Horticulture Magazine

10 Dazzling Blue Flowering Shrubs & Bushes

ladybird sat on blue ceanothus blossoms

Shrubs and bushes are essential for adding body and depth to your garden, while choosing ones with blue blossoms brings a splash of colour to boot.

What is it about blue flowers that make them such a striking sight?

Perhaps it’s their relative rarity in comparison to white, yellow, red and purple blossoms; maybe it’s the cool tranquillity they lend to their surroundings.

blue flowering hydrangea growing either side of temple steps

Whatever the reason, blue blooms are quite something to behold and when adorning a bush or shrub, they can bring even more variety to your existing display.

Even though blue flowers are less commonplace can some other colours, there are still plenty of shrubs and bushes bearing their picturesque petals to choose from.

Here are ten of our favourite blue flowering specimens to provide some inspiration the next time you’re planning a makeover or tweaking the colour scheme of your garden arrangements.

1) African Lily

butterfly resting on agapanthus flowers

Despite originally hailing from South Africa, the African Lily (sometimes known as Lily of the Nile) has been bred to thrive in climes less kindly than its native land.

Today, the genus positively thrives in Britain, producing clusters of bell-shaped flowers on towering stems that can surpass 1.2 metres.

They bloom all summer long and add a striking blue focal point to any bed or border.

Thankfully, Agapanthus come in three different categories, according to their size: small shrubs, reaching a maximum of 60cm; medium-sized specimens, which can grow to around 90cm; or the larger varieties mentioned above, which exceed one metre.

a bee harvesting pollen from the white and blue flowers of an agapanthus plant

As such, you can choose whichever species fits best for the location in which you wish to plant it.

As for growing them, African Lilies perform best when drenched in sunshine, so plant them in a south-facing spot of the garden.

They’ll do well in any fertile soil that drains freely, though more vulnerable strains (A. africanus) may need transplanting indoors during the colder months.

2) Bluebeard ‘Heavenly Blue’

bee sat on flowering bluebeard plant
  • BOTANICAL NAME: Caryopteris x clandonensis

Also known as Heavenly Blue, this deciduous shrub will treat you to a spectacular display of dark blue flowers each August and September.

The blooms are stacked intermittently on spindly stems, atop a mass of pale green leaves with pointed tips and aromatic foliage.

Come winter, the plant will lose all of its finery and wither back into itself, before springing forth with new shoots the next year.

Best of all, Bluebeard is an absolute magnet for bees, butterflies and other pollinating insects.

magnified view of blue Caryopteris x clandonensis flowers with a bumblebee

That makes it an invaluable tool for injecting a dollop of biodiversity into your garden and ensuring it is full of life, colour and activity.

It makes a particularly pleasing addition to a mixed border or in amongst a collection of other shrubs.

The cultivar generally does well in most climates, being a fully hardy shrub that’ll stand up to even the most dramatic drops in the mercury.

If you do expect temperatures to plummet below 15°C, accommodate it by planting against a south-facing wall or fence, and prune and mulch each spring to ensure best results.

3) Buddleja ‘Blue Chip’

blue buddleja bushes
  • BOTANICAL NAME: Buddleja davidii

Speaking of butterflies, Buddleja aren’t known colloquially as “butterfly bushes” for nothing.

This particular cultivar, smaller and more compact than its more sprawling cousins, makes for a perfect border plant or can even be cultivated as a low hedge, giving off an intoxicating fragrance and drawing in countless fluttering wings to please both the sight and the smell.

Aside from the wonders that it will work for the diversity of your garden’s ecosystem, Blue Chip will also, as the name suggests, bring striking azure tones to your garden.

red admiral butterfly sat on the long flowers of buddleja davidii

The delicately bobbing stems will be awash with thousands of blue flowerheads throughout the whole summer long, making it highly useful as a cut flower, too.

A miniature deciduous shrub, Blue Chip isn’t likely to surpass 30cm in height, but could double that in width.

It loves the full warmth of the sun’s rays and will do well in almost all soil types, while it’s also resistant to drought, pests and disease.

