Clethra alnifolia – also known as Summersweet

Clethra alnifolia is a native shrub that has spread from the Eastern United States, all the way up to Canada and down to North Florida. This shrub typically grows around wet areas in its native habitats. But in the wild, they can be found around swamps, Damp thickets, and sandy woods. 

Clethra Foliage

Clethra is a four-season plant. Its leaves have beautiful green foliage in the spring. And has alder-like foliage. The word Clethra comes from the Greek word “Clethra” which gives the meaning “alder tree”.

Common Names

Clethra is known by many common names. Among them, Coastal Sweet Pepperbush, Hummingbird plant, White Alder, Summersweet Clethra, and Summersweet are more often.

Nature

Summersweet or Clethra alnifolia blooms in clusters around mid-late Summer. Also, these shrubs can keep flowering while staying under full sun or part shade. Or even under a complete shady condition, they can keep blooming.  This is a unique property of Clethra, as lots of shrubs bloom typically during the spring or early summer normally. This means Summersweet will keep blooming long after a lot of shrubs and plants have already finished their flower blooming. 

A full-grown Summersweet shrub will get to 4-6 feet in height and maybe 3-5 feet in width.

When the shrub keeps growing, there may be an instance where suckers are growing from the base. On those occasions, if you wish to grow the shrub as a single shrub, then you can remove those extra suckers. 

But if you wish to grow the shrub as a colony of Summersweet, then leave them to be developed in the space freely.

In the Fall, pretty much all Clethra varieties put on a big show by changing to some sort of fall color. Summersweet tends to have a bit of gold color in the fall season. I guess you might call it yellow. But in shrub leaves, there is some sort of a honey brown color fall foliage on it. 

In wintertime, the shrubs have pretty nice bark, even without having leaves on branches.

Pollinator behavior

This shrub is one of the best pollinator-attracting shrubs you can ever find in the market. It is because the pollinators absolutely go crazy due to the beauty and fragrance of the summersweet flower. 

If you have a Summersweet shrub in your garden, the pollinators like bees and butterflies as well as hummingbirds will be fed enough during the summer. It happens because the Clethra has many bloom clusters to feed than the cultivars. And when the blooms fade away, the shrub produces seeds that eventually provide food for birds throughout the wintertime.

Therefore you will never have a problem with the lack of pollinators in your garden. 

How to plant a Summersweet Clethra?

If you wish to plant a Summersweet in your garden or landscape, then I strongly suggest planting it by relocating a Ruby Spice shrub that has already been farmed on a pot. Because it’s easy in that way as the shrub has grown to some point. You can easily buy that kind of already farmed Summersweet pots from an online store or from a local gardening shop.

And if you wish to follow the above method, then what you just have to do is dig a hole in your garden area or landscape and plant the shrub’s rootball by removing the pot.

Caution:
 When you are digging the hole, please make sure the height hole is the height of the pot.  And three to four times wide as the root ball. This will help the roots of the shrub to propagate in free space easily.

 Then, cover the rest of the hole with the rest of the soil. Then cover the top of the ground with a layer of compost which has 1-2 inch minimum height.

Caution: 
 Please Do not compress the soil in the hole and compost layers by stamping. Instead, keep it light. In that way, it will help the soil to store some extra moisture after watering the plant.

After completing all these steps, please mulch the free space around the shrub. This will help soil around the shrub to regulate temperature and moisture and especially to avoid weed growing around it.

how to Prune and Maintain Clethra alnifolia

The maintenance that is needed for the shrub is very low. The shrub will gradually grow its own. Since most likely the flowers bloom on new wood, you can prune shrubs according to your wish by late winter (By using a pruner) or early spring before the flower buds form.

If you are not sure what branch you should be pruning, as you cannot identify whether the component is dead or alive. Then try breaching an edge of the branch. If the inside of the breached part is white, then it’s alive. And also fertilize the soil at the same time.

Best 5 Native Clethra Cultivar types that grow Commercially.

There are several types of cultivars of Summersweet Clethra that are available in garden centers, online stores, and mail-order catalogs. These cultivars are varied from the wild Clethra alnifolia. As some of them are floriferous( making more flowers), have different color combinations such as pink and white while the original wild Summersweet has white and tall. Some of the commonly available clethra(Summersweet) cultivars are listed below.

• Ruby Spice – This shrub is used to give more clusters of flowers in pink-white color. And it has the darkest pink selections. The Flower cluster grows from 3 to 4 inches in height. And the fully grown Ruby spice has 6 to 8 feet in height and up to 6 feet in width. 

• Pink Spires – This shrub has pink buds that give a soft shell pink when it opens. The Flower cluster grows from 3 to 4 inches in height. And the fully grown Ruby spice has 6 to 8 feet in height and up to 6 feet in width.

• Hummingbird – It has a 4 to 6 inches long fragrant cluster of white flowers. This shrub is more like a dwarf one as it only grows up to 30 to 40 inches in height.

• Sixteen Candles– Another Dwarf variant that grows from 30 to 40 inches in height. The flowers bloom in white color from 4 to 6 inches in length. And it is somewhat floriferous( Blooms more flowers). This cultivar tends to hold the inflorescence more upright compared to the Hummingbird variant.

• Vanilla Spice– White variant like normal Summersweet. But this grows more like ruby spice into a height of 6 to 8 feet and 3 to 5 feet wide. Specialty in this cultivar is that it has extra large white flowers.

Problems that you may face while farming Summersweet Clethra

1. Insects

This shrub does not have many insects or disease problems, just like some other shrubs do. But sometimes, during the late-season rainfall, the foliages may become infected with Pseudocercospora leaf spots. Since these spots may occur in the late season, raking and disposing of fallen leaves will be enough to prevent the shrub from infecting.

2. Why didn’t my clethra produce flowers?

As I noted above, clethra has great tolerance against full shade conditions. But this will affect the flowering of the shrub. If you can arrange the environment so that the shrub can receive half a day Sunlight and keep the ground moist high to a certain point, then this will help the shrub to bloom more flowers.

Final thoughts…

It is better to water them well and, wait till the soil and plant get so dry for the next round. Because it will help the plant to adapt to the weather and soil conditions of your area, and increase endurance. And also this will provoke the shrub to root out into the surroundings and have a solid foundation from the inside of the ground.

As discussed above, Clethra alnifolia,

1. Is an excellent Native shrub 
2. Gives Beautiful Flowering
3. Has Attractive fragrant
4. Highly helps in Pollinator attraction
5. Has Fall color-changing leaves

Hence,  I believe it is worth planting some of these shrubs in your garden.