Scientific: Tecoma stans
Common: yellow bells, esperanza, yellow elder
Family: Bignoniaceae
Origin: Broadly distributed from South Florida, and the extreme desert Southwest south through Mexico all the way south to into Argentina.

Pronounciation: Ta-CO-ma STANS

Hardiness zones
Sunset
12-13, 16, 18-24
USDA 9 (sometimes cold injury in exposed areas, but quick recovery)

Landscape Use: Floral accent, background screen, specimen around large patios and ramadas exemplifying regional or Spanish architecture; best used in oasis and transition landscape designs settings.

Form & Character: Evergreen to partial evergreen large shrub, upright and open, festive, informal, subtropical to tropical.

Growth Habit: Vigorous and upright to 15 to 20 feet but can be easily maintained at 5 to 10 feet. Hardened stems of all Tecoma species are very brittle. Semi dwarf cultivars are generally less vigorous and are more serviceable in the landscape as accent shrubs..

Foliage/texture: Opposite, pinnately compound leaves on brownish gray stems, leaflets coarsely serrate, stem lenticels and auxiliary dormant buds are obvious; medium coarse texture.

Flowers & fruits: Beautiful yellow to yellow orange red trumpet flowers in terminal clusters; fruits are long, narrow, unattractive brown pods.

Seasonal color: Yellow to apricot to red colored flowers during all growing season, heaviest in spring and fall.

Temperature: Heat loving, but freeze sensitive. In climates colder than Phoenix, yellow bells will freeze to the ground every winter. In Phoenix, yellow bells will have freeze damage to leaves and small terminal stems most winters, but recovers very quickly in the spring.

Light: Full sun is required, will grows in an loose, open and rangy manner if shaded even lightly.

Soil: Yellow bells is tolerant of all Arizona soils except those with the highest degree of alkalinity.

Watering: Yellow bells responds well to regular water and fertilizer applications during summer by producing more vigorous growth and heightened flowering. It will tolerate only moderate amounts of drought.

Pruning: Prune yellow bells hard in the winter to control height and stiffen upright character.

Propagation: Softwood cutting, seed.

Disease and pests: In the Phoenix area, Texas and phytophthora root rot fungi occasionally cause sudden plant death, usually only in heavy soils with a former agricultural use history. During late summer of good monsoon years, a leaf skeletonizer catepillar will ravage foliage on upper stems primarily. The damage to foliage is short lived and cosmetic, not lethal. Several chemical control strategies are available including a biological spray Bacillus thurengensis; however, given the growth habit of Tecoma and its rapid recovery after pruning, I recommend that one strongly head back (prune) infested plants and dispose of the damaged material.

Additional comments: This is a great, medium to large (depending on cultivar) accent shrub for large spaces. Yellow bells can look 'sparse' during periods of winter cold or high summer heat. T. stans var. angustata (Arizona yellow bells) is a smaller and more fine textured, northern varietal cline from southern Arizona, New Mexico, west Texas and northern Mexicio that is more drought tolerant, but also more susceptible to Texas root rot in most formerly agricultural soils. Other superior cultivars of T. stans in the Phoenix area include 'Gold Star' and 'Sundance', both of which are of smaller size and flower profusely. The cultivar 'Gold Star' was selected by Texas plant breeder Greg Grant from a private garden in San Antonio, Texas. 'Sunrise' is a cultivar that has yellow blooms veined with copper threads. 'Crimson Flare' is a cool cultivar with deep red flowers. 'Sierra Apricot' is a unique dwarf hybrid cultivar with abundant apricot-colored flowers that grows to about 3 to 4 feet in height with a slightly greater spread. It is a heat tolerant hybrid of T. stans and T. alata

Yellow bells has long been known and used by native Americans of the Southwest and Mexico for bowmaking, bee fodder and medicines. It is considered an invasive plant in Hawaii.