20 Blue Flowers for Your GardenTurn your garden from blasé to blue-tiful with easy-to-grow perennials, annuals, and shrubs
Dutch painter Vincent Van Gogh may not have been a gardener, but he was clearly an admirer of blue flowers, perfectly capturing their beauty in his famous painting Irises (1889). Perhaps as an artist he knew Mother Nature’s secret to producing “true" blue flowers, which is actually a blend of plant pigments that reflect light in such a way to create the illusion of natural blue. (Even flowers can benefit from the right lighting!)
Making up less than 10% of the flowering plant kingdom, plants with blue blooms are a rarity, but you still have many options. This elite color group includes a wide range in shades ranging from sky blue to deep indigo and growth habits from groundcovers to large shrubs. And if you plan carefully, your garden will be singing the blues from early spring through late fall.
BLUE PERENNIAL FLOWERS
‘Jack Frost’ Siberian Bugloss — Buy now from Proven Winners
Also called heartleaf brunnera and false forget-me-not, this shade-loving beauty is grown as much for its foliage as it is for its lovely sprays of tiny baby-blue flowers in spring. Large heart-shaped leaves overlaid with silver create a luminous glow in the shade garden throughout the growing season.
Size: 12 to 15 inches tall and wide
Where to grow: Shade to partial sun in moist, well-drained soil. Ideal for use as a groundcover in a woodland setting.
Bloom time: Late April to June
Growing tip: If the beautiful foliage begins to brown as the summer wears on, simply cut the leaves back to the ground to encourage new growth.
Others to try: ‘Emerald Mist’, ‘Sea Heart’, ‘Sterling Silver’, ‘Looking Glass’
Decadence® 'Blueberry Sundae' False Indigo — Buy now from Proven Winners
This tough, drought-tolerant perennial produces elegant spires of pea blossom-shaped flowers in late spring that last well into summer. The intense indigo-blue flowers are set off by vase-shaped mounds of blue-green foliage that remain attractive all season. Once the flowers have finished blooming, they develop into large, black seed pods that rattle gently in the breeze and linger on the plant to provide winter interest.
Size: 2½ to 3 feet tall and wide
Where to grow: Full sun in average, well-drained soil. Can tolerate some shade, but the best flowering occurs in a sunny location.
Bloom time: Late May to July
Growing tip: Deep taproots enable them to thrive during periods of drought, but make it very difficult to uproot and divide them. Transplanting and dividing is best done while plants are still young.
Others to try: Midnight Prairieblues™, ‘Blue Towers’
Learn more about growing baptisia.
’Blue Suede Shoes’ Bearded Iris
Iris germanica 'Blue Suede Shoes'
This spectacular sapphire-blue iris wasn’t around during Van Gogh’s time, but it bears a striking resemblance to the irises captured in his famous painting. The large ruffled blooms, accented by bright yellow beards, make their dramatic debut in the spring only to come back for an encore later in the summer.
Size: 36 to 39 inches tall, up to 2 feet wide
Where to grow: Full sun in average, well-drained soil.
Bloom time: Mid to late spring and again in late summer
Growing tip: Plant so the tops of the rhizomes are exposed and the roots are spread out facing downward in the soil. The best time to plant is in late summer to early autumn to give the roots plenty of time to become established.
Others to try: ‘Breakers’, ‘Astro Blue’, ‘Baja Blue’
Learn more about growing irises.
Summer Cloud Delphinium — Buy now from Proven Winners
For breathtaking blue flowers all summer long, delphinium has few rivals. Selections in the grandiflorum group have the added advantage of a more compact growth habit, so they never need staking. They also have better heat tolerance, allowing them to fare well even during the dog days of summer. If you take a little time to remove the spent flowers, you will be rewarded with blue blooms through early fall.
Size: 12 to 18 inches tall and wide
Where to grow: Full sun in moist, well-drained soil
Bloom time: Late spring through summer
Growing tip: Although delphiniums tend to be short-lived, they will often self-sow if you let them go to seed or you can propagate them from stem cuttings in early spring.
Others to try: ‘Blue Butterfly’, ‘Blue Mirror’, ‘Summer Blues’
Learn more about growing delphiniums.
’Blue Yonder’ Lily of the Nile
These blue-flowered wonders from South Africa produce huge globe-shaped flower clusters in hues ranging from dark blue-violet to pure white. Resembling a fireworks display, the flowers are held high above clumps of narrow leaves. After blooming, the seedpods that follow are almost as attractive as the flowers themselves and make great additions to winter floral arrangements.
