Purple is like the ideal party guest: it mixes perfectly with everyone in the room and yet still manages to look attractive and interesting when posing alone against a plain background. It is, I venture, incapable of upsetting anyone or anything.
So what a useful colour purple is in the garden. Given its make-up of blue and red, it works effortlessly with plants of all hues from that side of the colour-wheel. It also contrasts wonderfully well with orange, looks good with lemon, smart with white and cream and does sterling service with greens and silvers. I have been experimenting with using different tones of the same shade, planting purple Hesperis Matronalis and the perennial wallflower Erysimum Bowles Mauve together, and enjoying the play of light over similar flower shapes ranging from pale to dark. Coming up through the plants is a crimson Knautia macedonica which has a purple tinge to its colour and works happily with its neighbours. On a visit to Giverny in France, I learned that Monet originally planted small beds of plants made up of different varieties but all in the same shade so that he could study the effects of colour change as the wind moved through the flowers. Unfortunately these plantings have not survived but the garden remains sublime.
In plant terms you can indulge in the colour all year round. The Viola family will deliver purples from violets and pansies, not to mention the shades found in many crocuses and tulips in spring. I am enjoying swathes of Cerinthe major ‘Purpurascens’ with its bracts of purple and navy blue (full of bees right now) and irresistible irises in every shade of royal velvet, some streaked with white and others deeply sulky. Later in the year come the rich tones of Agastache, Penstemon and Hemerocallis and as autumn temperatures fall, the leaves of Vitis coignetia turn the most stunning shades. In foliage terms there are the Cercis Canadensis ‘Forest Pansy’, the Smoke Bush Cotinus Coggygria ‘Royal Purple’ and Sambucus Niger with its plates of frothy pink flowers.The stems of Salvia nemorosa Caradonna also take some beating, but the sweet box Sarcococca Hookeriana var. Digyna ‘Purple Stem’ and Cornus alba Kesselringii take my prizes for winter impact (though the little Japanese fern Athyrium niponicum ‘Burgundy Lace’ with its silver infusions is a plant any gardener would be happy to have).
Sometimes a little care has to be taken with placing deep purple flowers or foliage in very bright light – there is the risk that when backlit they might appear like black holes and lose their dignity or look a little dusty.
As a garden designer, I love those plants with the richest shades of purple. I’m underwhelmed by the pale mauves of most hostas and cannot get excited by bland lilac sweet peas. Give me the richest brocade of Tulip ‘Greuze’, the satin of Delphinium ‘Black Knight’ and the silk of Clematis Jackmanii and I will be blissfully happy from dawn until sunset.