GARDENS:Successful plant associations, whether they happen by accident or by design, can produce a stunning display, writes Jane Powers
I NEVER REALLY saw the point of white-flowered lavender until about three years ago. Why was there any need in the world for a bleached form of one of the most iconic and evocative flowers, I wondered. Lavender, to my then closed mind, was as much about the colour as anything else: the idea of the flowers being white seemed as incongruous as if they were to smell of roses.
But the great thing about having a closed mind (like Pollyanna, I prefer to see the bright side of everything) is the wonderful feeling of liberation and warmth when it is unexpectedly prised open. Such was the welcome sensation when on a summer's day at the Bay Garden in Camolin, Co Wexford, I saw white lavender paired with pinky-purple agastache. Suddenly, there was a raison d'etre for what had heretofore seemed like a lacklustre member of the lavender clan. Against the smoky grey-white murmur of the albino lavender spikes, the agastache sang out robustly.
The scented-leaved plant is not unlike a lavender itself, in flower-shape and colour - but larger and looser, a lavender-mimic in an oversized costume. This partnering of like with like (or rather, with almost like) is the kind of thing that makes a planting scheme come to life with a spirit far greater than the sum of its parts.
Another pleasing we-look-the-same-but-not-quite partnership, which I've seen in another garden, is Allium sphaerocephalon and Knautia macedonica: the first has deep-red, egg-shaped bobbles, while the second has slightly paler and flatter pincushions of flower. Both are borne on wiry stems at around the same height, and are roughly the same size, so they dance in step together in the breeze.
There are many other plants that bear kindred-to-each-other flowers, and that combine well. For instance, the yellow, orange and reddish late-summer daisies, Helenium, and perennial Helianthus (sunflower) can be planted together in an American prairie-esqe tableau. And purple asters are satisfyingly complementary when paired with any of the orange or yellow daisies that flower at the same time. Like (or like-ish) flowers, when cleverly commingled (with just the right degree of difference in colour, shape or size) can make a vibrant and stimulating planting.
Successful plant associations, however, often depend on other characteristics, such as the colour, shape and texture of the foliage, and plant habit (the way it grows) and weight. Flowers, after all, are the most ephemeral thing in a garden, and we would not want to be relying solely on them for visual entertainment. One of the most exquisite plant unions I've ever seen is in the Bay Garden (again), where Iain MacDonald has coupled stag's horn sumach (Rhus typhina 'Dissecta') with the pony tail grass (Stipa tenuissima). In the dead of winter, with nary a flower in sight, the two make a beautifully gaunt and spare alliance: the bare, brown branches of the one thrusting through the dried, buff-coloured sheaves of the other. (You can see exactly how this shrubby tree, a native of north America, got its "stag's horn" appellation: here it looks as if a herd of very short deer with long and elegant antlers have congregated in the long grass.)
The success of this plant marriage, as with so many, relies on contrasts: in this case there is the double whammy of dark against light, and bold and strong against soft and indistinct.
Dark against light can be used effectively on a more blocky scale, by using purple-foliaged plants (such as the shrubs Cotinus 'Royal Purple' or Dodonaea viscosa 'Purpurea') with silvery-leaved plants (artichoke, astelia) or blueish ones (some euphorbias, Macleaya). But because the eye tends to pause with every change between dark and light, this sort of colour combination should be used sparingly, and not continually repeated - unless one is aiming for a strobe-light effect on the eyeball.
Because we have more green foliage than anything else in the garden, some of the strongest and best combinations of plants rely on the leaves, with the flowers being an incidental bonus. Bold leaves, including those of Astilboides tabularis, bergenia, brunnera, Darmera peltata, hosta and ligularia look well when contrasted with the strappy leaves of plants such as crocosmia and iris, or the complicated and delicate foliage of plants such as ferns, astilbe, dicentra and meadowsweet. Just make sure that the plants you are matching are of equal vigour, and that they all enjoy the same kind of conditions.
Ornamental grasses, of all plants, beg to be partnered with other species. There is nothing so sad as a lonesome clump of Stipa, Carex or Calamagrostis in a municipally-planted, low-maintenance scheme, longing for another plant to show up its excellent vertical lines and athletic shape. Flat plates of flowers, such as achillea and large sedums, are perfect grass partners - especially for the tall and upright kinds.
The New Zealand brown Carex grasses, such as C. comans can look decidedly - well - brown on their own, but weave a dainty pinkish hardy geranium through them in summer, or a golden crocus in spring, and they come alive and shrug off their boring browndom. Pale pink, pale purple, peach, yellow and orange flowers are congenial mates for brown or bronze foliage.
Some of the best plant combinations (in my garden, anyway) are accidental. Right now we are enjoying some jolly cherry-coloured opium poppies that sprang up next to the elongated, carmine stems of the ruby chard that has gone to seed. And in the spring, nature arranged for some self-seeded Spanish bluebells to knit themselves through a group of the pinky-orange-cupped daffodil, 'Mistify'.
It's hard to do better than the hand of nature - which is why we gardeners are always able to learn from her.
jpowers@irish-times.ie
Further reading: Designing with Plants, by Piet Oudolf with Noel Kingsbury (Conran Octopus, £25): first published in 1999, but still relevant. The RHS Encyclopedia of Planting Combinations by Tony Lord and Andrew Lawson, revised and expanded edition (Mitchell Beazley, £30)