Size: 4 to 5 feet tall, 1 to 2 feet wide (with the exception of dwarf forms)
Where to grow: Full sun in well-draining soil. Adapts to a wide range of soil types.
Bloom time: July to September
Growing tip: Keep plants well-watered during periods of drought. Dry conditions, especially later in the season, can result in poor flowering the following year.
Others to try: ‘Little Galaxy’, ‘Storm Cloud’, ‘Blue Wave’
Learn more about growing lily of the Nile.
With bright pink buds that open into delicate sky-blue bells, this charming spring-blooming native wildflower naturalizes easily when grown in a moist, shady environment. Although the show is brief and the plants go dormant in early summer, they will return with renewed vigor the following spring. For a breathtaking show, combine with daffodils, celadine poppy, pink tulips, and columbines.
Size: 12 to 18 inches tall and wide
Where to grow: Filtered shade in moist, humus-rich soil.
Bloom time: April to May
Growing tip: Because bluebells die back early in the season, fill the void left by their absence with summer annuals or plant them among large-leaved perennials, such as hostas.
‘Rapido Blue’ Carpathian Bellflower — Buy now from Proven Winners
One of the showiest blue-flowered groundcovers, this low-growing perennial becomes smothered with upturned, bell-shaped flowers in spring, creating a colorful carpet of blue that lasts through most of the summer. Excellent for use in rock gardens, the front of the border, or to edge garden pathways.
Size: 5 to 7 inches tall, 5 to 8 inches wide
Where to grow: Full sun in average, well-drained soil. Prefers afternoon shade in warmer climates.
Bloom time: Early spring to summer
Growing tip: Many bellflowers self-sow but not to the point of becoming invasive. To prevent their spread, deadhead your plants or cut them back after their first flush of bloom. Deadheading will also encourage some repeat blooming.
Others to try: ‘Deep Blue Chips’, ‘Pearl Deep Blue’, ‘Samantha’
Blue Danube Stokes’ Aster
Stokesia laevis ‘Blue Danube’
This prolific native wildflower sports frilly lavender-blue flowers up to 4 inches across that continue nonstop from late June until the first frost, especially if deadheaded regularly. In zone 9, it may even keep blooming through winter if you don’t allow it to go to seed. Stem cuttings last in a vase for a week or longer.
Size: 18 to 24 inches tall and wide
Where to grow: Full sun to partial shade in just about any soil type, as long as it has good drainage.
Bloom time: June through September
Growing tip: Stokes’ aster is very easy to divide from root divisions when you want more of it. Dividing your plants every three to four years will also keep them more robust and healthy.
Others to try: ‘Peachie's Pick’, ‘Blue Star’, ‘Klaus Jellito’
Globe thistle’s spiky, golfball-sized flower heads make a bold statement, both in the garden and in fresh or dried floral arrangements. Although the orbital blooms look similar to those of blue ornamental onions (Allium caeruleum), they emerge later in the summer and last for months, creating a dramatic backdrop to goldenrod, yarrow, ornamental grasses, and other summer-blooming perennials.
Size: 3 to 5 feet tall, up to 2 feet wide
Where to grow: Full sun in any soil with good drainage.
Bloom time: Late June to September
Growing tip: Here’s one blue-flowered plant that thrives on neglect. Long tap roots minimize the need for supplemental watering. And you can forget about fertilizing, which only makes plants floppy and shortens the blooming season.
Cultivars to try: ’Blue Glow’ (pictured), ‘Taplow Blue’, Veitch’s Blue’, 'Platinum Blue'
Magic Show® ‘Wizard of Ahhs’ spike speedwell — Buy now from Proven Winners
Although speedwell flowers come in an array of pinks, violets, purples, and whites, those with dark blue flowers are often the most arresting. ‘Wizard of Ahhs’ is prized for its exceptionally long bloom time. The blooms begin emerging in June and continue for months, creating an eye-catching vertical accent in garden beds or container arrangements.
Size: 18 to 24 inches tall and wide
Where to grow: Full sun in fertile, well-draining soil.
Bloom time: June to September
Growing tip: Although ‘Wizard of Ahhs’ will bloom for weeks, you can prolong the show and reinvigorate your plants by removing the flower spikes once they have faded.
