Shrubby salvias’ colourful blooms amid scented foliage
In the brilliance of the garden, as summer heads towards its peak, one group of flowers sparkles with an intensity that sets its blooms apart. These are shrubby salvias, tidy little bushes lavishly embellished with a myriad of tiny, gem-like flowers in shades of amethyst, garnet, topaz or opal. Starting early in the season, the flowers shine radiantly through summer hazes and autumn mists until subdued by a dusting of frost. Originating largely from Mexico and the southernmost states of North America, today’s shrubby salvias fuse the untamed beauty of a wild flower with the skill of modern breeders, who are producing hybrids in a tremendous range of colours and appearance. Forming leafy bushes, ranging from knee-high to just over 3ft (1m), these perennials and shrubs not only make an invaluable addition to herbaceous borders and prairie planting, but also form a colourful display when mass planted. Singly, they can be grown in containers or dotted about gravel beds: alternatively, planted in a line, they add an attractive informal edging to a path. But above all, they are easy to grow, provided the soil is very well-drained, and the position is sunny. The salvia family covers a staggering 900 different species, including edible sage, Salvia officinalis. Sage was used as a healing plant by the Romans and Greeks, and the name salvia derives from the Latin salveo, meaning ‘I heal’. Among the most popular garden plants are a group of shrubby salvias that are endemic to Mexico and the USA. The species include the lesser-known Salvia chamaedryoides, Salvia lycioides and Salvia muelleri. However, the species most commonly grown in the
UK are Salvia microphylla, Salvia greggii and a cross between the two, Salvia x jamensis, which is a hybrid that occurred naturally in the wild. In the early 1990s, it was discovered growing in a valley outside the Mexican village of Jame: both its parent species were growing nearby.
Long flowering season
It is predominantly from the S. greggii, S. microphylla and S. x jamensis species that specialist William Dyson breeds the captivating new cultivars for which his nursery, Dyson’s, is well-known. “I love growing salvias, and there are few other plants that flower almost non-stop from May until November. You can even find some flowering on Christmas day,” he enthuses. William is also curator of Great Comp Garden in Kent, where he has established dozens of cultivars. “Once I discovered shrubby salvias, I became hooked, and since then, I’ve sought out as many forms as possible.” His love affair with salvias was ignited in the early 1990s, after plant hunters James Compton, John d’Arcy and Martin Rix returned from Mexico with many exciting, hitherto unknown cultivars. “I acquired some seeds and planted them in dry, free-draining greensand, a soil supplement rich in minerals, where, to my surprise, they not only flourished,
PRUNING SHRUBBY SALVIAS
Pruning, William stresses, is one of the most important aspects of cultivating shrubby salvias. “Pruning twice annually promotes an attractive bushy growth habit,” he says. He recommends pruning fairly hard in late March or early April, removing dead wood and cutting back as low as possible without damaging the emerging growth. Cutting into bare wood should be avoided, for fear of damaging the plant. A second pruning is recommended in early July, dubbed the ‘Hampton Hack’ because it coincides with the Hampton Court Flower Show. “Not only does this encourage a tidy framework of branches, it also removes the spent flowers from the early flush of flowering, fostering another major flush,” he says. Thereafter, with regular deadheading, plants continue flowering all season without becoming straggly. Come autumn, only plants that are being overwintered in a glasshouse need pruning.
but happily survived our winters,” he says. “Had they keeled over and died, it might have been a quite different story.” While won over by the showy flowers, he was delighted by their tolerance to dry conditions. “With climate change, we are seeing increasingly dry summers, so drought-tolerant species are becoming very popular,” he points out. The majority of shrubby salvias are hardy, thriving in sunny sites and well-drained soil, but they will not survive cold, wet winters in waterlogged ground. The hardiest is S. microphylla, more so than S. greggii, while S. x jamensis is in the middle. “And once they are established, they need no water other than what may or may not fall out of the sky,” adds William. Nor do they demand very much care, apart from light pruning in spring and summer, and a regular trimming of spent flower spikes. Shrubby salvias are nectar-rich, and the brightly coloured flowers are prized by pollinating insects. The flowers are arranged on stiff stalks, either in opposite pairs or whorled. They open in turn, starting from the lowest and progressing over time to the tip of the spike. The stalks may also be coloured, either pink, purple or near-black, co-ordinating with the calyx. Each flower is held in the calyx, a cup-type structure into which the throat-like corolla of a flower slots. In some cultivars, the calyx is also coloured, adding interest long after the flowers have fallen to the ground. The flower is made up of an upper lip, which is often hairy and located directly above a lower lip, consisting of four rounded lobes. Deep within the corolla is a forked stigma and anthers coated in pollen, a magnet to bees. Some flowers are a single rich colour or softly flushed, such as Salvia microphylla ‘Heatwave Glimmer’, which bears white flowers with the faintest blush. Others are bicoloured: Salvia ‘Dyson’s Joy’ has pretty two-tone pink flowers in great abundance, while Salvia ‘Crazy Dolls’ is magenta above soft pink. The buds, too, can be richly-hued. Salvia ‘Javier’ bears innumerable velvety, purplish-black buds that open to display purple flowers, a contrast to the lime-green leaves.
