As summer arrives, salvias begin to shine bright. Gently trembling with the attention of bees, it’s hard not to notice their brilliant colourful flowers that often continue for months at a time.
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When summer tightens its grip and many herbaceous plants begin to flag, salvias continue to charm, appearing fresher than ever. While many are tender in cooler climates, there are those that are hardy and can take sub-zero temperatures, happy to return the following summer for another riot of colour.
There is a salvia for almost every style of planting scheme. They look great in a herbaceous border and also look great in a tropical or exotic planting scheme, pairing well with dahlias. Salvias cope well with wind, so are ideal for a coastal garden, and as many are drought tolerant, they are good plants for a dry garden. They also grow very well in pots.
With so many to choose from, picking one can seem a little daunting. Thankfully, the RHS has recently trialled a large selection of hardy salvias, selecting the best performers and giving them the Award of Garden Merit. “We had one of our wettest 16 months and it really pushed the plants in the trial,” says the trial chair, Cathy Rollinson. “Despite this, those awarded the AGM continued to perform well.” As we face ever more uncertain and extreme weather, we need plants like this that can perform well, and for a free-draining sunny spot, salvias are hard to beat.
Salvias - what are they?
Salvia is one of the largest genera in the mint and dead nettle family, Lamiaceae, containing more than 1,000 different species and now encompassing previously separate genera such as Russian sage (formerly Perovskia). It’s found across the world, with many ornamental types coming from central and south America, central Asia and the Mediterranean. This vast territory means that garden plants come in the form of annuals and biennials, herbaceous perennials and woody shrubs, all varying in degrees of hardiness.
Herbaceous perennial salvias such as Salvia nemorosa, Salvia verticillata, Salvia pratensis and Salvia x sylvestris are hardy and can withstand winter temperatures as low as -22°C. Although their flowering period is usually restricted to summer, they will repeat if deadheaded or sheared back.
Tender perennial salvias such as Salvia greggii and Salvia elegans are more tender or borderline hardy and may not get through a cold winter without protection.
Woody or shrubby salvias such as Salvia microphylla, Salvia greggii and Salvia x jamensis will take temperatures down to around -12°C and can be evergreen in mild winters.
Nearly all salvias dislike wet winter soil conditions that rot the roots and can kill even the hardy varieties; it is a good idea to take a few cuttings in late summer to increase your stock of plants and insure against any losses over winter.
When do salvias flower?
Salvias start to flower in early summer and can easily go on until the first frosts, if deadheaded to encourage more blooms. As a group, salvias have the ability to flower and look good during periods of intense heat and dry weather. They also have delicately shaped flowers, avoiding ostentatious double forms, giving them a naturalistic charm and making them a popular source of nectar. Increased interest in the past 30 to 40 years has led to lots of breeding, resulting in colours that range from pinks, whites and mauves, through to deep reds, electric blues and dark purples. There are even pale yellow, soft cream and apricot colours available with cultivars such as S. x jamensis ‘Lemon Light’ and S. ‘Apricot Spring’.
How to grow salvia
Where and when to plant salvias
• Salvias need an open sunny site with good airflow and excellent drainage to do their best year on year. Their biggest nemesis is winter wet. The best time to plant is in late spring after the danger of winter frosts has passed, allowing the maximum amount of growing time for plants to establish before winter.
The best soil for salvias
• The ideal soil should be free draining so avoid heavy clay soils and those that are regularly nourished with organic ingredients, such as home-made compost or rotted farm manure. Along with increased moisture content, organic rich soils can promote soft, lush growth that can be prone to flopping in the growing season and frost damage in winter.
When to cut back salvia
• Many of the herbaceous types can be sheared after their first flush of flowers. Trimming all growth back will encourage quick regrowth and more flowers.
• Deadhead woody salvias back to a lower pair of leaves. If they are reluctant to flower then a judicial trim and prune of neighbouring plants will help increase light and airflow, along with a high-potash feed that will induce flower bud formation. If exposed to strong winter winds, then a light trim in late autumn of woody plants can be beneficial in preventing wind rock, but avoid cutting them back hard.
• In winter, you can completely remove the dead foliage of soft herbaceous types, though leaving them through winter for a spring tidy will offer some protection.
For shrubby types, leave the year’s growth until the following spring before trimming back hard to the main framework, where fresh, new leaves are appearing.
Do slugs and other pests eat salvia?
