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Home & garden.

16 August 2021

How to grow salvias

Salvias come in a wide range of colours and look beautiful in summer. Discover our best varieties and tips for how to grow them.
CT
Ceri Thomas
Salvias

Salvias are one of those amazingly diverse groups that make you wonder how such variety can exist among plants of the same name. From hardy herbaceous perennials to tender bedding plants, the herb sage and vibrant shrubs, their unifying feature is brightly coloured, nectar-rich flowers, which bees love.

Which? Gardening magazine grew a range of popular varieties, both hardy and tender types, to see which would give us the best display and be hardy enough to get through UK winters.


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Key facts

PLANT TYPE Herbaceous perennial

POSITION Full sun

SOIL Well-drained, not too fertile

How to grow salvias: month by month

January
February
March
April
May
June


CUT BACK HARDY TYPES
PLANT
PLANT/CUT BACK TENDER TYPES/FLOWERING
FLOWERING
July
August
September
October
November
December
FLOWERING
FLOWERING
FLOWERING
FLOWERING


Best salvia varieties

Which members can log in now to see the full results and which are our Best Buy varieties. If you're not a member, join Which? to get instant access.

Best Buy tender salvias
What it looks like
Variety name
Height x spread
75 x 80cm
This variety brought all the best aspects of tender salvias together in one very long-flowering package. Strong, leafy stems were completely self-supporting and had plenty of long, scarlet, tubular blooms with the characteristic hooded mouths. We noticed that in very hot weather (over 30°C), the stems and blooms of this and a few other varieties drooped, but they perked up again when the weather cooled down and were still flowering beautifully in October. Unfortunately, none of the plants survived the winter. Peak flowering: Jun-Oct
What it looks like
Variety name
Height x spread
130 x 60cm
Once these got into their stride in July, the deep magenta flowers really stood out, and not just because they were head and shoulders above most of their neighbours. The short, hooded flowers were showy, and there were plenty of them. The long stems were stiff, slightly brittle and needed some support, but that was easy to put in place. They flowered well into autumn and came through winter successfully. Peak flowering: Jul-Oct
What it looks like
Variety name
Height x spread
170 x 65cm
A definite ‘back-of-the-border’ plant due to its size, this salvia was very popular with bees and provided plenty of late flowers to keep them happy. Those small but plentiful sky-blue blooms were quite different from the many hot colours we had in the trial and continued to flower, even after the first frosts. Long stems had a free-spirited, spiralling shape that was a joy to behold, although they needed some support to stop them flopping. All plants survived winter. Peak flowering: Aug-Oct
What it looks like
Variety name
Height x spread
60 x 40cm
Probably one of the most well-known of the tender salvias, and hardy in our trial, this variety came up trumps with a winning display of vivid, crimson flowers. The black stems and deep-purple calyces at the base of the flowers seemed designed to show the flowers off so they caught the eye, even if at times there wasn’t a huge mass of bloom. The dense, bushy shrubs had tiny, delicate leaves on wiry stems.  Peak flowering: Aug-Oct
What it looks like
Variety name
Height x spread
80 x 35cm
We sowed the seeds in late March, planted in early June, and they were in flower by August. With a bit of deadheading they carried on flowering into autumn. Planted in a small group, they had great impact, and we loved the deep, royal-blue flower colour and their straight, upright shape. Peak flowering: Aug-Oct

Best Buy hardy salvias
What it looks like
Variety name
Height x spread
80 x 80cm
The sheer mass of slender flower spikes these plants produced resulted in a sea of vibrant colour that lasted for months. New spikes constantly replaced the old, and such bushy, branching growth meant they kept their shape well. The dark green leaves were pleasantly scented when handled. Flowers were easily deadheaded by snipping off the spikes as the colour faded and were very popular with bees, which constantly buzzed around. Peak flowering: Jun-Sep
What it looks like
Variety name
Height x spread
65 x 90cm
A Best Buy for the second time, this salvia was short and squat, but no less lovely for it. Plants formed low, rounded bushes that were densely covered in short flower spikes. The intense lavender-blue of the tufty flowers looked vibrant in sun and on dull days, and they were popular with bees and hoverflies. They looked showy and colourful at the height of summer and beyond, lasting particularly well in north London. Peak flowering: May-Aug
What it looks like
Variety name
Height x spread
170 x 65cm
We had to agree with the many visitors to the north London trial garden who thought this was a particularly good salvia. Tall and slender, the neat clumps would suit a small garden, but had great impact thanks to their vibrantly coloured flowers. While the first flush of flowers was the fullest and brightest, new spikes kept growing, so plants still had plenty of colour until the end of the summer. Peak flowering: May-Jun
What it looks like
Variety name
Height x spread
75 x 50cm
A Best Buy in our last trial and a worthy winner again, this salvia was first bred just after WWII. The constantly branching stems helped to make this one of the longest flowering varieties at both trial sites. In north London, it also proved to be the most popular with bees. Stems flopped outwards by mid-summer, but new growth soon filled the gap and took over flowering as the outer flowers faded and were cut back  Peak flowering: May-Sep
What it looks like
Variety name
Height x spread
55 x 90cm
White flowers are unusual among salvias, so we were delighted to find that this salvia had the energy and showiness to make it one of the best varieties in the trial. The quantity of flowers produced was hard to beat, the bees loved it and the leaves were fantastically aromatic. When the massive first flush of flowers faded, we took off the flowerheads with shears and were rewarded with another, smaller flush later on. Peak flowering: Jun-Aug
What it looks like
Variety name
Height x spread
80 x 70cm
A lovely shape and standout colour made this another popular variety. The slim stems held flowers along most of their length. They were one of the first to flower and new stems grew through the older ones as the summer progressed, to keep the display going. It did particularly well at our trial gardens in north London, and had a slightly shorter flowering season in Scotland, where it proved the most popular variety by far with bees.  Peak flowering: May-Jun

