Great Summer-Blooming Shrubs for Iowa

The woody shrubs in our gardens help add structure, height, and create a backdrop for the colorful perennials in the garden. These staples don’t always play a supporting role in the landscape. While many woody trees and shrubs bloom in the spring, there are several great selections for Iowa that look their best in June and July. Below is a list of shrubs that will add color and interest in the summer.

Panicle Hydrangea (Hydrangea paniculata) – Showy pyramidal shaped flower clusters in a creamy white appear in July. Grow in full to part sun. Plants are some of the hardiest and most tolerant of the hydrangeas. Zone 3 to 8. 8-12’ tall and 7-10’ wide.

Oak Leaf Hydrangea (Hydrangea quercifolia) – White clusters of flowers appear in June and fade to pink as they age. The coarse, lobed leaves have great red fall color. Plants sometimes see some winter die-back which can reduce bloom count. Native to SE U.S. Zone 5 to 9. 6-8’ tall and wide.

Smokebush (Cotinus coggygria) – Blooms are billowy clusters of pink to yellow-ish white flowers in May to July. Plants often have colorful leaves and bloom on old growth, so don’t trim back in spring if flowers are desired. Zone 5 to 8.  10-15’ tall and wide.

Bottlebrush Buckeye (Aesculus parviflora) – Blooms June and July with upright white panicles of flowers. Native to SE U.S. Does well in full sun to part-shade. Zone 4 to 8. 8-10’ tall and 8-15’ wide.

New Jersey Tea (Ceanothus americanus) – Blooms in clusters of white flowers in May through June. Native to eastern N. America. Plants do great in otherwise difficult locations. Zone 4 to 8. 3-4’ tall and 3-5’ wide.

Buttonbush (Cephalanthus occidentalis) – Blooms are white, ball-shaped and hang like planets from branches in June. Native to North America. Prefers and thrives in wet conditions. Zone 5 to 9.  5-12’ tall and 4-8’ wide.

Carolina Allspice (Calycanthus floridus) – Blooms May to July with reddish-brown flowers with an intense fragrance. Native to SE U.S. Zone 4 to 9. 6-10’ tall and 6-12’ wide (with time).

Rose of Sharon (Hibiscus syriacus) – Blooms July to frost with showy flowers in white, pink, red, lavenders and bicolors. Plant in full sun for best bloom. Zone 5 to 8. 5-8+’ tall and 4-6’ wide.

Summersweet (Clethra alnifolia) – Blooms in panicles of white (sometimes pink) flowers in July & August. Native to eastern N. America. Plants like part-shade and tolerate full-shade well. Zone 3 to 9. 3-8’ tall and 4-6’ wide.

False Spirea (Sorbaria sorbifolia) – Blooms June and July in panicles of white flowers. Plants spread readily by suckers. Zone 2 to 8. 5-10’ tall and wide.

Spirea (Spiraea sp.) – Dozens of cultivars have a variety of showy pink to white clusters of flowers May through July. Plants are easily grown in a variety of conditions, making them very popular. Zone 3 to 8. 1-3+’ tall and wide, depending on cultivar.

Shrubby Cinquefoil (Potentilla fruticosa) – Blooms June to frost with five-petaled flowers in yellow, reds, oranges, and creams. Cut back hard in spring to rejuvenate when they look “tired.” Zone 3 to 7.  2-4’ tall and 3-5’ wide.

Prepared by Aaron Steil, Assistant Director  |  photo caption: Hydrangea paniculata ‘Tardiva’