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Great Gardening By Sally Cunningham: In praise of shrubs

Plants from every category play important roles in our gardens. Flowering annuals and tropical plants are colorful and exciting all season long. Perennials flower for fewer weeks usually, but they offer variations in green the rest of the time. Then they give us the gift of their return in spring. Trees benefit us all: shading and cooling, housing the birds, defining and framing our landscapes. But how about the lowly shrub?

Shrubs often work in the background and are taken for granted – less dominant, less praised and less noticed, except for some show-offs (those hydrangeas!) that command applause. But a garden or landscape without shrubs is a vista without a horizon. Shrubs complement the other players; they complete the scene. Let’s pay homage to our shrubs.

Bush? Little tree?

The word “shrub” produces different images in individual brains. I have learned this upon offering to show homeowners plants in the shrub department. “No, I want the green bushes,” they’ll say, or “the round ones with flowers.” If I show them a spectacular multi-stemmed Doublefile Viburnum or rust-colored Ninebark, I might hear, “Oh but we need them short. Can we keep them trimmed?”

Let’s get the terms straight:

• A shrub is a multi-stemmed plant, evergreen or deciduous, with a woody base.

• Unlike herbaceous perennials that mostly die back to the ground in winter, shrubs remain above ground in the winter, whether or not they drop their leaves.

• We put a few shrubs in a different category (sub-shrubs or woody perennials) because they die back to the ground in cold climates, rather like perennials: Butterfly Bushes (Buddleias), Caryopteris, Hardy Hibiscus and Lespedezas among them.

• Woody plants with single trunks are called trees. Some may be dwarf trees and are often commingled with shrubs since they do the same landscape jobs. (You can limb up some shrubs to shape them into tree form. Other shrubs are grafted to create tree forms – “standards,” such as Hydrangea trees.

• Bush is not a true horticultural term in the landscape world; we sound smarter if we drop it.

The most important lesson of all, to help you choose plants better and have a generally more fulfilled existence: Any plant – hosta or hydrangea, spruce or Japanese maple – has a mature height and width. Choose a plant that will fill the spot you are offering without outgrowing the space. If you have a window 4 feet from the ground, choose a shrub that will not grow taller than 4 feet. Pruning (or, grrr, hacking back or trimming) shrubs or trees to make them shorter is not the answer. It is lots of work and usually produces a less attractive or less healthy plant than the plant that would have fit the spot naturally.

Beautiful and useful shrubs

I have favorites and opinions, colored by personal experience and by observing them in nurseries and other people’s gardens. My recommendations are only good if the plant is right for the site, and if your planting and care are right for the plant. I’m not mentioning species or cultivar names unless they are necessary to get the suitable plant. Nor am I showing plant sizes because they vary so much. Look at these plants in a nursery; read about them; then plant them and live with them.

• Callicarpa (Beautyberry): Stunning with late-summer violet to magenta berry clusters.

• Calycanthus floridus (Carolina allspice, sweetshrub or spicebush): Glossy leaves, maroon flowers; newer cultivars have larger flowers in lighter colors: ‘Venus’ and ‘Aphrodite.’

• Caryopteris (Blue mist shrub, bluebeard): May die back to the ground in winter but it is quite hardy; blue misty flowers on top of blue-gray or gold leaves.

• Clethra (Summersweet): Sweetly fragrant in midsummer, with pollinator-pleasing white or ruby bottlebrush style flowers.

• Deutzia: Wide-ranging sizes; pink or white spring flowers with fragrance; great introductions include ‘Chardonnay Pearls.’

• Enkianthus campanulatus (Red-veined enkianthus): Reddish stems and bell-like flowers; a compact, elegant, upright plant; requires soil acidity.

• Hibiscus moscheutos (Hardy hibiscus, swamp rose mallow): Dinner plate-sized flowers, new 3 to 6-foot cultivars; dies back in winter; slow to leaf out in spring but trust them to return. (Surprisingly, they thrive in swampy conditions.)

• Hibiscus syriacus (Rose of Sharon): From huge classics to newer shorties (‘Lil Kim’ and ‘Lil Kim Violet’).

• Hydrangea quercifolia (Oakleaf hydrangea): Among the most useful and treasured shrubs, with beautiful flowers; tolerant of partial shade, wine colors in fall – now with dwarf cultivars and the Gatsby series with even brighter fall color.

• Itea (Virginia sweetspire): Sweet bottlebrush, fragrant flowers; red leaves in fall.

• Lespedeza thunbergii (Bushclover): Little known late-season bloomer with arching stems that are covered in magenta flowers. Give it space but try it.

• Ligustrum (Privet, golden vicary privet): Used for hedges, privet is so much more if left to flower and become its natural shape. Make the pollinators happy!

• Physocarpus (Ninebark): Large plant with copper-toned leaves all season, but newer ‘Tiny Wine’ and ‘Lil’ Devil’ are petite.

• Sorbaria, the species or cultivar ‘Sem’: Vigorous suckering shrubs (great hedges or edges); lacy foliage; white flowers for pollinators. ‘Sem’ opens with pink leaves early in spring.

• Symphoricarpos (Snowberry): White berries. ‘Candy Sensation’ has pink berries.

• Viburnums: Irreplaceable genus with many wonderful species and cultivars. ‘Brandywine’ has multicolored berries and glossy leaves. ‘Darts Duke’ has great leathery leaves, shade-tolerant. Full-sized and dwart Doublefile Viburnums have beautiful structure, fall color.

I did not mention so many great workers: weigelas, St. John’s wort, Buddleia, mock orange and Fothergilla among them. We will speak of evergreen shrubs another time. But, for now, the show-off is calling. Read on.

Divas of August: Panicle hydrangeas

Wherever landscapers and gardeners have planted flowering shrubs, you’ll see panicle hydrangeas (Hydrangea paniculata). They are spectacular this year. They are overflowing with huge white or pinkish flowers and are 5 to 9 feet tall. They could not be more gorgeous. And the great news is that they are easy to grow, with minimal effort. No worries about whether they will flower or not. They do flower, sometimes in late July, always in August.

Your only difficulty – among panicle hydrangeas or the shopping list of shrubs – will be which ones to choose.

Sally Cunningham is a garden writer, lecturer and consultant.