Hummingbird clethra (Clethra alnifolia ‘Hummingbird’) is a compact, dwarf variety of summersweet clethra valued for its ability to attract pollinators like hummingbirds, butterflies, and bees. This popular shrub is known for its fragrant white flowers that bloom in summer, as well as its manageable size that makes it well-suited for smaller gardens. Many gardeners wonder just how big hummingbird clethra gets, as its mature size can impact how and where it is planted. In this article, we will provide key details on the expected dimensions of this dwarf clethra variety.
Typical Mature Height and Width
Hummingbird clethra is considered a dwarf or compact variety, meaning it reaches a shorter mature height and width compared to other clethra species and cultivars. On average, hummingbird clethra grows to be about 3-5 feet tall at maturity. It spreads to a width of 3-4 feet wide when it is fully grown. This makes it a petite shrub that is easy to incorporate into perennial beds, mixed borders, containers, and other garden spaces where a small plant is desired.
Here are some quick facts on the mature size of hummingbird clethra:
– Typical height range of 3-5 feet tall
– Average mature width of 3-4 feet wide
– Classified as a dwarf or compact clethra variety
– Much smaller than regular summersweet clethra, which can reach 6-8 feet tall and wide
Its dense, mounded form and modest size make it suitable for gardeners without a lot of available space. It also works well in garden designs where shorter, smaller-statured plants are needed.
Growth Rate
In addition to its compact mature size, hummingbird clethra is also known for being relatively slow growing. It reaches its full size over a period of 5-10 years. The plant only grows about 12-18 inches per year on average. This gradual growth habit makes it easy to maintain in the garden.
Here’s an overview of the typical growth rate of this clethra cultivar:
– Slow growing, only about 1-1.5 feet of growth per year
– Usually takes 5-10 years to reach full mature size
– Does not require frequent pruning to control size
– Gradual growth allows it to be planted in the garden for many years
The slow growth of hummingbird clethra means gardeners do not have to worry about it outgrowing its space too quickly. It will take several years to mature, allowing you to enjoy it as a small shrub for a long time before it eventually reaches its maximum size. This gives you plenty of time to decide if you need to relocate it to a different spot.
Height and Width Range
While the average mature size of hummingbird clethra is 3-5 feet tall and wide, this compact shrub can occasionally reach slightly larger or smaller dimensions. The actual size depends on growing conditions and care.
Here is an overview of the potential height and width range:
Height
– Minimum height around 2 feet
– Maximum height of up to 6 feet
– Typically tops out at 3-5 feet
Width
– Minimum width of approximately 2 feet
– Maximum spread of up to 5 feet
– Usually matures at 3-4 feet wide
So in ideal conditions, this clethra may occasionally grow up to 6 feet tall and 5 feet wide. However, it more commonly stays in the 3-4 feet tall and wide range at maturity.
Monitoring its environment, pruning, and providing proper care can help keep hummingbird clethra closer to its typical compact size. But some variation in final dimensions is to be expected.
Size Factors
Several factors play a role in determining the ultimate height and width of hummingbird clethra. The following growing conditions and plant care practices can affect its dimensions:
Location and Soil
– Does best in organically rich, acidic, moist soil
– Thrives in full sun to part shade
– Warm zones encourage larger size
Pruning
– Can be pruned in late winter to shape and restrict size
– Pruning right after flowering avoids removing next year’s flower buds
Fertilization
– Avoid over-fertilization, which can promote leggy growth
– Moderate fertilization supports compact growth habit
Irrigation
– Prefers consistent moisture
– Drought stress can inhibit growth
By optimizing these inputs, you can typically keep your hummingbird clethra closer to the compact 3-5 feet size range. Allowing it to dry out or become nutrient deficient can limit its size. But also avoid pushing growth too much through over-watering or over-fertilizing.
