Early to midsummer is the time many herbaceous perennials reach their maximum sizes, as they mass together and flower in (hopefully) artful partnerships. I'm delighted whenever these plant pairings make sweet melodies together, especially if I have influenced the musical selection. But sometimes, harmonious matches have more to do with light, growing circumstances and just plain luck.
My garden has several areas of partial sun, so I'm always looking for plants that adapt well to changing light patterns. The silvery green leaves and lacy chartreuse blossoms of lady's mantle make attractive mounds from late May through August, and find a good companion in the lavender-blue flowers and bright cream-edged leaves of ‘Snow and Sapphires' Jacob's ladder. (Both plants appreciate a woodland soil with lots of humus, especially in bright sun.) I have these two at the base of a bronze-coloured lace-leaf Japanese maple (Acer palmatum var. dissectum), which makes a dramatic foil for the brightly coloured lady's mantle and Jacob's ladder. You can get the same effect by using a plum purple geranium such as Midnight Reiter, with startling violet-blue blooms. All the flowers in this grouping are small and frothy, and the play of light against dark leaves makes an interesting contrast in a small space.
I like the idea of light- and dark-coloured companion plants and have a sweeping curtain of deepest maroon ‘Purple Fountain' weeping beech (Fagus sylvatica) as a backdrop to trembling clouds of mauve ‘Hewitt's Double' Yunnan meadow rue. Flower spikes of pale pink, fairy-like ‘Canon J. Went' toadflax (which modestly seeds itself around the garden) are here, as is a strong stand of mauve ‘Kobold' blazing star to reinforce the vertical lines in this grouping. Lurking about this spot is an elusive white foxglove that some years shows itself with tall stalks of milk-white bells with naked, spotless throats.
Removing the grass from a small slope has given me a planting area in bright sunlight, with massive slabs of stone forming steps up the middle. Plants that ramble are useful here, and on one side of the steps I've squeezed in some sun-tolerant chartreuse coleus and two perennial geraniums: violet-blue Rozanne (with extra-large flowers blooming through November) and magenta-purple ‘Ann Folkard' (with chartreuse foliage). The geraniums tend to vine and scramble around. These mix it up with Clematis x durandii, a short, non-clinging species clematis with deep indigo blue flowers. (Shorter species and hybrid clematis are happy to sprawl and wander through other plants when a trellis isn't available, popping up to present their flowers.) Pale yellow ‘Moonbeam' threadleaf tickseed adds some height and warm colour, while strong punctuation is provided by a stand of school bus-yellow ‘Connecticut King' Asiatic lilies. On the opposite side of the steps is a big clump of ‘Morning Light' eulalia grass. Its pale green-and-white variegated blades make a soft background for the bicoloured, cherry red-to-pale pink ‘Paprika' yarrow. With them is the useful coneflower ‘Kim's Knee High', a dwarf cultivar (deep pink with an orange centre) adaptable to gentle slopes.
By late summer, the garden becomes a scene of pleasant chaos, with plants massed together, leaning and tumbling over, as the gardener scrambles to stake, tie and deadhead. (This gardener soon gives up and lets the plants have their way!) A reliable group in partial shade is anchored by a large ‘Frances Williams' hosta, its puckered, yellow-banded leaves forming a background for the delicate (yet also indomitable) mounding strands of green-and-creamy-yellow variegated Moor grass, which holds its purplish flowers well into autumn. Keeping close company are two plants that carry on despite misfortunes of weather or gardener neglect: the ‘Albomarginata' Japanese toadlily, its exotic white flowers heavily spotted with maroon; and the intense electric-blue willow gentian that Louise Beebe Wilder described in the story of her garden outside of New York City, Adventures in a Suburban Garden (1931), as “…weighted with glorious blue trumpets in late summer.” Both plants have similar architecture, making small clumps of 30-centimetre-tall wands, their flowers facing upward to greet the onlooker.