When Michael Rosenthal's Connecticut garden was profiled in Horticulture's July/August 2018 issue, he explained that the oceanside setting prompted him to seek trees and shrubs that could frame views of the water. At first he planted spring-blooming woody plants, but he later focused on those that could fill the midsummer color gap. He offered this list as some of his favorite summer-blooming trees and large shrubs:
Harlequin glorybower (Clerodendrum trichotomum): Drooping sprays of fragrant white flowers appear in late summer against a backdrop of broad leaves marked in two shades of green. It typically grows as a shrub but it can be trained to grow as a tree. It reaches 10 to 20 feet tall and wide. USDA Zones 7–10.
Japanese clethra (Clethra barbinervis): Long spikes of bee- and butterfly-attracting white flowers bloom at the end of the branches in midsummer, with a sweet fragrance. It grows as a large upright shrub or small tree 10 to 20 feet tall. Handsome bark provides winter interest. Zones 5–8.
Golden Spirit smokebush (Cotinus coggygria Golden Spirit, or 'Ancot'): The spring flowers are not showy, but their remains become large gauzy puffs in midsummer, inspiring the common name of smokebush or smoketree. Be sure not to prune this plant if you want blooms and subsequent "smoke." This cultivar has appealing lime-green leaves and vivid fall color. It is a multisetemmed upright shrub growing 8 to 15 feet tall. Zones 5–8.
Seven-son flower (Heptacodium miconioides): Panicles of fragrant white flowers occur from late summer to autumn, attracting butterflies and hummingbirds. This is a multi stemmed, vase-shaped shrub reaching 15 to 20 feet tall. Fruits with papery pink shells extend the display into fall and exfoliating bark provides winter interest. Zones 5–9.
'Natchez' crapemyrtle (Lagerstroemia indica xfauriei 'Natchez'): Read our post dedicated to this plant.
'Edith Bogue' magnolia (Magnolia grandiflora 'Edith Bogue'): Lemony-scented eight-inch-round flowers open in mid- to late summer against large, dark green leaves. This cultivar is said to have better winter hardiness than the species and other selections. It can grow 40 to 60 feet tall, with a rounded crown to 30 feet wide. Zones 6–9.