Size Over Time
Tracking the size of hummingbird clethra over time can help provide clues on its growth habit and how quickly it is reaching maturity in your specific garden conditions. Here is an overview of its typical size progression:
First Year
– Grows around 1-1.5 feet as a new plant
– Forms a compact mound about 1-2 feet wide
Second Year
– Reaches 1.5-2.5 feet tall
– Spreads to 2-3 feet wide
Third Year
– Achieves 2-3.5 feet in height
– Approaches mature width of 3-4 feet
Fourth Year
– Grows to 2.5-4 feet tall
– Fills out to desired mature form and density
Fifth Year and Beyond
– Gradually achieves mature height of 3-5 feet tall
– Maintains mature width of 3-4 feet wide
– May take up to 10 years to top out at maximum size
This steady, moderate growth allows plenty of time to decide if the shrub needs to be moved, pruned, or trimmed to keep its dimensions in check within your garden space. Monitoring its size over time can help you stay ahead of any necessary care.
Size in Container Gardens
In addition to using hummingbird clethra in in-ground plantings, it also makes an excellent addition to container gardens and planters. When grown in pots, its size stays on the smaller end of its growth potential. You can expect the following dimensions when keeping it in containers:
Height
– Typically tops out at 2-4 feet tall
– Can be maintained at 1-3 feet with pruning
Width
– Usually stays within 2-3 feet wide
– Pruning can restrict spread to 1-2 feet
Container Size
– Minimum of 12-16 inches wide suggested
– Larger is better to prevent root restriction
The limited space and root room in containers, along with routine fertilization and ample watering, will promote a controlled, compact growth habit. Pruning and training into shapes can further limit the size. Switching to a larger container every few years can support steady growth.
Design Uses for Small Size
One of the big advantages of hummingbird clethra’s petite size is its versatility in garden design. The compact shrub is suitable for use in the following locations:
– Small residential gardens
– Urban yards and courtyards
– Borders and beds
– Foundations
– Rock gardens
– Containers
– Front walkway or entryway plantings
– Low hedges and screens
– Mixed shrub groupings and perennial beds
Its ability to thrive in partial shade also allows it to be tucked into planting areas that do not receive full sun. The shrub’s modest dimensions and slow growth make it very low maintenance compared to larger clethra varieties.
Pairing with Companion Plants
In addition to being used alone, hummingbird clethra can be combined with other plants for added interest and contrast. Some ideal options for plant pairings include:
Perennials
– Catmint
– Lavender
– Salvia
– Yarrow
– Ornamental grasses
Annuals
– Impatiens
– Begonias
– Coleus
– Lantana
Small Shrubs
– Dwarf spirea
– Compact hydrangea
– Dwarf butterfly bush
– Low-growing azaleas
– Dwarf rhododendrons
Choose companion plants with similar cultural requirements and soil needs. Repeat colors and textures found in the clethra flowers and foliage for a cohesive design.
Maintenance to Control Size
While hummingbird clethra is relatively low maintenance, some minor care is required to keep it at its best size. Here are a few tips:
– Prune annually or as needed to shape and restrict size
– Provide moderate water and fertilizer to avoid leggy growth
– Allow soil to dry slightly between waterings
– Watch for pests like scale and spider mites that can affect health
– Remove crossed or overcrowded stems to encourage air flow
– Transplant into a larger container if rootbound
With proper siting, planting, and care you can easily keep your hummingbird clethra looking fabulous and close to its compact dimensions for many years. Enjoy its graceful form, fragrant blooms, and ability to attract pollinators while occupying minimal garden space.
Conclusion
Hummingbird clethra is valued by gardeners for its petite, compact size that works perfectly in today’s smaller gardens. While its average mature height is 3-5 feet tall and wide, it can occasionally reach up to 6 feet tall and 5 feet wide at its maximum size. But you can easily keep it much closer to its dwarf stature by providing ideal growing conditions and pruning as needed. The slow growth rate allows plenty of time to adjust care to achieve the perfect compact form. With proper maintenance, this beautifully fragrant, pollinator-friendly shrub will enhance your landscape without overtaking it for years to come.
