Hummingbird trees, also known as ocotillo or Fouquieria splendens, are a unique desert plant found primarily in the southwestern United States and northern Mexico. They thrive in hot, arid climates and are well-adapted to survive in zones 8B to 11. Here we will explore the ideal growing zones for hummingbird trees and the conditions they need to flourish.
Zones 8B to 9B
Hummingbird trees can survive winter temperatures as low as 15 to 20°F, though they may die back to the ground in harsh winters. This cold hardiness makes zones 8B and 9B suitable for growing hummingbird trees. These warmer zones are found across the southernmost parts of the United States, including southern California, Arizona, New Mexico, Texas, Louisiana, Mississippi, Alabama, Georgia and Florida.
In zones 8B and 9B, hummingbird trees may lose some or all of their leaves in winter when temperatures drop below freezing. However, the roots are hardy and will resprout leaves as soon as warmer weather returns in spring. Supplemental water during winter dormancy is beneficial. While hummingbird trees can handle zones 8B to 9B, they will thrive with the warmer winters of zone 9 and higher.
Ideal growing conditions
Here are the ideal growing conditions for hummingbird trees in zones 8B to 9B:
- Full sun exposure
- Well-drained, sandy or gravelly soil
- Minimal watering once established
- Temperatures between 15-20°F in winter
- Hot summers with temperatures above 100°F
- Low humidity
- Minimal fertilizer requirements
Zones 10A to 11
Zones 10A through 11 provide the ideal climate for growing vibrant, healthy hummingbird trees. These hot, arid zones occur across the desert Southwest including southern California, southern Nevada, Arizona, southern Utah, New Mexico and west Texas.
In zones 10A to 11, hummingbird trees will thrive with no need to worry about cold damage. Typical winter lows stay safely above 30°F. The hot, dry summers help trigger the spectacular floral displays that give hummingbird trees their name. This is the climate they are native to and evolved for.
Ideal growing conditions
Here are the perfect growing conditions for hummingbird trees in zones 10A to 11:
- Full blazing sun
- Fast draining, sandy or rocky soil
- Minimal water once established; avoid overwatering
- Long, hot summers with temperatures exceeding 100°F
- Warm winters, with lows above 30°F
- Low humidity
- Occasional supplemental fertilizer
How Cold Temperatures Affect Hummingbird Trees
One of the defining features of hummingbird trees is their stark winter appearance. When temperatures drop in winter, hummingbird trees shed their leaves and go dormant. This helps them preserve moisture and energy when water is scarce. It also minimizes damage from freezing temperatures.
In zones 8B to 9B, the winter leaf drop may be partial or complete depending on how cold it gets. Hummingbird trees can handle brief temperatures as low as 15°F when dormant. But protracted freezing weather below 20°F may kill back more of the stems.
Despite their leafless look, hummingbird trees are still alive and well in winter. Early spring growth begins when temperatures rise and days lengthen. Damaged stems from harsh winters may take longer to revive.
Protecting Hummingbird Trees from Cold Damage
Here are some tips to help hummingbird trees survive colder winters:
- Provide supplemental water during winter dormancy every 4-6 weeks if rainfall is scarce. This encourages root growth.
- Mulch around the base with bark chips or gravel to insulate roots from hard freezes.
- Delay pruning until after the last frost. Pruning encourages tender new growth susceptible to frost damage.
- Wrap or cover plants with fabric if an extreme freeze is forecasted.
- Select sheltered planting sites protected from harsh wind.
Ideal Sun Exposure
Hummingbird trees need full sun to thrive. Native to the sunny deserts of the Southwest, they rely on high light conditions. In their natural habitat, hummingbird trees grow in open exposures with no shade or tree cover.
When planted in ideal zones 8B to 11, situate hummingbird trees where they will receive full sun for most or all of the day. At least 8 hours of direct sun is best. Morning sun is particularly important.
Insufficient sunlight will result in reduced flowering and fewer of the vibrant red blooms that give hummingbird trees their name. Shaded plants may also become lanky and sparse in form as they reach for sunlight.
Encouraging Flowering
Here are some tips to encourage prolific flowering:
- Choose south facing planting sites with no obstructions to sunlight.
- Space multiple plants at least 10 feet apart to prevent mutual shading.
- Prune back encroaching trees or shrubs that may cause shade.
- Reflect sunlight onto plants with white-painted walls or light colored gravel mulch.
- Rotate potted plants to ensure even sun exposure.
Soil Needs
Hummingbird trees thrive in fast-draining desert soils. Sandy, gravelly soils are ideal as they prevent rot and allow rapid permeability. Clay soils or wet boggy areas will lead to root rot and death of the plant.
When planting hummingbird trees, choose a site with loose, porous soils. If needed, amend heavy soils with sand, gravel or decomposed granite to improve drainage. Mix in a small amount of compost at planting time to provide nutrients. But avoid rich, heavy composts that retain moisture.
