Summersweet clethra is a deciduous shrub that is native to eastern North America. It typically grows to 6-8 feet tall and produces white or pale pink flowers in the summer. The foliage of the plant is dark green and turns yellow-brown in the fall. Summersweet clethra is an attractive plant for use in shrub borders or as a specimen plant. It is also tolerant of a wide range of soils and prefers full sun to partial shade.
Related plant:
Hummingbird Summersweet Shrub
Related plant:
Vanilla Spice Summersweet
About soil condition, Summersweet Clethra prefers average, moist, well-drained soils, but it is tolerant of a wide range of conditions, from wet to dry. It also does well in sandy or gravelly soils. It is not particular as to pH.
Similar to other sun-loving plants, Summersweet Clethra needs at least six hours of direct sunlight each day to thrive. If you live in an area with hot summers, it's best to plant this shrub in a spot that gets some afternoon shade to protect it from the intense heat.
The temperature condition that is most favorable for Summersweet Clethra is warm weather. This plant grows best in full sun to partial shade and soil that is moist to wet. It is tolerant of salt and clay. Summersweet Clethra can be pruned in late winter to early spring.
Ideal humidity condition for this plant is 50% and above. If the humidity is too low, the leaves will begin to drop and the plant will go into shock. Also, the plant will become leggy and the blooms will be less showy.
The fertilizer, usually the plant food, is mixed with the soil to provide the essential nutrients that the plant needs to grow. The roots are the part of the plant that anchor it in the ground and absorb water and minerals from the soil.
Pruning Summersweet Clethra is best done in late winter before new growth begins. You can prune Summersweet Clethra to keep it from getting too leggy, to remove dead or damaged branches, or to shaping it. When pruning, make sure to make clean cuts at a 45-degree angle just above a node.
Propagation is typically done through root cuttings taken in late winter. The cuttings should be 2-3 inches long and taken from young, healthy plants. Cuttings can be placed directly into moist soil or started in containers filled with a well-drained, soil-less potting mix. Once roots have developed and the plants are actively growing, they can be transplanted into the garden.
Usually, the plant growth rate is relatively fast when the plant is young. Once the plant becomes established, its growth rate will naturally slow down some. However, if given the proper conditions, such as moist soil and plenty of sunlight, the plant will continue to grow at a relatively fast pace.
Common problems for this kind of plant are powdery mildew, leaf spot, and root rot. The best way to avoid these problems is to plant your clethra in well-drained soil and to water it regularly. If you see any signs of these problems, such as powdery mildew on the leaves or leaf spot, you should treat the plant with a fungicide as soon as possible.
Source:
Summersweet - Clethra alnifolia - PNW Plants - Washington
Growing Summersweet Clethra in the Home Landscape
Clethra alnifolia: Sweet Pepperbush | College of ... - clemson.edu