Remove spent flowerheads to maximise blossoms and minimise self-seeding, but avoid pruning until the spring.

4) Blue Flowering Lilac

Syringa Vulgaris in bloom
  • BOTANICAL NAME: Syringa vulgaris ‘Nadezhda’

This Russian hybrid is a particularly striking type of lilac that can be grown as either a deciduous shrub or small tree.

Its heart-shaped flowers deliver up stems studded with pinky-purple buds, which unfurl themselves in late spring and early summer to reveal double flowerheads that are stunning for both the eyes and the nostrils.

Indeed, the deep blue lilac bloom is so heavily perfumed that you can even take cuttings to place around the home, and your household will be filled with a wonderful fragrance for days at a time.

Syringa vulgaris in a lilac garden

Depending upon the specific cultivar you choose, this blue flowering lilac can reach a maximum height of up to 4m in tree form, though it will obviously remain shorter as a shrub.

The species isn’t a fan of acidic soil, but other than that, it’s a very low-maintenance, high-reward choice for a low hedge, mixed flower bed or even indoor display.

It’ll do well facing any aspect, but if planting in a spot that’s particularly susceptible to full sun, remember to mulch it occasionally to retain some moisture for the roots.

5) Rose Of Sharon ‘Blue Chiffon’

blue rose of sharon flower
  • BOTANICAL NAME: Hibiscus syriacus

Otherwise known as Blue Chiffon, this eye-catching hibiscus is a medium-sized deciduous shrub with palmately lobed leaves, its points spreading out from the stem liked fingers on a hand.

Every year, the foliage serves as background to beautiful pale-blue blooms with layer upon layer of papery petals, the outermost bearing a purplish stain at their centre.

Indeed, it’s the layering of those petals which give the Blue Rose its alternative moniker; the flower itself resembles a pile of ruffled chiffon.

close up of Hibiscus syriacus Blue Chiffon

It’s a reliable shrub that has been awarded the RHS Award of Garden Merit, meaning you know you’re getting a quality plant when you settle upon it as part of your floral garden display.

Growing up to a maximum of two metres in height, the hibiscus serves equally well as a standalone plant or as a low hedge as it does in tandem with other shrubs around it.

It loves the sun but prefers shelter from the wind, while it requires little maintenance other than trimming back to keep it from encroaching on surrounding species.

6) California Lilac

small California lilac shrub with lawn in background

Ceanothus are arguably the most impressive and instantly recognisable of all blue-flowering shrubs, coming in both deciduous and evergreen varieties.

Indeed, there are so many different strains available that you can even select whether you’d prefer a spring, summer or late-blooming addition to your garden, offering maximum flexibility in your options.

Whichever variety you choose, you’re guaranteed to enjoy a sea of colour when the shrub is in full bloom, with its dense foliage carpeted in blossoms of its characteristic blue (although pink and white flowering alternatives are available).

large ceanothus bush with many blue flowers

They look particularly impressive when trained against a south-facing fence or wall, but can also serve as low hedges or border plants.

Like other lilacs, this species can be prone to flowering profusely one year, then producing nothing the next.

To avoid that problem, remove the blooms after they have lost their vibrancy but before the seeds begin to form.

You can also instigate more growth by clipping back those stems which have already flowered more than once.

7) Chinese Wisteria

purple wisteria blooms in an Italian public garden
  • BOTANICAL NAME: Wisteria sinensis

Unlike all of the other plants mentioned on this list, Chinese wisteria won’t necessarily be confined to your garden.

As a prolific climbing shrub, wisteria can completely transform the exterior of your home, trailing up around doors and windows and adding a spectacular aesthetic to your building’s façade.

It is characterised by blue, purple or pink drooping blooms each year.

When choosing a wisteria specimen to introduce into your garden, ensure that you get one that has been bred by grafting rather than from seed, since the latter variety can take decades to produce flowers.

trailing blue flowers of Chinese Wisteria

Grafted wisteria is immediately discernible by the bulbous growth at the base of its stem, while all varieties of this breath-taking climber demand plenty of sunshine.