Raised beds also provide excellent drainage for hummingbird trees. Use fast-draining fill material like sand, gravel or decomposed granite. A gravel mulch helps reduce evaporation and keeps soil from compacting.
Preventing Root Rot
Here are some tips for preventing root rot in hummingbird trees:
- Select planting sites with fast drainage – slope away from foundations.
- Amend clay or compacted soils.
- Allow soil to dry between waterings; avoid frequent shallow watering.
- Apply 4-6″ layer of gravel as mulch to improve drainage.
- Plant in raised beds filled with porous materials.
- Treat diseased plants with fungicide promptly.
Water Needs
Hummingbird trees are extremely drought tolerant and require minimal irrigation once established. Too much water is more detrimental than too little for these desert natives.
During the first two years after planting, provide supplemental water every 2-4 weeks during dry periods. Soak the entire root zone and allow the soil to dry completely before watering again. Established plants need infrequent but deep soaking.
Rely on rainfall as much as possible. In zones 8B to 11, hummingbird trees will receive enough precipitation to meet their needs if properly mulched. Avoid frequent shallow watering which leads to root rot.
Signs of Underwatering
Here are some signs hummingbird trees need more water:
- Leaves wilting or dropping
- Branch dieback
- Lackluster or reduced flowering
- Stunted growth
- Soil remains dry 2-3 inches below surface
Signs of Overwatering
Here are some signs of overwatering:
- Mushy, discolored roots
- Yellow, wilt-like foliage
- Sudden leaf drop
- Low foliage despite adequate sunlight
- Fungus on stems or soil
- Standing water around base
Fertilizer Needs
Hummingbird trees have modest fertilizer requirements when grown in their ideal zones. Desert soils tend to be low in nutrients, so occasional supplemental feeding encourages flowering and growth.
At planting time, mix a slow-release general purpose fertilizer into the soil per label rates. This will provide nutrients for the first season of growth. After establishment, fertilize hummingbird trees once yearly in early spring.
Use a low nitrogen, phosphorus-rich fertilizer designed for desert plants. Granular fertilizers can be scattered beneath the plant and scratched into the soil surface. Liquid fertilizers should be applied at half strength.
Signs Hummingbird Trees Need Fertilizer
Here are some indications hummingbird trees need more nutrients:
- Reduced flowering and smaller blooms
- Yellowing foliage
- Lackluster growth
- Noticeably small leaves and stems
- Failure to resume growth in spring
Hardiness Zone Map for Hummingbird Trees
This map shows the USDA hardiness zones suitable for growing hummingbird trees in green. Hummingbird trees can survive winter lows down to zone 8B but thrive in zones 9-11.
| Zone | Temperature Range | Recommended for Hummingbird Trees? |
|---|---|---|
| 8A | 10 to 15°F | Not recommended, may suffer cold damage |
| 8B | 15 to 20°F | Can survive but not ideal, may die back |
| 9A | 20 to 25°F | Suitable, may defoliate in harsh winters |
| 9B | 25 to 30°F | Suitable, avoid severe prolonged freezes |
| 10A | 30 to 35°F | Ideal, avoids winter dieback |
| 10B to 11 | 35°F and up | Perfect, no risk of cold damage |
Choosing the Best Varieties
There are several varieties of hummingbird tree to choose from. Here are some top options for zones 8B to 11:
Pink Ribbons
- Vibrant pinkish-red flowers
- Height 15-25 feet
- Narrow upright form
- Prolific bloomer
- Cold hardy selection
Sierra Bouquet
- Bright red flower clusters
- Height 10-15 feet
- Low spreading form
- Thrives in reflected heat
- Tolerates alkaline, clay soil
Ruby Glow
- Fiery orange-red blooms
- Height 12-18 feet
- Fast growing
- Withstands drought
- Great for coastal areas
Caring for Hummingbird Trees
Here is a summary of key care guidelines to help hummingbird trees thrive:
Sun and Soil
- Full sun
- Well-drained soil
- Avoid clay, standing water
- Amend poor soils
- Use gravel mulch
Water
- Drought tolerant when established
- Infrequent deep soakings
- Allow soil to dry before re-watering
- Avoid frequent shallow watering
Fertilizer
- Low annual feeding in spring
- Use phosphorus-rich fertilizer
- Scatter around drip line
Pruning
- Prune as needed for shape/size
- Thin dense growth to encourage flowering
- Prune lightly in summer after flowering
- Avoid heavy pruning in fall
Pest/Disease Control
- Generally trouble free
- Ensure good drainage
- Treat stem fungus promptly
- Control scale if present
Conclusion
Hummingbird trees thrive in the hot, arid climates of zones 8B through 11. Native to the desert Southwest, they need full sun exposure, well-drained soils and minimal irrigation. Ideal zones provide protection from severe winter freezes that may damage stems and inhibit flowering. Given their basic requirements for sun, porous soil and little water, hummingbird trees are an excellent choice for xeriscapes and water-wise gardens in warmer regions.