Fragranced leaves
The leaves on shrubby salvias are small and abundant, arranged in pairs up each woody stem and measuring ¾-1½in (2-4cm) in length, depending on the cultivar. They come in countless green hues; light to dark or bright to dull, the surface matt or polished. The outlines of the leaves vary from egg-shaped, or elliptic, to linear or loosely oblong. Being so small, the leaves do not stand out texturally, but closer inspection reveals that some are leathery, others softly hairy or sleek. The edges can be smooth or toothed. In some cultivars, the serrations are rounded, in others more jagged.
Maybe the greatest feature of the leaves, though, is their aroma. “If a shrubby salvia is not flowering, I can tell its cultivar purely from the smell of the leaves,” says William. He compares the fragrance of Salvia ‘Dyson’s Orangy Pink’ with potpourri, while the foliage on Salvia ‘Nachtvlinder’ smells of blackcurrants. Studying the surface of a salvia leaf through a magnifying glass reveals tiny glandular hairs that hold globules of oil. There is a misconception that shrubby salvias are not hardy, which derives from confusing them with tender cultivars that require overwintering in a glasshouse. “I have grown shrubby salvias for 23 years in west Kent, in temperatures as low as -11°C, and winter survival has generally been very good. The exceptions have been due to mild, wet autumns followed by long, cold winters,” he points out. He has encountered some gardeners in the Midlands who have overwintered Salvia microphylla cultivars at temperatures below -15°C.
Mountain habitats
This should come as no surprise because many are bred from plants that grow high in the mountains and, originating from high altitudes, must be hardy to survive. The lovely, glowing magenta Salvia microphylla ‘Cerro Potosi’ originates from a Mexican mountain of the same name. “This cultivar provides a benchmark in terms of ornamental value and hardiness,” he says. “In a severe winter, it may be knocked to the ground, only to pick itself up the following spring.” As a result of breeding since the early 1990s, recent cultivars have a more pleasing habit and an increased flower-to-foliage ratio. “The rate of new introductions is rising exponentially, and this is an exciting time for salvia breeders,” says William. He was recently involved in a Royal Horticultural Society (RHS) trial of some 80 cultivars originating from Mexico. As a result, the best-performing cultivars were granted an Award of Garden Merit (AGM). Among them is ‘Cerro Potosi’ and ‘Dyson’s Joy’, a striking pink and purple bicolour bred eight years ago at the nursery. It is a hybrid between a pink Salvia x jamensis and a small, unidentified shrubby Mexican species. “It has inherited the delicate twiggy habit of the latter, but is considerably more floriferous than either parent,” he says. If frequently deadheaded, it blooms copiously in a sheltered sunny spot and, being just 2ft (60cm) tall, thrives in containers. He has named some new cultivars after members of his family. Salvia forreri ‘Karen Dyson’, with its soft pink petals and white throat, is named after his wife. However, the clue is in the name with other recent cultivars, such as ‘Dyson’s Maroon’ and ‘Dyson’s Crimson’. And currently in development is Salvia ‘So Cool Pale Blue’. “The flowers are a superb shade and they are very plentiful, but it is also very compact and hardy.” Another hardy form is Salvia ‘Hot Lips’, an AGM winner which bears masses of flowers in proportions of red and white colours that shift randomly through the growing season. “Gardeners tend to either love or loathe the gaudy red and white flowers,” says William. “I find it difficult to place, other
than in a container, or with dark blue flowers.” Less controversial is the vigorous Salvia ‘Jezebel’, which bears an unbroken stream of cherry-red flowers with black calyces. Another striking recent cultivar is Salvia ‘Nachtvlinder’, with deep purplish maroon flowers. “To fully appreciate the depth of colour, it needs to be grown alongside paler cultivars,” says William. Salvias are wonderful for adding continuous flower colour from midsummer, well into autumn. Compact cultivars suit the front of borders, in co-ordinated or contrasting colours or teamed with low-growing grasses to act as a foil to the bright colours. Taller cultivars can be dotted between dahlias, rudbeckias and fuchsias of a similar height, set against a backdrop of lanky heleniums, cannas and clumps of feather reed grass. In areas with harsh winters, it is advisable to plant shrubby salvias in spring, in order to provide a long growing season, allowing them to get well established. They are tolerant of a range of soils, from slightly alkaline through neutral to acidic, providing they are well drained. They should not be over-fed because it causes sappy new growth that is easily damaged by heavy
rain and wind. The necessity of good drainage and sunshine cannot be stressed enough. “They grow in low light levels and partial shade, but tend to flower less prolifically and lean towards the light, adopting an ungainly shape,” says William. Another vital consideration is ample air movement. “It is important in winter in order to avoid grey mould, which can be more devastating than a hard winter,” he notes. Grey mould, Botrytis cinerea, is best countered with good horticultural practices, promptly removing spent and fallen flowers before they become infected. Propagating shrubby salvias is easily achieved through softwood tip cuttings taken from the new growth generated in either the April or July prune. It is possible to take semi-ripe cuttings later on, but although they root successfully, the young plants may not have sufficient strength to survive the winter. Many cultivars produce tiny seedheads in place of the calyces, but resulting plants will not necessarily reflect their parentage. Any effort is worth it, however, when the tiny flowers emerge, sprinkling their jewels through the borders and enhancing the glorious colour of the summer garden.