8 blue-flowering shrubs every garden should have
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From sky blue to cyan, from midnight blue to ultramarine or indigo, blue-flowering shrubs are always highly sought after in gardens. Here we are talking about true blue: the blue that softens overly vivid tones or beautifully enhances green foliage, the blue that adds intensity or creates contrast, for example alongside yellow-flowering plants, or that can also be part of a blue garden. Discreet or intense, clustered or star-shaped, the flowering of these shrubs always creates charming, soothing scenes. Blue-flowering shrubs are perfect in cottage gardens and naturalistic gardens. Easy to pair, whether in hedges or borders, planting blue flowers is essential! To help you choose, we offer a selection of the 8 most beautiful blue-flowering shrubs: discover them!
Buddleja davidii or butterfly bush
From June to October, Buddleia produces abundant scented flower spikes, frequented by numerous butterflies drawn to their fragrance. It comes in a range of colours, notably some very beautiful blues, such as the striking deep blues of Buddleia davidii ‘Adonis Blue’ with large flower panicles 20–30 cm long in an intense midnight blue, or the lavender-blue panicles of Buddleia davidii ‘Nanho Blue’. Buddleia is among the easiest flowering shrubs to grow and thrives in sun in any well-drained soil, even the poorest. Fast-growing, it quickly forms attractive leafy, flowering screens; plant in groups or as a specimen, at the back of shrub borders or in informal, country-style hedges. It suits natural, low-maintenance gardens as well as scented gardens. It pairs well with all kinds of shrubs, such as Ceanothus or California lilac, altheas and lavateras that flower at the same time, but you can also combine it with other Buddleias for a palette of blues or with sun-loving perennials such as purple sages, lupins or delphiniums.
Find all our blue-flowering Buddleias in our online nursery, along with all the information you need to grow them in this care sheet: “Buddleia, Butterfly tree: planting, pruning, care”
Ceanothus or California lilac
Whether deciduous or evergreen, this shrub is highly prized for its generous, fragrant spring or summer flowering, reminiscent of lilac. It produces some of the garden’s most beautiful blue flowers. Its handsome pyramidal inflorescences come in endless shades of blue, as with the Ceanothus ‘Blue Diamond®’ and Ceanothus ‘Skylark’ with deep-blue flowers. Easy to grow, it will thrive in ordinary, well-drained soil, in full sun or partial shade and even in a pot! It suits all gardens, as a specimen or grouped in informal hedges with other shrubs such as Buddleias, mock orange, altheas, in a mixed border with the attractive foliage of hydrangeas or Mexican orange blossom. It provides an attractive backdrop for shrub roses and works particularly well with yellow-flowering shrubs such as brooms and cytises.
Find all our blue-flowering Ceanothus in our online nursery, together with gardening advice from our experts in our guide: “Ceanothus: planting, pruning and care”
Caryopteris or "blue spirea
Le Caryopteris or “Blue Spirea” is an elegant shrub prized for its airy flowering in endless shades of azure and for its silvery, variegated or golden aromatic foliage that rustles. Its rather late flowering from August to October follows summer blooms. This small shrub, rarely exceeding 1.5 m in height, brings a touch of freshness right up to the onset of winter, both to English gardens, to naturalistic or wild gardens and to urban gardens. It is a sun-loving, dry-soil shrub, hardy and easy to grow that slips easily into a flowering hedge, into a border or even onto a sunny terrace! Play with shades of blue and pair the particularly intense blue‑violet summer flowering of Caryopteris (x) clandonensis ‘Heavenly Blue’ or Caryopteris ‘Grand Bleu’ with Russian sage (Perovskia atriplicifolia) which blooms at the same time, with asters in similar azure tones, with Ceanothus, with buddleias or play the contrasts by pairing it with the yellow flowers of Michaelmas daisies and Helenium.
Find all our Caryopteris or “Blue Spirea” in our online nursery as well as our 7 ideas for pairing with Caryopteris, and our complete guide: “Caryopteris, Blue Spirea: planting, pruning and maintenance”
Perovskia or Russian sage
Le Perovskia is a graceful small shrub that unfolds attractive aromatic silvery foliage and a delicate, airy azure-blue flowering that lasts all summer, sometimes until first frosts. A centrepiece for dry, wild gardens baked by the sun or exposed to sea spray, its vibrant, lavender-like silhouette brings a cool blue note. With its branching, airy spikes, it gives movement to sunny banks and large summer borders. A drought-tolerant plant par excellence, it grows in sun in poor, stony soils. We especially recommend the giant ‘Blue Spire’, which reaches 1.20 m in height, and the small ‘Lacey Blue’ with violet-blue flowers, not exceeding 50 cm in height. They structure wild-looking borders very well when mixed with Buenos Aires verbena, lavenders, their cousins the sages and ornamental grasses (Stipa, Miscanthus…).
