May Flowers & Foliage

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Oh, my aching muscles...

For Maximum Color

By Pam Richards

In the Pacific Northwest in May, rhododendrons reign. When these divas burst on stage to sing their aria, all around them becomes secondary.  They demand and deserve our attention and applause.

When I first began gardening, I lived across the street from a man who had grown his six-foot-tall rhododendrons from seed.  In May, brilliant red and yellow flowers half-obscured the shrubs lining the north side of his house. Blooming columbine and a montana clematis accompanied them. “I can’t let the rhododendrons bloom alone,” my neighbor said, offering me my first design lesson.  “They’re the main attraction, but they need some company.”

I took his advice and planted a large group of columbine at the foot of a small rhododendron—and a clematis to climb a trellis behind it.  The shrub’s elaborately ruffled, hot pink flowers were the main attraction, with the pale pink clematis and tall columbine as the supporting cast.

Rhododendrons are dense and dark and rigid, so I like to contrast them with movement and delicacy.  Some of my favorite rhody sidekicks are:

Millium  effusumAureum’—golden wood millet. Providing a bright spot in the shade, this grass’s chartreuse leaves vibrate against dark green. Other yellows to consider are the variegated holly fern, Arachniodes simplicior ‘Variegata’ with its lemon-yellow stripe, and Corydalis lutea, with deep yellow flowers and ferny foliage.

The pretty, pendulous flowers of bleeding hearts are lovely under rhododendrons. And the airy flowers of heuchera (coral bells), atop a colorful rosette of leaves, are a perfect companion.  HeucheraReginaand H. Ruby Mist have pink flowers and silver frosting on their dark leaves. 

The heuchera cultivars with delectable food names and leaves in shades of yellow, orange, peach and amber blend well with
orange or yellow flowers.

Rhododendrons have shallow roots that resent disturbance, so do not plant directly beneath them.  Treat the root zone to an acidic fertilizer and mulch lightly—peat moss is great.  Then plant companion perennials around the shrub’s drip line.  Water deeply and make sure the perennials, whose small roots compete with the larger, thirsty roots of the rhododendron, get the water they need through the growing season.  The shrubs and their companions enjoy morning sun and afternoon shade.

Fun in The Sun

May offers more floral abundance than just the rhododendron, however.  Rosa banksiae (Lady Banks’ rose) is an exuberant rambler that blooms white and scented (‘Alba Plena’) or yellow and scentless (‘Lutea’).  It will cover the wall and roof of a garden shed, most of a fence, or a large arbor.  Lady Banks’ rose has few thorns, is resistant to disease and insects, and is clothed in flowers in late spring.

Either white or yellow roses would set off a dramatic black-leafed physocarpus (ninebark) or sambucus (elderberry).  Both are large shrubs with spring, summer and fall interest.  Along with the white rose, add full white peonies like Festiva Maxima with lipstick red markings, and the sedge Carex morrowii ‘Ice Dance’

with green and white striped foliage. (The sedge needs to be divided every year to remain attractive.)  Include Geranium phaeum, the mourning widow cranesbill, with tiny black flowers and black markings on the leaves, and you will achieve a casual yet urbane vignette.

The yellow Banks’ rose is a good background for some chocolate.  A group of the columbine Aquilegia ‘Chocolate Soldier’ will add interest and scent.  Mounding grasses Carex comans ‘Milk Chocolate’ and Carex tenuiculmis ‘Cappuccino’ are as seductive as their names suggest.  Edge the planting area with Tiarella ‘Mint Chocolate’, a low-growing perennial with maple-tree leaves marked with chocolate brown.

One of my May favorites is the oriental poppy.  Grow an orange poppy with orange flowering geum and Carex testacea, a brown sedge with a scattering of glowing orange blades. Turn a spot of garden into a Fred Astaire/Ginger Rogers movie by planting black-flowering Iris chrysographes and a black-leaved heuchera with Papaver orientale ‘Royal Wedding’, whose white tissue-paper petals are lightly dusted with dark flecks.

The only drawback to oriental poppies is that they disappear completely once they have finished blooming.  I surround poppies with perennial geraniums that will weave through garden beds from May to the end of September.  I plant boltonia (a type of aster) behind the poppy. By the end of May the boltonia will begin to swell and as summer proceeds it will fill the empty space with flowers.

Finally, the willow Salix integra ‘Hakuro Nishiki’ trained to a standard will anchor a collection of plants.  The willow has white leaves marked with green and pink. A pink, early-blooming rose such as ‘Dainty Bess’ will play up the willow’s pink markings. 

Pair the rose with a single-petaled pink peony and underplant it with white flowering allium.  Scatter small, white and scented Anemone sylvestris beneath the willow.  Let Geranium x cantabrigiense ‘Biokovo’, with pale pink on white flowers and the scent of the woods, wander.  Carex ‘Frosted Curls’ will provide evergreen interest in the winter when the willow loses its leaves and the branches turn red in the cold.

Settle an old, silvery-gray wooden bench near the rose, under the willow, among the geraniums—and in May you will have a lush, colorful spot in the garden.  NWGN

Pam owns Pamela Richards Garden Design in Seattle, reach her at 206-781-2314; or



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