• Salvias are relatively pest and disease free. Their aromatic oils tend to put off pests such as molluscs, rabbits and deer, and the sulphur within the oils acts as a natural fungicide against mildews and leaf blackspots.
Dividing salvia
Division is possible during the growing season after the first cut back, though the crown and roots of the plant will be quite woody and so can be slow to re-establish. It is always a good idea to propagate salvias, partly as an insurance against any winter losses, but also to rejuvenate or increase your display. Grow divisions on in containers in a loam-based compost to offer the best conditions for regrowth.
How to take salvia cuttings
Take a few cuttings in late summer to increase your stock of plants and insure against any losses over winter.
Select some non flowering shoots, around 8cm long and place immediately in a plastic bag to retain moisture
- Remove the lower leaves
- Place around the edge of a pot filled with gritty compost
- Water and cover with a plastic bag or put in a propagator
- Keep over winter in a frost free place
Salvia in brief
What Summer-flowering perennials and sub-shrubs that are hardy in the UK, and commonly known
as ornamental sages. A genus of more than 1,000 species, which also includes tender perennials, biennials and annuals, Salvia is classified within the Lamiaceae family.
Size Varies from around 50cm to 1.5m in height.
Season Flowers summer through to autumn.
Conditions Many of the species come from mountainous regions with dry, free-draining conditions, and require an open sunny site with free-draining soil.
Origins Salvias are found on nearly all continents, but those featured here are from across Europe and parts of Asia, with some species native to Central and South America including Mexico.
Hardiness These are species that are hardy throughout most of the UK with an RHS hardiness rating of RHS H4 to H7, and suitable for gardens in USDA zones 4a to 11.
Great salvias to grow in your garden
Salvia nemorosa ‘Amethyst’
A larger cultivar with elegant tall stems holding masses of warm, reddish-mauve flowers that contrast nicely with maroon calyces. Flowers repeat throughout summer. Height and spread: 1m x 70cm.
RHS H6, USDA 4a-8b†.
Salvia x digenea ‘Adrian’
A neat and compact plant forming a dome of aromatic grey-green foliage, complemented
by numerous spikes of white flowers through summer. 70cm x 80cm. RHS H6, USDA 5a-8b.
Salvia uliginosa
A tall and upright salvia with white and sky-blue flowers atop lofty, long stems from midsummer to autumn. Appreciates more moisture than other salvia species. 2.1m x 1.6m. RHS H6, USDA 6a-10b.
Salvia x sylvestris ‘Rose Marvel’
A compact form with tidy grey-green foliage and vibrant, rose-pink flowers that contrast beautifully with the purple-red calyces, giving a colourful display. 40cm x 50cm. RHS H7, USDA 4a-8b.
Salvia pratensis ‘Rose Rhapsody’
A compact form of clary sage with dense upright spikes of large, soft-pink flowers that start a deeper pink in bud from darker stems and calyces. 60cm x 50cm. RHS H7, USDA 4a-8b.
Salvia forskaehlei ‘Dale Farm Rose’
An elegant form of the indigo woodland sage with large basal leaves and slender stems, giving way to an airy display of lilac-pink and white flowers. 90cm x 70cm. RHS H5, USDA 5a-11.
Salvia ‘Endless Love’
Mounds of aromatic soft green with relaxed stems of densely packed violet-purple flowers from midsummer to autumn, with stems and bracts continuing to offer colour. 60cm x 90cm. RHS H6, USDA 5a-8b.
Salvia nemorosa Caradonna Pink Inspiration (= ‘Tucarink’)
Soft green foliage and long flower spikes give this salvia an elegant look. Blush-pink flowers contrast with dark-burgundy calyces. 80cm x 80cm. RHS H6, USDA 4a-8b.
Salvia x digenea ‘Merleau Rose’
A compact perennial with mid-green foliage and dark, elegant stems. Dark-red calyces give rise to contrasting pale-pink flowers from summer to autumn. 60cm x 70cm. RHS H7, USDA 5a-8b.
Salvia pratensis ‘Indigo’
Large, purplish-blue flowers contrast beautifully with the burnished-green calyces. Will repeat flower from summer into autumn after a thorough deadheading. 1m x 90cm. RHS H6, USDA 4a-8b.
Salvia x sylvestris ‘Mainacht’
A compact perennial with dark-green foliage and densely packed flower stems of deep-violet flowers in early summer. Will repeat if cut back. 60cm x 70cm. RHS H6, USDA 4a-8b.