Other blue speedwells to try: ‘Darwin’s Blue’, ‘Crater Lake Blue’, ‘Moody Blues Dark Blue’, 'Sunny Border Blue'
Learn more about growing speedwell.
Gentiana ‘True Blue’ — Buy now from Proven Winners
True to its name, this gentian’s blooms are a brilliant royal blue, set off by attractive emerald-green lance-shaped leaves. The tubular, upward-facing flowers bloom in profusion all along the stems, often continuing right into fall. A great choice for rock gardens, containers, and the middle of the border.
Size: 24 to 30 inches tall, 12 to 18 inches wide
Where to grow: Full sun to part shade in rich, acidic, well-drained soil. Protect from afternoon sun in climates with hot, humid summers.
Bloom time: Midsummer to early fall
Growing tip: Although gentians like soil that’s kept evenly moist, avoid planting in an area with overly wet soil in the winter, which can lead to root rot.
Other blue gentians to try: ‘Marsha’, Bottle Gentian (G. andrewsii)
BLUE ANNUAL FLOWERS
With its delicate flowers, ferny foliage, and ornamental seedpods, this classic cottage garden flower is a favorite for fresh and dried cut-flower arrangements. A number of delightful cultivars are available with large semi-double flowers in shades ranging from pale sky blue to denim. The plump seedpods that follow often sport purple or bronze stripes, making them an interesting addition to dried flower arrangements.
Size: 1 to 2 feet tall, up to a foot wide
Where to grow: Full sun in well-drained, fertile soil.
Bloom time: Spring through early summer
Growing tip: Easily grown from seed, which can be sown directly in the garden three to four weeks before the last spring frost. For continuous bloom all summer, make successive plantings every few weeks.
Cultivars to try: ’Miss Jekyll’, ’Oxford Blue’, ‘Moody Blues’
Also called “bachelor’s buttons," this old-fashioned favorite is popular in cutting gardens. These frilly flowers come in shades of blue, lavender, pink, and white, but the vivid blue color is so distinctive, it has even been replicated in a Crayola crayon. The nectar-rich blooms attract bees and butterflies and the small seeds are loved by goldfinches and other songbirds.
Size: 1 to 3 feet tall, 10 inches wide
Where to grow: Full to partial sun in average, well-drained soil.
Bloom time: Peak bloom time is early to midsummer, but blooms may be prolonged with frequent deadheading.
Growing tip: Easily grown from seed, cornflowers can be sown directly in the garden in early spring and again in midsummer for fresh blooms in the fall. In climates with warmer winters (zones 7-10) you can also sow the seeds in autumn for early blooms the following spring.
Cultivars to try: ‘Blue Boy’, ‘Blue Diadem’, ‘Dwarf Blue Midget’
Laguna® Sky Blue Lobelia — Preorder from Proven Winners beginning 12/1/20
This trailing lobelia is one of the best blue-flowered plants for containers and hanging baskets, producing cascades of tiny soft-blue flowers from spring until the first touch of frost. Although traditional lobelia tends to die back during hot weather, this heat-tolerant variety is bred to withstand sultry summer temperatures. Can be grown as a perennial in Zones 9-11.
Size: 6 to 12 inches tall, spreading up to 2 feet
Where to grow: Full sun to partial shade in average, well-drained soil.
Bloom time: Spring until frost
Growing tip: If flower production shows signs of waning in midsummer, give your plants a light trim to encourage additional branching and a new flush of blooms.
Other blue lobelias to try: Laguna® Compact Blue with Eye, ‘Crystal Palace’, ‘Hot Water Blue’, 'Techno Heat Light Blue'
Learn more about growing lobelia.
Rockin'® Playin' the Blues® Salvia — Preorder from Proven Winners beginning 12/1/20
When the gorgeous blue-violet flowers of this salvia finish blooming, the color show continues because the calyxes retain their deep-blue hue long after the flowers fade. Even better, new flower spikes continue to emerge all summer long, even without deadheading. The nectar-rich blooms and fragrant foliage are magnetic for many types of pollinators. Can be grown as a perennial in zones 7-10.
Size: 2 to 4 feet tall, 2 to 3 feet wide
Where to grow: Full sun to partial shade in average soil with good drainage. Can also be grown in containers.
Bloom time: Planting until frost
Growing tip: If you prefer a bushier plant with less height, trim it back to the size and shape you want. Not only will your plant look fuller, you’ll also encourage more flowers.