Discover all our Perovskia in our online nursery as well as our complete guide: “Perovskia: planting, pruning and maintenance”
Hydrangea or hydrangea
Hydrangea is a deciduous shrub that instantly evokes the seaside and Brittany ! In summer it offers an impressive display of blooms, in globes, cones, flat heads or large panicles depending on variety. Varieties traditionally blue turn pink in neutral or calcareous soil. On alkaline soil, better to opt for container culture, using an acidic mix of heather soil, compost and potting compost; you will assuredly enjoy beautiful blue flowering. Versatile, hydrangea will find its place in a border, as a solitary specimen by the entrance, in an informal hedge or in a large pot on the terrace.
Hydrangea macrophylla and serrata are better suited to shady situations; ‘Nachtigall’, ‘Nikko Blue’, ‘Benelux’ will easily find a place in a woodland garden and surprise with their vivid blue inflorescences, as will Hydrangea serrata ‘Blue Deckle’ with its soft blue flowers. They will be perfect in dappled shade in a cottage garden or romantic garden. Plant with foxgloves, hostas, ferns, azaleas and thalictrums, for example.
Discover all our blue-flowering hydrangeas in our online nursery as well as our complete guide: “Hydrangeas: planting, pruning and care”
Ceratostigma or leadwort
Depending on species, the plumbago is a groundcovering and creeping perennial or shrubby (1.20 m all round), flowering from July through October–November. It is recognised by the star-shaped form of its flowers and, above all, their electric blue of exceptional intensity. It prefers warm positions and grows easily in gravelly soils, even in dry, stony ground. With its long flowering in an extremely vivid gentian blue, the Ceratostigma plumbaginoides will form superb combinations at the feet of yellow or orange flowers of shrubby shrubby potentillas, Sternbergia lutea (autumnal false crocus) and the golden foliage of Hamamelis or ornamental grasses. The Plumbago ‘Forest Blue’ (Willmott), with its cloud of stars in an extraordinary cobalt blue, will combine in a large border with the yellow blooms of tickseed, goldenrod and Helenium.
Discover all our plumbagos in our online nursery as well as our factsheet: “Ceratostigma: plant, prune and maintain”
Hibiscus
Hibiscus or Althaea is a handsome shrub prized for its magnificent summer display of corollas which are produced from July to October. While its simple or double, cup-shaped flowers occur in every shade of pink, some varieties such as Althaea ‘Oiseau Bleu‘ produce bright blue trumpets with a deep red centre, Hibiscus syriacus ‘Ultramarine’ with lavender-blue flowers and a purple centre or Hibiscus syriacus ‘Blue Chiffon’ with double lavender-blue flowers. Easy to grow in rich, moist, well-drained, neutral soil in a sunny position, it also tolerates partial shade.
It can reach 3 m at maturity and makes a marvellous specimen planted alone in the middle of a lawn, but can also be included in a flowering hedge alongside other flowering shrubs such as buddleja or abelia. It also finds its place at the back of a summer border with country perennials such as gauras, phlox or asters. It brings an exotic touch to English cottages and even to urban gardens, as it tolerates pruning well.
Choose your blue-flowering hibiscus from our online nursery and consult our fact sheet: “Hibiscus, Althaea: plant, grow and maintain”
Vitex or chaste tree
Vitex is a handsome shrub with fragrant flowers, most often a bright blue in summer and attractive foliage that gives off a peppery scent. From July to October, when blooms are scarcer in the garden, its spike-like flowering reminiscent of butterfly bushes unfolds in magnificent shades of lavender blue to deep violet-blue, as in ‘Blue Puffball’, and Vitex agnus-castus ‘Delta Blues’.
This all-rounder, which grows anywhere in sun, even in poor soils, is suitable for both large and small gardens, planted singly, at the back of a perennial border, grouped in informal hedges, or in containers. It pairs easily with many types of plants in a natural garden or by the seaside as it tolerates sea spray well. It is splendid in a flowering hedge mixed with all kinds of flowering shrubs such as Ceanothus or California lilac, Weigelas, a smoke tree, butterfly bushes and with perennials with blue flowers such as Delphiniums, Knautia arvensis, Echinops, and Perovskia.
Discover our range of Vitex in our online nursery and our advice on how to grow it in our complete guide: Vitex agnus-castus, Chaste tree: plant, grow, prune
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