These stalwart perennials will provide flowers to summer's end.
Salvias are a diverse group of herbaceous and shrubby perennials, with various species and varieties flowering from summer through to the first frost. Those species flowering later in the season are perhaps the most diverse group of all, with everything from foot high shrublets to towering eight-foot giant perennials. Many come from the warmer drier climes of southern USA, Mexico and South America, rendering them a little vulnerable in the winter-hardiness stakes, but they are so endearing and of such value in terms of delivering late colour they are always worth the risk.
The shrubbier kinds are largely derived from S. greggii, S. microphylla and the hybrid between them S. jamensis. They are of rounded habit, producing thin shoots, with neat aromatic leaves and a succession of small large-lipped flowers in shades of blue, red, white, pink and purple. Many of the taller forms are derived from the anise-scented or hummingbird sage S. guaranitica from South America. It’s a leafy, upright, highly aromatic perennial producing 1.5m (5ft) stems topped with slender spikes of blue or purple flowers with black calyces. Being weak jointed it may need additional support, but once happy will produce stout clumps. Warmer winters is encouraging more of the later and more tender types to be tried in cultivation. One of the prime movers is William Dyson who also runs Great Comp Garden, near Sevenoaks, Kent. His website profiles and illustrates a wide range of varieties and is well worth looking at, and although there is no mail order, the nursery and garden also demands a visit (www.dysonsalvias.com).
While the larger forms are best grown in a warm, sheltered border, those achieving around 3ft or less are ideal for pots. Use John Innes No 2, with additional grit or Perlite added for drainage, particularly if you plan to keep the plants for more than a season. Plants grown commercially tend to be grown in peat or peat-free composts, encouraging fast growth, but risking becoming soggy in winter.
Salvias prefer full sun, and moist, but well-drained soil, particularly if they are to survive the winter. Well-drained sandy or chalky soil is ideal, while heavier, clay soil needs grit to improve drainage. Avoid rich soil or overdosing with fertiliser as this may cause lush, brittle growth prone to winter rot. It’s best to treat them on the mean side!
Salvias are best propagated from cuttings. The taller types take softwood or basal cuttings of new growth in spring, while the shrubbier kinds take soft wood or semi-ripe cuttings in summer or autumn.