How we test tender salvias

We grew 24 varieties of tender, half-hardy and borderline-hardy salvias. Many were supplied as plug plants, which we grew on to a larger size before planting out. We planted three of each variety at our Capel Manor trial garden in north London in early summer. Here, the soil is very well-drained and in full sun, although the bed we used has some shelter from a nearby hedge. We kept the salvias well watered until they were established, and then only watered them during very hot, dry weather. We put supports in place only if the plants started to flop. We assessed them until the first frosts hit in early November, and then left them in the ground over winter so we could see which would survive and regrow the following spring.

How we test hardy salvias

We planted three of each variety at our Capel Manor Gardens trial site in north London, where the soil is well-drained and the climate is mild, and three at Logan Botanic Garden in Dumfries and Galloway, where the soil is heavier and the climate cool and often wet. Plants were assessed regularly for impact and duration of flowering;  whether leaves were aromatic; attraction for pollinating insects; and whether they survived the winter. Records were kept for both years, but results irelate to the second year when plants were mature. All plants were deadheaded to see how well they re-flowered.

Caring for your plants

Planting tender salvias

If buying plug plants, pot them up into 9cm pots and grow them in a frost-free place until the roots reach the sides before planting out. Plant out into well-drained soil in a sunny spot. Avoid frost pockets and exposed, windy areas of the garden. Plant in late spring or early summer, after the danger of frosts has passed. Plants bought late in the season (August or September) would be best kept in a frost-free place over winter and planted the following year. If planting into containers, use a Best Buy compost for containers.

Planting hardy salvias

Planting in spring is best, so plants have time to establish fully before the winter. Plant in full sun or light shade. Salvias need good drainage, especially in winter, so plant in well-drained soil.

Propagating

Take cuttings in August or September to overwinter your plants indoors in a light, frost-free place. 

Caring for hardy salvias

There’s no need to feed plants grown in the ground as they thrive in poor soil. If growing in a pot, add a Best Buy controlled-release fertiliser at planting time. Regular deadheading can prolong the flowering period, but watch how your salvia grows. Some will re-flower freely from side shoots and only need to have dead heads snipped off, while others flower in flushes so can be trimmed back with shears when flowers fade. Late-summer flowers can be left on the plants over winter, and cut back when new shoots appear in spring.

Hardiness of tender salvias

All our plants were left unprotected in the ground over winter. We had several frosty spells in the first half of winter with temperatures down to -5°C, but it was otherwise mild and unusually dry. All the smaller, shrubby varieties were hardy – many were still in leaf at Christmas– as was S. uliginosa. None of the three ‘Wishes’ series or S. patens ‘Cambridge Blue’ survived. Shrubby varieties (S. microphylla and S. x jamensis) are often described as hardy, although always with the caveat that they need well-drained soil and sun.

If you aren’t sure your conditions are suitable, you could move your plants undercover in late autumn. If you want to leave them in the ground, either take cuttings in August to September and keep them frost-free overwinter, or protect your plants.

To protect them, cover them with fleece, mulching the crown or lifting the tubers of S. patens varieties. The shrubby varieties will probably lose their leaves and should be trimmed when they start to regrow in late spring or early summer. Long-stemmed salvias regrow from the base, so leave the top growth to die and then cut it back when regrowth starts and frosts have finished.

Common growing problems

Slugs and snails

Slugs and snails may eat young growth in spring so protect your plants with organic slug pellets or use biological-control nematodes (slugs only).

Read more about slugs and snails

Powdery mildew

Powdery mildew can be a problem, especially on very dry soil. A white fungal bloom appears on the surface of the leaf. Remove affected leaves, water plants if the soil is very dry and try to avoid too much overcrowding around the plants to allow the air to move freely.

Read more about powdery mildew