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Gardens Blog

My Favourite Plant… September

As the summer draws to a close and borders are full of flame reds, oranges, golds and yellows, fading roses and firework dahlias, a forgotten plant suddenly makes a surge under the study window at home. This baked south facing bed is filled with a number of roses, a white Japanese anemone with land-grabbing tendencies, some hardy geraniums and a Romneya coulteri with a wandering habit and which never appears in the same place two seasons running. At the back of this crowd, Salvia guaranitica ‘Black and Blue’ now sends up bright, softly hairy pairs of oval green leaves and long spikes, black in stem and bud and bright blue in flower.

Its very unexpectedness is like a gift – the blue and black are dramatic and the green has a freshness which is a rare find at this time of the gardening year. My clump does not grow over tall, no more than 60cm, probably reflecting the competition it endures from other plants and bulbs, but this is a good thing as otherwise it would probably have to be dug up and moved and I like it exactly where it is. The blue contrasts satisfactorily with the white of the anemone, there are some deep pink nerines not too far away and the silver grey Romneya foliage adds a further foil.

There are two other well-coloured cultivars: ‘Blue Enigma’ is well known for its rich blue racemes from August or even earlier and ‘Argentine Skies’ is suggested by Christopher Lloyd in his invaluable book Garden Flowers as “its pale blue colouring contrasts kindly with the grey foliage of Artemisia ‘Powis Castle'”. However, he goes on to note, “there is an unwelcome touch of mauve in it” – so that one can be written off as unworthy of consideration without further debate.

In terms of cultivation, this salvia prefers a position in full sun with moderately fertile, moist but well-drained soil if possible. Like many salvias it will not tolerate sitting in a puddle. It flowers from August to October and in exposed areas it will need a mulch to protect it over the winter with a little fertiliser in spring. Do not overfeed or it will turn leafy and floppy. Remove flower spikes as they start to fade to prolong the flowering period.

It partners well with both warm and cool colours which is a bonus and looks stunning with oranges and purples as well as pale foliage such as my Romneya.