Clethra alnifolia

My pick for June's Wildflower Wednesday is one of the most industrious shrubs in our summer garden, Clethra alnifolia, commonly referred to as summersweet. This stunning shrub is thriving in our rain garden as well as a few other garden beds. We grow the straight species, which adorns white blooms and 'Ruby Spice' with pink flowers. Preferring moist soil, this shrub is found naturally along stream banks, marshes and swampy woodland areas.  

Clethra alnifolia 'ruby spice' in rain garden with rudbeckia and Southern Shield fern

Blooming in July, it provides high quality nectar and pollen that brings in the pollinators. This is a great option for smaller gardens because it attracts such a wide variety of bees, wasps, butterflies, flies and hummingbirds. [more bang for your buck]

I enjoy observing all the pollinator activity on the blooms. Large wasps lurch themselves from one flower to the next. Butterflies are more graceful in their approach, gliding gently onto the flowers while bees dance around the spikes in a hurried manner. 

For this post, I am sharing a few of the common wasps we see on the flowers and their contributions to our ecosystem. 

Double banded scolid wasps are solitary and often referred to as scarab hunters because they control the scarab beetle populations. Females dig into the soil to find a beetle grub, sting it and lay their eggs on the grubs. 

Potter wasps make tiny nests out of mud that look like jugs. The adult wasp controls caterpillar populations by paralyzing a caterpillar and inserting it into the pot where it has laid one egg. While developing, the larva feeds on the caterpillar before digging its way out.  

The great black wasp helps pollinate plants and control katydid, cricket and grasshopper populations in the garden. They are in the digger wasp family and lay eggs in underground nests. 

The common thread-waisted wasp is a relative of the mud daubber wasp and feeds on nectar and small insects. These parasitic wasps are beneficial as they feed on caterpillars, spiders and grasshoppers. They ambush their prey and immobilize them with a sting. They then carry their prey back to their underground nest and lay a single egg on the victim. 

Mosts wasps are not aggressive toward humans, however they can sting if threatened. We have learned to live peacefully with wasps and appreciate their contributions as nature's pest control and pollinators.

Clethra alnifolia is unique because it flowers in shade when few other shrubs are blooming. It does, however, grow in sun as well and we selected full and part sun areas for our shrubs. Those in the sunny, rain garden are spreading more productively than other locations. This densly branching deciduous shrub makes an excellent screen and does respond well to pruning (best done in winter). 

The aromatic flowers, once pollinated, will produce dark brown seed capsules in the fall that often persist through the winter.

This shrub can be slow growing, but is easily propagated from stem cuttings in summer or from seed later in the year. This is an low-maintenance plant with a high wildlife value and definitely one to consider for your garden if you live in its natural range. (See USDA Plants Database) 

Be sure to visit Clay and Limestone for more wildflower contributions.