Esperanza and yellow bells are two common names for Tecoma stans, a species of small tree prized for its golden yellow flower clusters. Two subspecies are widely cultivated in landscaping: Arizona yellow bells (Tecoma stans var. angustata) and common yellow bells (Tecoma stans var. stans). Both have similar physical characteristics, but they vary slightly in their climate requirements, growing conditions and overall care.
As a group, yellow bells grow best throughout U.S. Department of Agriculture plant hardiness zones 7 to 11, although cold tolerance varies between species. Common yellow bells originated in subtropical and tropical landscapes from Texas to Argentina and are less cold tolerant. They perform best within USDA zones 10a to 11, although they will survive outdoors in USDA zone 9 with protection. Arizona yellow bells tolerate colder conditions and will thrive in USDA zones 7 to 11, although they may die back to the ground in USDA zone 7 without protection.
Yellow bells require full sun exposure, regardless of the species. Shade reduces flowering and encourages a rangy, undesirable shape, which increases the need for pruning. Grow yellow bells in a bed with southern exposure and moderately fertile, fast-draining soil. In colder areas where frosts are common, grow yellow bells in a large, draining pot with a diameter of at least 12 inches. Use a growing mix of 3 parts standard potting soil with 1 part washed, medium-grit sand to increase drainage and porosity in the soil. Bring potted yellow bells indoors and place them in a warm, south-facing room if frost is forecasted.
The watering needs of yellow bells vary according to the season and the plant's growing conditions. Established yellow bells tolerate moderate drought but will lose leaves if kept too dry during the spring. Provide 1 inch of water weekly from late winter until late spring, wetting the soil in the top 6 to 15 inches, to encourage yellow bells to maintain their foliage. Water deeply but infrequently during the summer months, allowing the soil to dry out completely between waterings. Potted yellow bells need regular watering from spring until late summer. Water when the soil dries out on the surface, then water until the excess trickles from the pot. In winter, water potted yellow bells only enough to keep it from wilting.
Yellow bells are light feeders that require very little supplemental fertilizer. However, potted yellow bells or those grown in very poor, porous soil may need a little boost of nutrients during the summer months to support their growth. Dissolve 1/2 teaspoon of 10-10-10 or 7-9-5 fertilizer in 1 gallon of water. Apply the solution to the moist soil bi-monthly -- or every eight weeks -- from spring until later summer. Feed potted yellow bells monthly, especially if it grows very slowly or its flower production is lacking. Cease feeding in late summer at least eight weeks before the first frost so the new growth has a chance to mature, then resume feeding in spring after temperatures warm and new growth emerges.
Adaptable and showy, common yellow bells may seem like an ideal addition to landscaping in warmer climates, but they are not without drawbacks. They are prone to invasiveness in areas such as Florida and Hawaii, where they can crowd out native plants. Grow common yellow bells in pots in warm, frost-free climates such as Florida or Hawaii where they might escape cultivation and become invasive, or grow them in garden beds surrounded by concrete or other impermeable surfaces. Prune off the flowers after they fade to prevent seed production and compost clippings to keep them from taking root.
- Arizona State University Virtual Library of Phoenix Landscape Plants: Tecoma Stans
- Floridata: Tecoma Stans
- Missouri Botanical Garden: Tecoma Stans
- Duke's Handbook of Medicinal Plants of Latin America; James A. Duke
- Logee's Plants for Home and Garden: Gelsemium
- Lady Bird Johnson Wildflower Center: Tecoma Stans
- University of Florida IFAS Extension: Tecoma Stans var. Stans
Samantha McMullen began writing professionally in 2001. Her nearly 20 years of experience in horticulture informs her work, which has appeared in publications such as Mother Earth News.