1 to 2-inch purple flowers, often with striking yellow or white streaked throats. Flowers peak in May and June, but will bloom sporadically after summer rain. They, give way to narrow dangling seedpods in the fall.
Highly drought-resistant, desert willow is a popular ornamental tree. It grows quickly, says the Lady Bird Johnson Wildflower Center, with just enough watering to maintain its leaves and stimulate summer bloom The flowers draw hummingbirds and butterflies, and the seeds are a cold weather food source for birds.
Desert willow grows easily from freshly collected seeds. Started plants are available at nurseries. The trees like full sun and well-drained soil, rich in limestone and low in organic matter if possible. Remove dead flowers and seedpods and let the trees dry out between watering to encourage continued bloom.
Desert ironwood, or tesota tree (olneya tesota) reaches up to 30 feet in height. An evergreen desert ironwood has spines. Its densely rounded crown often exceeds its height, making it a good shade provider in places where taller trees aren't ideal. Its pinkish-purple flower spikes bloom in April and May, prior to the appearance of new leaves.
The tree's exceptionally hard and heavy wood makes durable boxes and bowls. It polishes well but takes a toll on wood cutting tools. Ironwoods beans are edible. Ironwood likes like full sun and dry sandy soil. Plant the fresh seed immediately or soak stored seed overnight to soften their coating. Trees are also available in nurseries.