Native Flowering Shrubs

The missing middle

Look at a typical suburban yard in section: mown turf at the bottom, a few tree canopies at the top, and nothing between.

Look at a woodland edge and there are four layers: ground, herbaceous, shrub, and canopy. The shrub layer is where a large share of songbirds nest, where small animals move under cover, and where much of the fruit is produced.

Adding shrubs does more for a yard's habitat value per plant than almost anything else, and it also solves the design problem of a garden that looks flat in winter.

Buy them for what they do in four seasons

A shrub occupies its space permanently, so evaluating it on two weeks of flower is the wrong basis.

Arrowwood viburnum flowers in May, fruits blue-black in fall, and turns burgundy. Ninebark flowers, holds red seed heads, and peels its bark for winter. Oakleaf hydrangea flowers, colors deep wine, and exposes cinnamon bark. Winterberry does its best work in January. Red-twig dogwood is grown almost entirely for what it looks like in February.

Ask what a shrub is doing in each season before deciding where it goes.

The buying details that decide whether it works

Three things are worth knowing before you spend the money.

Some species are dioecious, meaning individual plants are male or female and only females fruit. Winterberry, inkberry, and spicebush all are, and a planting of all females produces nothing. Winterberry additionally needs a male whose bloom time matches.

Other species are not dioecious but fruit far better with cross-pollination, including arrowwood viburnum and American beautyberry. Plant two or more, and preferably not two copies of the same named clone.

And pruning timing depends on where flower buds form. Species that flower on old wood, such as oakleaf hydrangea and crossvine, set next year's buds this summer, so a late-winter cutback removes the whole display. Species that flower on new wood, such as smooth hydrangea and American beautyberry, can be cut hard in late winter with no loss.

Cultivars, and where to be careful

Named selections are convenient and often better behaved than wild forms. Two cautions.

Fully sterile flower forms, particularly mophead hydrangeas, produce no usable pollen or nectar. They are decoration rather than habitat.

Purple- and gold-leaved selections of native shrubs have in several studies been measurably less usable to leaf-feeding insects than the green wild type, which matters given that caterpillars are what nesting birds feed their young.

Where a shrub is meant to work rather than only to look good, the straight species is the safer purchase.

Sources: Doug Tallamy and University of Delaware research on native woody plants, cultivars, and caterpillar use; Mt. Cuba Center (native shrub trials including Physocarpus, Hydrangea, and Ilex); Lady Bird Johnson Wildflower Center, University of Texas at Austin (species profiles and pollination requirements); Cornell Lab of Ornithology (nesting habitat structure).