Salvias are RHS Plants for Pollinators. This genus of plants includes annuals and perennials, both hardy and tender. They are defined by their unusual lever pollination mechanism and offer a wealth of colour late in the growing season, with their upright spikes of jewel-toned flowers.
Salvias mainly originate from the Mediterranean and the Americas, therefore they like light, free-draining soil and a sunny position.
The RHS divide them into 5 broad groups:
Bedding Salvias
These are readily available in garden centres in late spring. You can buy them in packs of small plants and plant them out after the risk of frost has passed. They will last well into the autumn, but you may need to buy new plants each year. Examples include Salvia splendens and Salvia farinacea.
To prevent these becoming tall and leggy, encourage bushiness by pinching out the shoot tips in spring and early summer. This will delay flowering slightly, but give you a much fuller plant long-term. Throughout summer, deadhead regularly to encourage more flowers.
Tender Salvias
These are a diverse group including shrubby Salvia leucantha (Mexican bush sage) and the well-known Salvia ‘Amistad’. They are great for providing fresh, vibrant colour in late summer and early autumn, but won’t normally survive the winter outdoors. You can overwinter them in a frost-free greenhouse.
When stronger growth appears in spring, prune plants back to a low framework of branches, cutting just above a healthy pair of shoots. Or, renovate the plant entirely by pruning all stems to ground level.
Annual and Biennial Salvias
Often with larger flowers than other types, these salvias produce densely packed spikes in bright red or shades of pink, purple and blue, including pastels. Some flowers combine two colours.
Boldly-coloured annual salvias are excellent for plugging gaps in summer borders or in large containers with other annuals. No pruning is needed, but deadheading regularly will encourage further flowers after the initial flush.
Salvia viridis (annual clary) makes a good cut flower. It's blue, white or pink blooms, with distinctive veined bracts, are borne on sturdy stems that have a long vase life and dry well.
Biennials can be taller and are useful for giving height to borders. They’re easily grown from seed in spring and will produce seeds that you can collect and sow for a display in future years. They only flower once, in their second year, so pruning and deadheading isn’t necessary.
Culinary Salvias
Sage (Salvia officinalis) and rosemary (Salvia rosmarinus) are grown as herbs for cooking. The leaves are aromatic to touch and tasty when used in stuffings and Mediterranean dishes. Both are readily available to buy as plants in garden centres and supermarkets. Sage flowers are particularly popular with bees. Purple-leaved forms of sage need the brightest spot to fully develop their colour. Plants are also more aromatic in full sun.
Sage needs little pruning, but can be cut back as growth begins in spring to keep the plants compact. Renovate plants that have become too large or bare at the base by pruning back hard into older wood.
Renovate rosemary in mid-spring by cutting all stems back by half. Old, very woody plants are better replaced. Cut back after flowering in early summer.
Long-lived border Salvias
Long-lived border salvias are either shrubs, like Salvia microphylla, or herbaceous perennials, like Salvia nemorosa. They’re upright plants with flower spikes that rise above mounds of foliage.
Flowering throughout summer and into autumn, these perennials provide pops of colour in sunny borders. Long-lived border salvias come back year after year, they are easy to grow and are a favourite of bees.
These perennial Salvias can be divided into three sub-groups, and pruned accordingly:
deciduous varieties. Once fresh growth is visible, cut stems to their lowest node, around 40cm from the ground. S. Yangii should be hard-pruned to a low framework, 5–10cm (2–4in) tall, in mid-spring (March/April), cutting just above where new shoots emerge from the base.
herbaceous varieties eg Salvia nemorosa and Salvia x sylvestris Cut off all of the previous year’s growth in April, and then when the flowers fade in mid-summer (July), cut them back to near ground level to encourage a second flush of foliage and flowers.
shrubby varieties eg. Salvia x jamensis and Salvia microphylla. In April, to keep the height, simply prune out any shoots that have died back or been damaged over winter. Alternatively, to encourage vigorous new growth, keep them compact and stop them becoming woody, cut back stems by a third to a half. If flowering stops in mid-summer (July), give an additional light trim, cutting just below the faded flowers, to encourage a further flush of blooms in late summer and autumn.
If you would like to grow some in your garden, Salvias recommended by Gardner’s World are:
Salvia 'Amistad' - a half-hardy perennial. It is long-flowering and particularly floriferous, with rich-purple flowers. It's often still blooming when first frosts arrive, and is a good food source for late-season pollinators. Height x Spread: 50cm x 1.2m
Salvia nemorosa 'Caradonna' - a hardy perennial with spires of electric blue flowers in July to early September. Deadhead to prolong flowering. H x S: 50cm x 50cm
Salvia x jamensis 'Hot Lips' - a striking, shrubby salvia with bi-coloured red and white flowers. It is a frost-hardy but may need some winter protection. Other 'lips' cultivars are also available, including 'Amethyst Lips' and 'Cherry Lips'. H x S: 60cm x 1m.
Salvia nemorosa 'Ostfriesland' - a hardy perennial which is extremely popular with pollinators. It bears tall spikes of purple flowers from June to September. H x S: 45cm x 60cm
Salvia patens - vivid blue blooms which contrast beautifully with the deep green foliage. It is hardy in mild parts of the UK; in colder areas, mulch or lift the tubers, as with dahlias. Watch out for slugs, which enjoy the young shoots. H x S: 75cm x 50cm
Salvia microphylla 'Cerro Potosi' - a hardy, evergreen shrub with aromatic leaves and striking neon-pink flowers from midsummer to late autumn. H x S: 90cm x 75cm.
Salvia x sylvestris 'Viola Klose' - a stunning hardy salvia with radiant violet flower spires. It is an excellent alternative to lavender, flowering over a long period. H x S: 50cm x 50cm
Salvia 'Love and Wishes' - a generous flowering period, usually from June to November. Its rich pink-purple flowers, deep burgundy stems and a tidy growth habit make this a great choice for containers. H x S: 80cm x 50cm
Salvia uliginosa (bog sage) - As its name suggests, this sage prefers a moist (but not waterlogged) soil. This tall plant has clear blue flowers and is a good option for the back of a border. H x S: 2m x 90cm
Salvia x jamensis 'Nachtvlinder' - Velvety, purple-hooded flowers in summer and autumn. This tender perennial is frost hardy but may need some winter protection. H x S: 75cmm x 50cm
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