A North American native, summersweet marks the ending of summer with its fragrant white flowers. This small to medium shrub starts blooming in August and continues the show into fall when its foliage turns yellow. Hummingbirds and butterflies flock to summersweet blossoms, but deer steer clear, making this a great shrub for locations with a large deer population.
Summersweet Overview
| Genus Name | Clethra alnifolia |
| Common Name | Summersweet |
| Additional Common Names | Sweet pepperbush |
| Plant Type | Shrub |
| Light | Part Sun, Sun |
| Height | 2 to 8 feet |
| Width | 2 to 6 feet |
| Flower Color | Pink, White |
| Season Features | Colorful Fall Foliage, Fall Bloom, Summer Bloom |
| Special Features | Attracts Birds, Fragrance, Low Maintenance |
| Zones | 3, 4, 5, 6, 7, 8, 9 |
| Propagation | Stem Cuttings |
| Problem Solvers | Good For Privacy |
Where to Plant Summersweet
Summersweet does best in full sun and soil that is evenly moist soil—a combination that can be challenging. If you need to plant the shrub in partial shade to fulfill its moisture requirements, that is acceptable too, as long as you avoid hot, dry locations. In terms of soil pH, slightly acidic to neutral is best.
For perennial planting beds, there are compact varieties that add year-round structure and late-summer interest. You can also take advantage of the shrub’s prolific suckering and use it as a hedge along a property line, creating a wildlife oasis at the same time.
How and When to Plant Summersweet
Plant summersweet in the spring. Dig a hole at least twice the size of the root ball and just as deep. Place the shrub in the hole and gently spread out the roots. Backfill with the original soil so that the top of the root ball is flush with the soil. Tamp down the soil and water it well. Keep the soil moist and water it regularly during the first growing season to encourage a strong root system.
Space plants 4 to 6 feet apart, depending on the intended landscape use. To grow it as a specimen, give it more space. For a hedge, plant the shrubs closer together.
Summersweet Care Tips
Like most native plants, summersweet only requires minimal care.
Light
Plant summersweet in full sun or part shade. It will grow in full shade but tends to have a less attractive, open and loose habit.
Soil and Water
Ideally, the soil mimics swampy woodlands, the native habitat of summersweet, but the shrub can also grow in average soil with a pH between 5.5 and 7.5.
Water the shrub regularly during the first growing season to establish a deep, extensive root system. Mature shrubs should be watered deeply in periods of drought. To prevent soil moisture evaporation, blanket the soil around the shrub with a 2-inch-thick layer of mulch.
Temperature and Humidity
Summersweet is adapted to a wide range of climates, from areas with subzero winters to places with hot summers. It does not have any humidity requirements or issues with high humidity.
Fertilizer
A one-time fertilization with a slow-release shrub and tree fertilizer in the early spring is enough, as summersweet is a light feeder. For the amount to use, consult product label instructions.
Pruning
Other than removing damaged or dead branches, pruning of summersweet it optional and the shrub responds well to pruning. It blooms on new wood so you can prune it in the late winter or early spring without worrying about accidentally removing flower buds. The best time to prune is after it has started to leaf out.
Potting and Repotting Summersweet
If you want to grow summersweet in a pot, select a dwarf variety such as Sugartina (‘Crystaltina’). Use a container that has large drainage holes and is big enough to accommodate two to three years of growth, about 8 inches wider than the root ball. Fill the container with well-draining potting mix. Like all potted plants, it will need frequent watering, up to daily in hot summer weather.
Although summersweet is very winter-hardy, container-growing exposes the roots to the cold, which can cause dieback. If you live in a region with subzero winters. you need to winterize the pots, either by sinking the container in the ground, placing it in a second, larger pot to create a planting silo, or wrapping the pot in several layers of burlap or bubble wrap.
Pests and Problems
This shrub has no serious insect or disease problems. In dry conditions, it might attract spider mites. In wet fall weather, it might get infected with leaf spot but since this occurs late in the season and the shrub will drop its leaves shortly thereafter, it does not warrant treatment. Just make sure to rake and collect all diseased leaves.
How to Propagate Summersweet
Summersweet can be propagated from softwood cuttings or seed. Propagation from cuttings is preferable not only because it is faster but also because it will produce a new plant that is true to the parent. When propagating summersweet, make sure that the variety is not protected by a plant patent.
In the early summer take a 3- to 4-inch stem cutting of new, soft growth. Dip the cut end in rooting hormone and insert the cutting 1 to 2 inches deep into pots filled with damp potting mix. Cover the container with a plastic dome (an inverted soda bottle with the top part removed works well) because the cutting needs relative high humidity to root. Keep the cutting moist at all times. The cutting has rooted when it doesn’t wiggle if you gently tug on it.
Types of Summersweet
‘Hummingbird’
This slowly spreading, profusely blooming variety has a compact, mounding shape. It grows 2 to 4 feet tall and spreads 3 to 5 feet wide. Zone 3-9
‘Ruby Spice’
Unlike the species, ‘Ruby Spice’ has rose-pink flowers. It grows 4 to 6 feet tall and spreads 3 to 5 feet. Zone 4-8
‘Sixteen Candles’
For a compact summersweet that grows taller than wide, 'Sixteen Candles' is a good choice. It was named after its candle-like flower spikes and grows 4 to 5 feet high and only 2 to 3 feet wide. Zone 4-9
Summersweet Companion Plants
Ninebark
Ninebark shrubs are garden favorites primarily grown for their attractive bark that peels back in layers as the stems age. It is especially attractive in the winter when there is not much else in the landsccape to catch the eye. The traditional ninebark foliage color is a deep purple, but new foliage colors include gold and amber. Zone 3-7
Dogwood
If a dogwood tree is too large for your space, consider a dogwood shrub. It lets you enjoy many of the characteristics of dogwood but on a smaller scale. Several species native to North America produce flowers for local pollinators and berries for wildlife. Zone 3-8
Purple coneflower
Echinacea purpurea, the purple coneflower, is the most commonly found Echinacea species. The big blooms of this native plant are made up of a brownish-orange central cone and a ring of long, slender petals with a pinkish-purple hue radiating out from it. The landscaping options for planting coneflower are almost limitless as long as you plant it in full sun. Zone 3-9
Frequently Asked Questions
Is summersweet toxic to dogs?
This shrub hasno known toxicity to pets or humans.
Is summerweet an evergreen?
No, it is a deciduous shrub that loses its leaves in the fall after they turn into an attractive yellow golden or golden brown.