Other blue salvias to try: ‘Victoria Blue’, ‘Henry Duelberg’, Rockin'® Blue Suede Shoes™
Learn more about growing salvia.
‘Cape Town Blue’ Blue Felicia Daisy — Preorder from Proven Winners beginning 12/1/20
The daisy has become the poster child of the nearly perfect flower, but this South African version raises the bar by giving them heavenly sky-blue petals surrounding sunny yellow centers and a bloom season that lasts all summer into fall, even without deadheading. The compact growth habit and free-flowering nature make it a great choice for adding bursts of blue to containers, window boxes, rock gardens, and borders. Can be grown as a perennial in zones 10-11.
Size: 8 to 12 inches tall, 10 to 12 inches wide
Where to grow: Full sun to part shade in fertile, well-drained soil. Avoid wet soils.
Bloom time: Planting until frost
Growing tip: If plants become straggly in midsummer, give them a light pruning to make them look fuller and to jumpstart a new crop of flowers.
Others to try: ‘Forever Blue’, Variegated Blue Felicia Daisy (F. amelloides 'Variegata')
Blue My Mind® Dwarf Morning Glory — Preorder from Proven Winners beginning 12/1/20
This non-vining cousin of the traditional morning glory produces dainty true-blue blooms from early summer until the first frost, but won’t run amok in the garden. Spreading no more than 2 feet, it looks lovely spilling from containers and hanging baskets or trailing through the garden as a well-behaved groundcover.
Size: 6 to 12 inches tall, trails up to 2 feet
Where to grow: Full sun in well-drained soil.
Bloom time: Planting until frost
Growing tip: These heat lovers won’t tolerate cold. To prolong their growing season, put them in a container or a spot in the garden that can easily be sheltered from light frost.
Others to try: ‘Blue Daze’, ‘Hawaiian Blue Eyes’
BLUE FLOWERING SHRUBS
Beyond Midnight® Bluebeard — Buy now from Proven Winners
Caryopteris x clandonensis
Plants that give you blue flowers late into the season are few and far between, but this compact shrub produces them in abundance. The clusters of fragrant, deep-blue flowers last well into autumn, creating a striking contrast with many popular late summer flowers, such as coneflower and black-eyed Susan. A favorite of butterflies and other pollinators.
Size: 2 to 3 feet tall and wide
Where to grow: Full sun in well-drained soil. Sites with poor drainage and soggy soil can lead to root rot.
Bloom time: Midsummer through fall
Growing tip: It’s best to cut back bluebeard in early spring to promote new growth and flowers. You can give your plants a trim in late autumn to remove the spent flowers, but do not cut into the thick, woody stems until growth begins to emerge in spring.
Others to try: ‘Blue Mist’, Blue Balloon®, Petit Bleu™
Let's Dance® Rhythmic Blue® Hydrangea — Buy now from Proven Winners
This reblooming bigleaf hydrangea produces huge mophead flowers all summer long, even without pruning. It’s also bred to perform well in colder climates, making it a smart choice for northern gardens with harsh winters. The bloom color ranges from pink to lavender-blue depending on the soil pH. For the best blue blooms, keep your soil on the acidic side and treat it with aluminum sulfate.
Size: 3 to 4 feet tall and wide
Where to grow: Full sun to partial shade in moist, well-drained soil.
Bloom time: Midsummer to early fall
Growing tip: In addition to increasing the amount of aluminum in the soil, using a fertilizer that is low in phosphorous and high in potassium is also helpful in attaining the richest blue flower color.
Other blue hydrangeas to try: Let's Dance® Blue Jangles , ‘Nikko Blue’, ‘Decatur Blue’, ‘Blue Danube’
Learn more about growing hydrangeas.
Blue Chiffon® Rose of Sharon — Buy now from Proven Winners
Named 2020 Flowering Shrub of the Year, Blue Chiffon gives you lacy blooms from summer to fall on soft, elegant stems. Its flowers attract birds and butterflies and have a delicate, lacy center. A large shrub that is both heat and drought tolerant.
Size: 8 to 12 feet tall, 4 to 6 feet wide
Where to grow: Full sun in average soil
Bloom time: Early to late summer
Growing tip: Apply a slow-release fertilizer in early spring.
Others to try: Azurri Blue Satin®
Learn more about growing rose of Sharon and hardy hibiscus.