Yellow bells is an eye-catching desert shrub that looks like it belongs in the tropics, but is a southwest desert native. Here’s everything you need to know about planting and caring for this popular landscape plant.
Large clusters of brilliant yellow flowers and bright green leaves make yellow bells (Tecoma stans) a standout landscape shrub. When in bloom, it’s truly a show-stopper that attracts the attention of humans, as well as hummingbirds, bees, and butterflies.
And this native shrub is as tough as it is beautiful. It thrives in full sun and almost any soil, and needs little water once established.
They are so tough, it’s not uncommon to see them thriving in parking lots and other inhospitable places, looking fresh and cheerful despite neglect.
Why I Like This Plant
- Cheerful yellow flowers & bright green leaves
- Loves full sun and even reflected heat
- Low maintenance
- Attracts pollinators
- No thorns, not toxic
Things to Watch Out For
- Yellow bells need pruning to remove damaged branches and to rejuvenate.
- They are prone to caterpillar damage.
- They produce a moderate amount of litter.
- The seeds attract small mammals, a concern if you have rodent issues.
Optimal Growing Conditions
If you’re thinking of adding a yellow bells to your garden, you need to find a suitable place that will keep it healthy and looking good… while minimizing maintenance for you.
Here are the key factors to keep in mind.
Temperature
Yellow bells should ideally be grown in USDA Hardiness Zones 9 – 11 (but I’ve seen a few sources that push that lower range to 8 or even 7).
It’s semi-deciduous but cold hardy. It suffers leaf damage in the upper 20s and dies back in the mid 20s. But it rebounds in the spring, even when the temperatures dip to the low teens.
Sun Exposure
Yellow bells need full sun to perform their best and don’t mind the reflected heat of a garden wall. They get lanky and produce fewer flowers when grown in part shade.
Size and Growth Rate
It’s a fast grower that typically reaches a mature size of 10 feet tall by 6 feet wide. Its maximum size is generally determined by winter temperatures. In places where it doesn’t die back in the winter, it grows much larger, up to 20 feet tall.
Soil
Yellow bells are not particular about soil. They grow well in any soil, from sandy to clay, provided it’s well-draining.
Pests and Diseases
Yellow bells are susceptible to damage from moths known as leaf-tiers or leafrollers (Antigastra catalaunalis). The caterpillars leave webs and poop, and skeletonize the leaves. An infestation looks like this:
If you have an otherwise healthy plant, the caterpillar damage won’t hurt your plant, it’s purely cosmetic. So if the damage is minimal, consider co-existing with the caterpillars. They turn into moths that are important pollinators and a food source for other wildlife.
But if the damage is extensive or becomes an unacceptable eyesore, prune off the worst areas or use the jet spray on your hose to dislodge them. Spraying insecticides, soap, or Bt (Bacillus thuringiensis) is largely ineffective since caterpillars are tightly wrapped in leaves and protective webbing.
Leaf-tier caterpillars are a relatively new yellow bells pest.
They were first noticed in Tucson and Phoenix in 2012.
Yellow Bells:
The Essentials
| Common Name | Yellow bells |
| Scientific Name | Tecoma stans |
| Origin | Sonoran, Chihuahuan Deserts |
| Plant Type | Semi-deciduous shrub |
| USDA Zones | Zones 9 – 11 |
| Cold Hardiness | To 10℉ |
| Flower Color | Yellow |
| Flower Season | Spring, summer, fall |
| Mature Size | 10’ high x 6’ wide |
| Growth Rate | Moderate to fast |
| Sun Tolerance | Full sun |
| Water Needs | Low to moderate |
| Pests & Diseases | Caterpillar damage |
| Garden Friendly | No thorns, non-toxic |
| Wildlife | Attracts pollinators |
How to Plant
The rule of thumb when planting any shrub or tree in the desert is to dig a hole three times as wide as the root ball but no deeper. Amending the soil is not recommended. Counterintuitively, backfilling with the same native soil you just dug up helps your plant develop a stronger root system.
When to Plant
The best time to plant yellow bells is in the fall. This gives your shrub three seasons to grow roots and get established before the following summer.
