How to Plant, Grow, and Care for Coastal Pepperbush
If you’re looking for a deciduous shrub that not only survives but thrives in sometimes harsh coastal conditions, then look no further than coastal pepperbush. This hardy perennial is low maintenance and produces beautiful blooms during the summer. Gardening expert Kelli Klein shares all you need to know about growing coastal pepperbush.
Coastal pepperbush is the unsung hero for coastal gardeners looking for a perennial shrub to plant along with flowers in sandy soils and coastal environments (it will even tolerate salt spray). Also known as coastal sweet pepperbush or summersweet, this North American native plant is an attractive ornamental for the garden.
This deciduous shrub is perfect for borders and tolerates being shaped into a hedge. As a bonus, it also produces stunning flowers that attract many pollinators! As the flowers die back, they will form small seed pods resembling peppercorns, which act as a food source for small mammals.
Plant Type Perennial
Species Clethra alnifolia
Native Area North America
Exposure Partial sun
Height 5-10 feet tall and wide
Watering Requirements Prefers to remain moist
Pests & Diseases No major pest or disease
Soil Type Sandy
Soil pH Acidic
What Is Coastal Pepperbush?
This perennial shrub is native to swampy woodlands, wet marshes, stream banks, and seashores. As its name would suggest, this species often grows in sandy soils along the coast. The native habitat of pepperbush includes southern Nova Scotia and the northeastern coasts of the United States to the Gulf.
This deciduous shrub produces fragrant white flowers that bloom throughout the summer. The blooms also produce nectar, which attracts hummingbirds and butterflies. The flowers die back to reveal dry brown capsules which contain the seeds. These capsules are slightly similar to peppercorns, where the name “pepperbush” comes from. Although this plant is not toxic, it offers more ornamental than culinary value.
Coastal pepperbush is gaining popularity as a landscaping plant, but some gardeners find it challenging since it tends to leaf out later in the season. It can, however, add interest to a mixed garden and help provide blooms just around the time that early spring bloomers begin to peter out.
The fact that it forms sizable clumps in its native habitat makes it a great filler or backdrop for large, previously uncultivated landscape areas. Its recent popularity has resulted in the cultivars, ‘September Beauty’ and ‘Ruby Spice.’ Most pepperbush varieties have white flowers, but ‘Ruby Spice’ showcases beautiful pink flowers.
As mentioned above and as its name would suggest, coastal pepperbush is native to coastal areas in North America. More specifically, its native area includes the coasts of Nova Scotia and Maine, south to Florida, and west to Texas.
You can also find it in swampy woodlands, wet marshes, stream banks, and seashores. This makes it an excellent border plant for a backyard pond to help prevent erosion.
This is a tall, many-branched deciduous shrub with upright clusters of white flowers. Its oval-toothed leaves turn orange or yellow in the fall just before they drop for the winter. As the flowers fade, brown pods resembling peppercorns appear on the plant through the winter and act as forage for some small animals.
It handles pruning and shaping very well, making it a great border plant. Its later bloom time makes it great for providing a pop of color when earlier season blooms are beginning to fade. It provides interest all season long until the winter when it drops its leaves and enters dormancy.
Where To Buy
If you live in a coastal area, you can find this shrub at a local nursery. Outside of the coast, it hasn’t gained popularity just yet! If you don’t have any luck, check out online nurseries that supply other trees/shrubs. You can also find pepperbush seeds online. However, it’s much easier to start with an established plant.
Once you’ve obtained your coastal pepperbush, you probably wonder how and when to plant it. Two times of the year are optimal for planting pepperbush. Plant in spring or early fall.
If you live in a warmer climate, it is easier to plant in the fall as the weather is cooling off to spare your pepperbush from suffering through a sweltering summer during its first year. If you live in a milder climate, planting in the spring is fine. The main goal is to establish your pepperbush before winter frosts arrive, so plant it at least six weeks before your first frost.
How to Grow
Pepperbush is relatively easy to grow but has a few specific requirements. It tolerates pruning and edging, which makes it perfect for a privacy hedge.
Coastal pepperbush does best in full sun but tolerates partial shade conditions. They will benefit from afternoon shade in hot climates or in regions with prolonged periods above 90 degrees Fahrenheit.
You still want to be sure that your pepperbush receives at least 6 hours of direct sunlight per day, but the hours do not need to be consecutive. This means it can receive 3 hours of the morning sun, shade during the hottest part of the day, and then 3 hours of the evening sun. In ideal temperatures, pepperbush does best in dappled sun conditions.
If you provide plenty of water, Pepperbush grows quite large and even puts out suckers to remove and replant elsewhere. This shrub does best when it is provided with consistently moist but not waterlogged soil.
Although pepperbush does not prefer to dry out between waterings, it can handle brief drought and/or flooding periods once established. Mulching during hot and dry periods will also help the soil retain moisture.
