Shrubs that produce blue flowers hold a special place in gardens because blue is one of the rarest flower colors in nature. These plants bring a cool, calming effect to landscapes and contrast beautifully with the greens, whites, and warmer tones of other plants. They are often chosen for their ornamental value, as their blooms can create striking focal points in borders, hedges, or mixed beds.
The appeal of blue-flowering shrubs also lies in their seasonal variation. Some bloom heavily in spring, filling gardens with a burst of early color, while others flower in summer or late into autumn, extending the display when many other shrubs have faded. They’re good in maintaining continuous interest in gardens throughout the year. Also, their blossoms are usually rich in nectar and pollen, drawing in bees, butterflies, and sometimes hummingbirds.
These shrubs also vary greatly in form and size, ranging from low, ground-hugging types that spread across garden edges to tall, upright varieties that provide height and structure. Many are evergreen, adding year-round texture, while others are deciduous, often displaying attractive foliage or colorful seasonal changes in addition to their blue flowers.
Shrubs With Blue Flowers
Bluebeard (Caryopteris x clandonensis)
Bluebeard is a compact deciduous shrub cherished for its silvery-green foliage and profuse clusters of sky-blue flowers that appear from late summer into fall. It grows about 2–3 feet tall and thrives in sunny, well-drained sites. Its nectar-rich blossoms attract bees, butterflies, and other pollinators, making it a favorite for wildlife gardens.
Hydrangea (Hydrangea macrophylla – Blue Varieties)
Many bigleaf hydrangeas can produce vivid blue flowers when grown in acidic soils. These large, rounded shrubs can reach 6 feet tall and are best known for their mophead or lacecap blooms. Their blue hues can range from soft powdery tones to deep cobalt depending on soil pH and aluminum availability.
Plumbago (Plumbago auriculata)
Native to South Africa, plumbago is a sprawling, semi-evergreen shrub that produces abundant clusters of phlox-like, powder-blue flowers. It can grow 6–10 feet tall and wide, thriving in warm climates. Often trained on trellises or used as a flowering hedge, it blooms throughout summer and fall.
Blue Potato Bush (Lycianthes rantonnetii)
This evergreen shrub is prized for its deep violet-blue flowers with striking yellow centers. Growing up to 6–8 feet tall, it flowers profusely from spring to fall in mild climates. It responds well to pruning, making it suitable for shaping into hedges or patio specimens.
Butterfly Bush (Buddleja davidii) – Blue Cultivars
While butterfly bushes come in many colors, cultivars like ‘Lochinch’ and ‘Empire Blue’ produce soft lavender-blue flower spikes. Growing 6–12 feet tall, this shrub is beloved for attracting butterflies and hummingbirds. It thrives in sunny sites and blooms from midsummer to frost.
Texas Bluebell Shrub (Eustoma exaltatum subsp. russellianum)
Though more often seen as a perennial, shrubby forms of Texas bluebell can develop woody bases, producing showy blue to violet flowers resembling roses. Native to the southern U.S., it blooms in warm months and thrives in full sun and well-drained soils.
Ceanothus (Ceanothus spp. – California Lilac)
Ceanothus, often called California lilac, is a versatile evergreen shrub native to North America. It produces abundant clusters of deep blue flowers in spring, creating a stunning display. With species ranging from groundcovers to 15-foot shrubs, it’s highly drought-tolerant and well-suited to Mediterranean climates.
Rosemary (Salvia rosmarinus)
Though often grown as an herb, rosemary is a woody evergreen shrub with small, aromatic leaves and delicate blue to violet flowers. The blooms appear in spring and often again in fall, attracting bees. It grows up to 4–6 feet and thrives in poor, dry soils.
Russian Sage (Perovskia atriplicifolia)
This woody sub-shrub is admired for its silvery foliage and tall spikes of airy blue-purple flowers from midsummer to fall. Growing 3–5 feet tall, it thrives in sunny, dry areas and adds texture and movement to landscapes. It’s drought-tolerant and pollinator-friendly.