The second best time is in spring, the earlier the better. This still gives your plant time to get established before the intense heat of June arrives.
How to Care for Yellow Bells
Whether you’ve recently planted a yellow bells shrub or have an existing plant in your yard, here’s how to take care of it to keep it healthy and looking its best.
How to Water New Plants
Once you’ve got your yellow bells in the ground, watering is your most immediate concern. Here is the recommended watering schedule for new shrubs planted in the spring or fall.
| Weeks 1 & 2 | Every 3 – 4 days |
| Weeks 3 & 4 | Every 5 – 7 days |
| Weeks 5 & 6 | Every 7 – 10 days |
| Weeks 7 & 8 | Every 10 – 14 days |
After week 8, gradually extend the time between waterings.
How to Water Established Plants
As your plant gets established, there are two watering factors to consider.
- First is how often to water. This will vary with the seasons.
- Second is how much water to give your shrub with each watering. This depends on the current size of your plant.
To determine the ideal watering schedule for yellow bells or any desert shrub you’ll find everything you need to know, including easy-to-use charts, at How to Water Desert Shrubs: How Often? How Much?
Should You Fertilize?
While fertilizing is not necessary, Arizona State University suggests fertilizing during the summer to encourage flowering.
How to Prune
If you live where the temperature drops below freezing, expect your yellow bells to incur cold damage. When this happens, remove any damaged branches in the spring after the danger of frost has passed.
While yellow bells is a vigorous grower, it’s also manageable. You can keep its size in check by cutting it back by half in the spring and trimming it lightly in late summer, if needed.
Yellow bells is one of the many desert landscape shrubs that benefits from hard pruning, i.e., cutting it back to one foot in early spring every 5 years or so.
Prune away leafroller damage anytime you notice it, usually in the spring or mid to late summer.
Yellow Bells Cultivars and Varieties
Yellow bells has many beautiful hybrids that differ in flower color, size, and/or cold-hardiness. Here are some of the favorites you might come across and their main points of difference from the parent plant:
- Tecoma x ‘Gold Star’ — compact, more abundant blooms
- Tecoma x ‘Bells of Fire’ — compact, red flowers
- Tecoma x ‘Sparky’ – yellow and red flowers
- Tecoma x ‘Solar Flare’ — tangerine flowers
- Tecoma x ‘Orange Jubilee’ — orange flowers, cold hardy to 0℉
- Tecoma x ‘Sierra Apricot’ — compact, apricot flowers
- Tecoma x ‘Sunrise’ — yellow and orange flowers
Arizona Yellow Bells
There is a naturally-occurring variety of yellow bells called Arizona yellow bells (Tecoma stans var. angustata). It is native to the southwestern US and adjacent Mexico. Unlike typical yellow bells, it has narrow, ribbon-like leaves and slightly smaller flowers. It is also more tolerant of drought and cold, and is more attractive to native pollinators.
This variety is not as readily available as the typical yellow bells, but can be found at nurseries that carry native plants.
Plant Lover Facts
Yellow bells (Tecoma stans) has numerous common names including yellow trumpet bush, trumpet-flower, yellow bignonia, yellow elder, and esperanza, which means “hope.” It also goes by the scientific name Stenolobium stans.
Yellow bells have a huge natural range. They’re native to the desert southwest, but also grow throughout Central and South America. They’ve naturalized throughout the world and in wetter, warmer climates can become invasive.
Unexpectedly, to those of us who know yellow bells as a popular desert landscape shrub, Kew Botanic Gardens database describes this plant as a “tree that grows mainly in the wet tropical biome.”
Cobras are among the most deadly snakes in the world. When researchers tested medicinal plants that have been used traditionally to treat cobra bites, an extract of yellow bells came out on top and, surprisingly, was even more effective than antiserum.
Have you grown this plant?
Was it a “hit” or a “miss” in your garden?
Please share your experience in the comments below!
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.
Photo Credits
Alejandro Bayer Tamayo, CC BY-SA 2.0, Wikimedia Commons
Arizona State University’s Virtual Library of Phoenix Landscape Plants
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