Coastal pepperbush grows naturally in poorly drained, consistently moist soils and can thrive in sandy coastal conditions. Adding organic matter, compost, and mulching can help the soil maintain the consistent moisture that this shrub prefers.
Pepperbush also prefers acidic soil conditions, similar to that of blueberries, azaleas, and hydrangeas. If you need to alter the pH of your soil, you can add a soil acidifier to the planting site or purchase pre-acidified soil for acid-loving plants. The optimum pH is 4.5 for pepperbush.
Temperature and Humidity
Coastal pepperbush is well suited for USDA growing zones 4-9, where it can survive temperatures as low as -22 degrees Fahrenheit during the winter while the plant is dormant. These deciduous shrubs need a period of dormancy (also called chill hours) to profusely bloom during the following growing season. Their seeds require cold stratification to germinate as well.
Conversely, they may struggle in the heat, and, as mentioned above, they do better when provided with more shade in hot climates. However, it can tolerate various sun conditions from full sun to almost complete shade.
This shrub will not accept a consistently hot and dry site. Spreading mulch around the root zone (not right at the tree’s base) and watering well during prolonged temperatures over 90 degrees will help. As a coastal plant, it prefers some humidity and moisture in the air but is quite adaptable and can survive without it.
In early spring, provide your pepperbush with a slow-release fertilizer. This will help the plant break dormancy and put on plenty of new growth and buds for future flowers.
This is also a great time to test the soil pH and see if it needs to be adjusted again for the upcoming growing season. You can also add a side dressing of organic matter or compost instead of fertilizer.
Pruning your pepperbush is not required, but it is recommended as it can grow vigorously and unruly quite quickly in optimal growing conditions. You’ll also want to prune to remove damaged, diseased, or dying branches.
Pepperbush can be pruned into a hedge if being used for a border. Ensure you also prune in spring to promote new growth and shape the shrub.
Growing In Containers
When growing in containers, add sand to the soil to mimic its natural habitat. The dwarf variety, ‘Hummingbird,’ is exceptionally well suited for containers. You will occasionally need to repot your pepperbush.
If you notice a lack of new growth and the roots have begun to swirl around the edges of the container, then it is time to repot. When repotting, choose a pot that is at least 2 inches larger in diameter and water consistently until the plant has settled into its new home. When it begins to put out new growth, this is a good sign that it is well established in the new container.
Coastal pepperbush can be started from seed planted in fall or spring. The seeds have a higher germination rate when given a period of cold stratification, so seeds planted in the fall and allowed to overwinter have a better germination rate.
Greenwood cuttings can be taken in early summer, dipped in rooting hormone, stuck into a pot of dirt, and allowed to form roots. Once roots have appeared and the cutting begins to put out new growth, you are ready to transplant it into its new home either in a container or in the ground.
While this plant is relatively adaptable to various growing conditions, a few circumstances can cause issues to crop up. Read on to learn how to identify and remedy these issues before they become a larger problem.
Lack of Flowers
A lack of flowering is linked to a lack of sunlight. As mentioned above, coastal pepperbush does best in partial sun but still needs about 6 hours of sunlight per day.
Monitor the planting site throughout the day if your pepperbush is not flowering. If you determine that it is getting less than 6 hours of sun per day, it is best to move it to a sunnier spot.
Brown, Dry, Crispy Foliage
As mentioned above, coastal pepperbush prefers consistently moist soil. A lack of water can cause some growing problems.
Brown, dry, or crispy foliage is a sign that your pepperbush is suffering from a lack of water, especially during periods of extreme heat. Cut back any dead or damaged foliage, increase the water your plant is receiving each week, and the problem will be resolved.
One caveat, however: This is a deciduous plant that will drop its leaves every fall. If it’s autumn in your area, no amount of extra moisture will prevent your plant from losing its leaves, but that’s to be expected; it’ll create new ones in the spring.
One thing that makes coastal pepperbush an attractive choice for ornamental gardeners is the lack of pest issues. There are no major insect pests that plague pepperbush. However, deer have been known to munch on this deciduous shrub, but only if no other forage is available in the area.
Overwatering can lead to fungal issues like root rot. When your pepperbush is overwatered, the leaves will wilt and eventually drop. Root rot symptoms will appear as a soft, mushy stem, wilting, and rotten roots.
This type of rot is hard to recover from but can be remedied if fresh, white roots have not yet turned to mush. Cut back the rotted roots and replant into dry soil if growing in a container. If growing in the ground, allow the area to dry out before continuing to water.
Coastal pepperbush is an excellent low-maintenance perennial shrub to add to your landscape, especially if you garden in challenging coastal environments with sandy and acidic soil. It can, however, adapt to various conditions as long as the basic needs mentioned above are met. Once established, this plant will add interest to your fall garden with its beautiful blooms for years to come.