Salvia nemorosa ‘Lubecca’
A dependable cultivar with soft, fresh-green foliage. From early summer, graceful upright racemes appear full of violet-mauve flowers, continuing through to early autumn. 70cm x 80cm. RHS H6, USDA 4a-8b.
Salvia x sylvestris ‘Blue by You’
A floriferous cultivar with dark-green foliage that complements rich purple-blue flowers and dark- reddish bracts. Quick to regrow after a midsummer shear. 70cm x 60cm. RHS H6, USDA 4a-8b.
Salvia nemorosa ‘Caradonna’
A well-branched plant with upright habit and dark-green foliage. Lovely dark flower stems hold and contrast the violet-purple flowers elegantly spaced along each stem. 80cm x 70cm. RHS H6, USDA 4a-8b.
Salvia verticillata ‘Hannay’s Blue’
A tidy, soft growth habit with bright-green leaves that emerge tinged with reddish tones. Flowering through to autumn with whorls of soft-blue flowers that contrast with the dark calyces. 80cm x 70cm. RHS H6, USDA 5a-8b.
Tender salvias
Salvia 'Amistad'
A spectacular tender perennial with aromatic foliage and masses of royal-purple flowers that have almost-black calyces. It starts flowering at the end of June and will continue up until October. 1.2m. AGM. RHS H3, USDA 8a-11.
Salvia discolor
A straggly plant with aromatic silvery foliage, slightly stick-like stems and almost-black flowers. A tender perennial that needs mollycoddling over winter. The crushed foliage smells of blackcurrant. 50cm. RHS H2.
Salvia leucantha 'Purple Velvet'
Salvia leucantha is a vigorous, tender salvia, rather late-blooming. It makes a mound of long, felted, grey leaves, usually nearly a metre high and wide by September when the flowers begin to emerge. In October it is a fountain of purple. The flowers are actually white, but the calyxes and the whole flowering stem are covered in furry purple velvet, making the long arching flower stem look like scrunched up purple and white chenille, totally surreal. ‘Purple Velvet’ is all purple, less shocking but easier to use in the garden. 1m.
Salvia confertiflora
Giant pots of this, threaded informally between specimen Agapanthus praecox creates an exuberant floral display which lasts into October. It may not be winter hardy, but the rate and quality of growth in a single season merits better recognition for summer display. Stems are covered in a rash of scarlet hairs that define the elegant profile and each carry a succession of coral-red flowers in ascending whorls. Even when flower petals drop, the dark red calyces will command admiring glances. Cuttings taken at the end of summer can be over-wintered for next year. 150cm.
Salvia greggii ‘Icing Sugar’
All the Salvia gregii cultivars flower over a long period. Although there is never a mass of flowers they continue throughout summer. Dozens of new forms are being introduced at the moment. I like this one for the complementary colours of its dark pink and pale pink flowers. Lots of claims are made about the hardiness of this plant but given they have not survived the past two winters, take cuttings at the end of the summer, or treat them as an annual and buy new plants each year. 50cm.
Salvia ‘Phyllis’ Fancy’
Although many salvias come into flower earlier than ‘Phyllis’ Fancy’, none have a nicer colour in late autumn. The colour seems to deepen as temperatures fall. The lavender-blue flowers, which have a whitish lip, are set off by inky-blue brachts. If you plant your overwintered pot in the open ground in spring, you will have a gorgeous clump come autumn laden with flowers. This can mean that it’s difficult to find a shoot without flowers for taking autumn cuttings, but with some luck the original plant will survive if the winter is not too cold.
Salvia concolor
A massive plant with deep royal-blue flowers on flower spikes that can be 50cm long. Borderline hardy. 2.5m. RHS H4, USDA 8a-10b.
The history of salvias
Our love affair with these hardy salvias can be traced back to Roman times, when the culinary species S. officinalis and S. rosmarinus (rosemary) were used as medicinal herbs, so it comes as no surprise that Salvia derives from the Latin salvus, meaning safe. The aromatic oils given off by many species make them a pleasure to brush past in the garden, but these are also considered a natural fungicide, which is why salvias are often planted alongside roses to alleviate mildew and blackspot.
Where to see and buy
• Dyson’s Nurseries Comp Lane, St Mary’s Platt, Sevenoak, Kent TN15 8QS. Tel 07887 997663, dysonsalvias.com
• Westons Salvias The Coach House, Henllan, Llandysul, Ceredigion SA44 5TX. Open by appointment. westonssalvias.co.uk
• Read more about the RHS trials at rhs.org.uk/plants/trials-awards
