Spiritually elevating effects of cool colours
The calming and spiritually elevating effects of cool plant colours such as blue, purple, lavender, violet and mauve are cumulative. Plant one purple salvia and it's a restful point of interest. But fill a glade with blue poppies, as did Elsie Reford in her Quebec garden masterpiece, Les Jardins de Métis, and it's a transformative event. In 1946, Reford sent a picture of her poppy glade along with her written thanks to British plant explorer Francis Kingdon Ward (1885–1958), who had brought the Himalayan blue poppy back from Tibet and made its seeds available through the Royal Botanic Gardens, Kew. She expressed her satisfaction with the poppies that had successfully adapted in Grand Métis, saying, “So well does [the flower] grow that to walk along a path between gently sloping banks entirely veiled with the exquisite blue poppiesis like going through some ethereal valley in a land of dreams.”
Initially, the blue border plan of British garden stylist Gertrude Jekyll had gained Reford's admiration and sparked her interest. Miss Jekyll's cool border combined intense blues and purples with grey, foam white, and pale yellow; but her blue poppies failed to excel in the British climate and couldn't hold a candle to Reford's.
The cool palette is the broadest group of hues, tints and shades to be found in petals and foliage. Few cool colours are pure hues, although one exception is the intense blue of several gentian species, including two easy-to-grow types, the summer and the willow, both admired for their flared, late-summer, true-blue flowers. While some gentians are subtle hues of white or yellow, the deeply saturated colour of the blue species has sufficient impact to jolt a border—their intensity can overwhelm a planting scheme. Cool colours with complex shades and suffusions are more adaptable in mixed plantings. Blue and purple are often imbued with red to produce violet, mauve and lavender. I once nurtured a solitary specimen of Himalayan blue poppy grown from seed and can report that it was a washed out blue flushed with pinkish mauve (of which a treasured photograph exists). Others I've seen certainly had a better blue colour, but mine had been influenced by soil and climate conditions, and perhaps the unpredictability of seedling variation. Similar red flushing also appears in the flower buds of Virginia bluebells and in the tiny blossoms of ephemeral woodland forget-me-nots, both of which are medium sky blue suffused with purple and pink. The large family of perennial geraniums includes many blue and purple flowers strongly influenced by red pigment to producea range of cool colours, such as ‘Purple Pillow' (magenta-purple), Geranium himalayense (violet-blue with a reddish pink cast) and ‘Nimbus' (amethyst purple flushed with pink).
When planting in cool colours, we need to anticipate and employ the visual trickery of deep hues. The darker the colour, the more it will optically recede, suggesting the planting space is deeper and larger than it actually is. This is an excellent trick to employ in small gardens. A stand of deep violet-blue ‘Bressingham Spire' monkshood will give a corner more depth, but used alone, cool colours in the dark range can appear muddy. They can be improved with just a touch of a paler and less concentrated accent plant colour to lighten the image and bring it forward. Good plant partners with the monkshood include smoky lavender ‘Purple Sails' coral bells and a ruffled clump of ‘Golden Tiara' hosta, with light green, heart-shaped leaves edged in chartreuse and purple flowers in July. A similar dark-and-light partnership can also be struck among deep purple ‘Prairie Dusk' penstemon combined with the lavender-blue flowers and silver-grey leaves of ‘Little Spire' dwarf Russian sage and a bright clump of ‘Moonshine' yarrow, with its canary yellow flowers and grey-green leaves.