For best results, position the plant against a sturdy wall and fix wires in place across it to train the new growth.

You can plant the wisteria in a pot, but it’ll do much better in the earth itself, while a fully mature specimen can swell to the size of a small tree trunk, so ensure the surface that you plan to train it against is stable and can support its weight as it grows.

Prune twice a year, in January and July, to ensure that the wisteria follows the path you have laid out for it.

8) Dutch Sky

large Clematis viticella flower with purple-blue shades
  • BOTANICAL NAME: Clematis viticella

Clematis is another climbing shrub, and though it might not produce as jaw-dropping results as wisteria, its faint blue flowers which subtly slide into a darker hue at the tips are a pleasing sight in themselves.

The blooms will occur between June and September and produce plentiful blossoms without fail each year, ensuring the wall, fence or other greenery they adorn enjoys a boost of colour.

Despite their name, the sky isn’t the limit for Dutch Sky plants – they rarely reach a height in excess of two metres, but their spread can exceed one metre comfortably.

Plant them in any type of fertile soil which enjoys good ventilation and ensure they receive at least partial exposure to sun and you’ll have no problems whatsoever with this low-maintenance climbing shrub.

close up on the stamen of large Clematis viticella flower

They’re also not as structurally demanding as wisteria, meaning they can be trained to climb trees, shrubs and other plants in the vicinity.

Another variety to consider is Clematis Fukuzono, a rare Japanese strain which features incredible bluish-purple flowers at will.

When planted alongside Dutch Sky, Fukuzono will complement the subtle, pastel colours of the former with its own bold palette, creating a stunning display of climbers wherever they appear.

9) Hydrangea ‘Nikko Blue’

nikko blue hydrangea blooms
  • BOTANICAL NAME: Hydrangea macrophylla

Nikko Blue is remarkable for the rounded globes of its flowerheads, in which individual blossoms group together to create a mophead effect of metallic blue.

As such, it’s an excellent cut flower in its own right and will work exceptionally well as a hedge or border plant.

In fact, the sharp contrast between its vibrant flowers and lush foliage make it versatile for planting anywhere you wish.

Aside from its attractive floral display, another strong selling point of Nikko Blue is its fast-growing properties.

blue Hydrangea macrophylla

In just two or three years, a seedling plant can reach its full height of over 1.5m, providing a convenient screen to create privacy without having to sacrifice on aesthetic impression – or wait forever and a day for the plant to provide adequate cover.

Like most hydrangeas, Nikko Blue likes partial sun and moist terrain that enjoys good drainage.

It should be protected from the worst ravages of the wind – especially as a younger specimen – but once established, it will require very little in the way of any maintenance whatsoever, except for perhaps the occasional pruning to keep it in shape.

You might need to undertake some efforts to keep your hydrangea blue, but we think it’s well worth the spectacle!

10) Russian Sage

panicles of Russian Sage with blue and purple flowers
  • BOTANICAL NAME: Perovskia atriplicifolia

Characterised by dense tangles of thin, grey-green stems dotted with blue or lavender flowerheads, Russian Sage can lend its environment an aura of weightlessness and calm.

It will bloom slightly later in the year than some other options and hold its blossoms well into autumn, making it a great choice if you wish to prolong the displays in your garden.

It’s beautiful but austere aesthetic means it may work best when planted in a gravel garden or as part of a herbaceous border.

Its blooms also attract plenty of bees, butterflies and other pollinators, meaning that it can enhance biodiversity, especially when planted among complementary shrubs which do the same.

bee harvesting pollen from the blue flowers of Russian Sage

One of the hardiest plans on this list, Russian Sage is all but impervious to droughts and pests, though it does prefer full sun and may require protection in colder parts of the UK during winter.

It can grow to over a metre in height and may require support if cultivated individually; alternatively, you can plant it in batches to provide mutual support.

Careful pruning should be conducted once a year to promote growth when you want it and prevent it when you don’t.

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