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, July, and August. Consider these shrubs to add color and interest to the garden in the summer.

Carefree Beauty Rose (Rosa ‘BUCbi’)
Carefree Beauty Rose (Rosa ‘BUCbi’)

Shrub Rose

The rose (Rosa spp.) is the quintessential garden plant. Beautiful, sometimes fragrant flowers bloom in June and then sporadically the rest of the growing season. Flowers are single or double in every shade of pink, white, red, coral, and cream. Hundreds of cultivars exist. Plant shrub or landscape roses, which are winter hardy and naturally more disease resistant than the finicky hybrid tea, grandiflora, and floribunda type roses.

Panicle Hydrangea

Panicle Hydrangea (Hydrangea paniculata) has become one of the most popular landscape shrubs available in the garden centers. Showy pyramidal-shaped flower clusters in a creamy white appear in July. As they fade, blooms turn to a pink or blush then finally a tan/brown color and hang on all fall and most of the winter. Unlike some of their shade-loving close relatives, panicle hydrangea grows in full to part sun. This species is one of the hardiest and most tolerant of all the hydrangeas. Dozens of cultivars exist, some with prominent pink flower color and dwarf growing habits reaching only half the size of a typical variety. Zone 3 to 8. 8-12’ tall and 7-10’ wide.

Oak Leaf Hydrangea (Hydrangea quercifolia)
Oak Leaf Hydrangea (Hydrangea quercifolia)

Oak Leaf Hydrangea

Native to the southeastern United States, Oak Leaf Hydrangea (Hydrangea quercifolia) has distinctive coarse, lobed leaves resembling oak leaves. The dark green foliage turns a great red color in the fall. White clusters of flowers appear in June and fade to pink as they age. Plants sometimes see some winter die-back which can reduce bloom count. Zone 5 to 9. 6-8’ tall and wide.

Smokebush

Smokebush (Cotinus spp.) has flowers with billowy clusters of pink to yellowish-white flowers from May to July. Plants often have colorful leaves with cultivars featuring purplish-burgundy or chartreuse leaves instead of the more typical dark green. Shrubs 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

A large suckering shrub, Bottlebrush Buckeye (Aesculus parviflora) is excellent for the back of the perennial border, providing a dark green backdrop for the garden in front of it and then creating a show of its own when it blooms. Upright white panicles of flowers appear in June and July. Grow this southeastern U.S. native in full sun to part shade. Zone 4 to 8. 8-10’ tall and 8-15’ wide.

Bottlebrush Buckeye (Aesculus parviflora)
Bottlebrush Buckeye (Aesculus parviflora)

New Jersey Tea

This relatively unknown eastern North American native shrub is a great addition to the garden. New Jersey Tea (Ceanothus americanus) blooms in clusters of white flowers from May through June. Plants do great in otherwise difficult locations. Zone 4 to 8. 3-4’ tall and 3-5’ wide.

Buttonbush

Buttonbush (Cephalanthus occidentalis) prefers and thrives in wet conditions making it the perfect addition to a low-lying area, rain garden, or otherwise wet location where many other shrubs don’t do well. Blooms are white, ball-shaped, and hang like planets from the branches in June. This North American native shrub is also a wonderful plant for butterflies and other pollinators. Zone 5 to 9.  5-12’ tall and 4-8’ wide.

Carolina Allspice

A Southeastern U.S. native equally at home in sunny or shady locations, Carolina Allspice (Calycanthus floridus) has a flush of blooms in May and June and sporadic flowers through summer. The flowers are 2 inches across, reddish-brown to maroon in color, and feature an intense fragrance that smells like a mixture of strawberry, pineapple, and banana. Reliable yellow fall color makes this a great multi-season, multi-sensory shrub for the landscape. Zone 4 to 9. 6-10’ tall and 6-12’ wide (larger in the shade).

Rose of Sharon

Rose of Sharon (Hibiscus syriacus) is an upright shrub with beautiful hibiscus-like flowers 2 to 4 inches across from July to frost. Dozens of cultivars are available with single and double 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.

Rose of Sharon (Hibiscus syriacus)
Rose of Sharon (Hibiscus syriacus)

Summersweet

Summersweet (Clethra alnifolia) blooms in panicles of fragrant white (sometimes pink) flowers in July & August that the bees and butterflies love. Native to eastern North America, plants tolerate a wide range of conditions. Plants grow and bloom best in part-shade but tolerate other light levels well. Zone 3 to 9. 3-8’ tall and 4-6’ wide.

False Spirea

An excellent shrub for colonizing otherwise tough locations like a hillside, False Spirea (Sorbaria sorbifolia) spreads readily by suckers. Plants tolerate a wide range of soil and light conditions but do best in organic, moist, well-drained soils and full sun. Be prepared to contain its spread in these ideal conditions. In June and July, panicles of white flowers appear. Zone 2 to 8. 5-10’ tall and wide.

Spirea

Spirea (Spiraea spp.) can be found in almost any garden center. Dozens of cultivars have a variety of showy pink to white clusters of flowers May through July. Plants are easily grown in various conditions, making them very popular. Zone 3 to 8. 1-3+’ tall and wide, depending on the cultivar.

Shrubby Cinquefoil

Shrubby Cinquefoil (Potentilla fruticosa) blooms June to frost with five-petaled flowers in yellows, reds, oranges, and creams. Shrubs grow in a wide range of conditions and can get a little ragged with age. Cut back hard in spring to rejuvenate when they look “tired.” Zone 3 to 7.  2-4’ tall and 3-5’ wide.

Buttonbush (Cephalanthus occidentalis)
Buttonbush (Cephalanthus occidentalis)

Carolina Allspice (Calycanthus floridus)
Carolina Allspice (Calycanthus floridus)

 

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