Blue Hibiscus (Alyogyne huegelii)
Native to Australia, the blue hibiscus is an evergreen shrub with large, showy, blue-mauve flowers resembling true hibiscus. It grows 6–10 feet tall and blooms generously from spring to autumn in warm climates. Its striking blooms make it a popular ornamental shrub.
Blue Daze (Evolvulus glomeratus)
A low-growing woody shrub, Blue Daze produces masses of small, sky-blue flowers with silvery-green foliage. It blooms continuously in warm weather, making it ideal for borders, groundcovers, or container plantings. While compact, it creates a brilliant carpet of blue color.
Leadwort (Ceratostigma plumbaginoides)
Leadwort is a semi-woody shrublet that grows 1–2 feet tall, prized for its intense cobalt-blue flowers appearing in late summer and fall. Its foliage turns brilliant red in autumn, extending its seasonal appeal. It’s drought-tolerant and makes an excellent groundcover.
Mexican Blue Sage (Salvia chamaedryoides)
This shrubby sage is native to Mexico and valued for its silver-gray foliage and true-blue flowers that bloom repeatedly from spring to fall. It grows 2–3 feet tall and thrives in hot, dry sites, making it ideal for xeriscaping.
Blue Mist Spirea (Caryopteris incana)
Closely related to Bluebeard, this deciduous shrub grows 2–4 feet tall and produces delicate, misty blue flowers in late summer. Its aromatic foliage enhances its ornamental value, and the blooms are magnets for pollinators.
Hebe (Hebe ‘Blue Gem’)
Hebes are evergreen shrubs from New Zealand, and ‘Blue Gem’ is one of the most striking cultivars with violet-blue flower spikes. Compact and dense, it grows about 3–4 feet tall and provides color throughout summer, often repeating blooms in autumn.
Chaste Tree (Vitex agnus-castus)
Though sometimes considered a small tree, the chaste tree often grows as a large multi-stemmed shrub. It produces long spikes of lavender-blue flowers in summer, highly attractive to bees and butterflies. It’s drought-tolerant and thrives in hot, sunny locations.
Blue Passionflower Shrub (Passiflora caerulea – Shrubby Form)
Though usually a vine, passionflower can be trained as a shrubby form, producing exotic blue and white flowers. The blooms are intricate and fragrant, often followed by edible fruits. It thrives in warm climates and adds tropical flair to gardens.
Shrubby Germander (Teucrium fruticans)
This evergreen shrub produces small but abundant blue to violet flowers throughout summer. With silvery foliage and a bushy growth habit, it grows up to 4–6 feet tall. Native to the Mediterranean, it is drought-tolerant and ideal for coastal or arid landscapes.
Blue Rhododendron
Blue Rhododendron (Rhododendron ‘Blue Tit’) is a compact evergreen with trumpet-shaped blue-purple flowers in spring. Growing 2-3 feet tall in USDA zones 6-8, it prefers partial shade and acidic, well-drained soil, making it suitable for rock gardens or borders.
Princess Flower
Princess Flower (Tibouchina urvilleana) showcases large, velvety purple-blue blooms intermittently year-round, with fuzzy leaves adding texture. This tropical evergreen reaches 5-10 feet in USDA zones 9-11, thriving in full sun to partial shade and acidic soil for patios or borders.
California Lilac
California Lilac (Ceanothus spp.) is an evergreen shrub with dense clusters of fragrant blue flowers in spring, native to western North America. It varies from 3-20 feet tall in USDA zones 8-10, thriving in full sun and dry, well-drained soil, perfect for slopes or wildlife habitats.
Rose of Sharon
Rose of Sharon (Hibiscus syriacus) is an upright deciduous shrub with large, hollyhock-like blue flowers blooming from mid-summer to frost, attracting pollinators. Growing 8-12 feet tall in USDA zones 5-9, it tolerates heat and drought, making it great for hedges or screens in full sun.