11 Of The Best Blue Flowering Shrubs
These blue flowering shrubs add a vibrant splash of blue to the backbone of any garden setting. From the serene hues of hydrangeas to the rich azure of ceanothus, these plants offer a stunning range of blue tones for you to enjoy.
There is no secret that I love blue (all shades of blue!), whether it be in the garden, in my home décor or my clothes.
In my garden, I gravitate to plants that have blue flowers and blue tinted foliage.
They are not always easy to find because blue is not a pigment often found in plants. Especially in shrubs.
Breeders have worked hard to introduce it but most of the plants that are labelled blue are not a true clear blue, but rather a shade of purple with blue overtones.
So finding and using blue flowering bushes is a labor of love.
However, there are some blooming bushes that I think have the best blue flowers (as close to blue as they come).
Here are the ones that fall into that category.
1 | ‘Beyond Midnight’ Bluebeard
Scientific name: Caryopteris x clandonensis ‘Beyond Midnight’
Zone: 5 to 9
Exposure: sun
Height: 2′ to 2’6″
Width: 2′ to 2’6″
Bloom time: summer
Flower color: deep blue
‘Beyond Midnight’ Caryopteris is an exciting new compact shrub that adds gorgeous deep blue color to the late summer border.
It does well in a sunny location in very well-drained, humus-rich soil.
I think ‘Beyond Midnight’ is definitely the most blue shrub out there.
And would look very pretty along side yellow or orange blooming perennials
Bluebeard (also known as Blue Mist Shrub) is an easy care deciduous plant, with dark glossy leaves, and intense blue flower spikes, that is best planted in the Spring.
No dead heading is necessary. But the entire plant should be cut back to new buds in the spring to encourage a bushy growth habit.
Note that Caryopsis is sometimes called blue spirea but it is in no way related to spireas.
Other varieties to try:
- C. ‘Longwood Blue’ – medium-sized shrub (to 4′ tall) with silvery foliage and a long bloom time.
- C. ‘Dark Knight’ – medium-sized (to 5′ tall) with dark blue flowers.
2 | ‘Blue Bird’ Rose of Sharon
Scientific name: Hibiscus syriacus ‘Blue bird’
Zone: 5 to 9
Exposure: sun
Height: 8′ to 12′
Width: 6′ to 10′
Bloom time: summer
Flower color: blue with lavender tinge
If you are looking for a much larger bush with blue flowers that blooms in the summer, you will like ‘Bluebird’ Rose of Sharon. The prolific large, single blooms are a lighter blue with a purple center and a white stamen.
This deciduous, upright bush makes a good hedge or specimen in the perennial border.
It stands out in late summer and early fall when the foliage is covered in masses of long blooming flowers.
Bees, butterflies, and hummingbirds, as well as humans, love it. Deer do not.
Rose of Sharon is a low maintenance shrub that tolerates any well drained soil with medium moisture.
It may be cut back in the spring, as it blooms on new wood, but pruning isn’t necessary. The habit of this bush is naturally rounded.
Other varieties to try:
- ‘Blue bird’ can self-seed in the right conditions so if you’re looking for a low seed-set Rose of Sharon, try ‘Azurri Blue Satin’.
- H. ‘Blue Chiffon’ — lavender blue flowers with a ruffled center and low seed set.
3 | Big leaf Hydrangeas
Scientific name: Hydrangea macrophylla
Zone: 3 to 7
Exposure: part shade
Height: 3′ to 6′ depending on the variety
Width: 3′ to 6′
Bloom time: summer
Flower color: blue if planted in acidic soil
Many of the very popular bigleaf Hydrangeas can have blue flowers.
In my view there is nothing more spectacular than a Hydrangea hedge covered with big 6″ diameter blue globes foiled by serrated, large dark green leaves.
However, their unique characteristic is that their color is dependent on your soil ph.
Be sure to buy a blue-blooming variety and plant it in acidic soil, with a PH of 5.5 or lower. Then it will continue to produce large, clear blue round, or flat lace-cap flower clusters.
You can adjust the soil to lower the PH by adding aluminum sulphate to it.
Note that if your soil is alkaline, the flowers will turn pink. And if you purchase a white blooming macrophylla it will always bloom white.
Your easy care Hydrangea macrophylla needs to be planted in moist, well-drained humous-rich soil, ideally where it will get afternoon shade. It requires an inch of water weekly. Apply a good layer of mulch annually in the spring to retail moisture.
I do not prune my bigleaf hydrangeas because they bloom on old wood. Even the reblooming varieties bloom on old wood first. For more information, read our Hydrangea pruning tips.
Leave the brown dead-heads for winter interest, then snip them off just below the old flower head in spring. Remove old hollow dead stems by pulling them out.
If you are going to fertilize, apply a slow release fertilizer meant for Hydrangeas at the same time.
These deciduous multi stemmed shrubs are available in a variety of sizes so assess your location and purchase accordingly.
Pollinators are attracted and so are deer. All parts of the plant are poisonous to humans and pets.
Late frost will kill the emerging flower buds which can result in no blooms. To get around this, purchase reblooming varieties, winter wrap in burlap and mulch below zone 6. Try ‘Rhythmic Blue,’ a rebloomer in the Let’s Dance series.
Buy big leaf Hydrangeas here.*
4 | Tuff Stuff Mountain hydrangea
Scientific name: Hydrangea serrata
Zone: 5 to 9
Exposure: part shade
Height: 2′ to 4′
Width: 2′ to 4′
Bloom time: all summer
Flower color: blue/purple (in acid soil)
The Tuff Stuff series of Mountain Hydrangeas is a reliable reblooming cultivar with large 6″ flat lace cap flowers that is hardy from Zones 5 to 9,
These shrubs grow in the same conditions as the Big Leaf Hydrangeas.
And have the same requirement that acidic soil is required for beautiful blue/purple blooms.
However, the Mountain Hydrangea is a smaller, more compact bush shrub that is perfect for smaller gardens, containers or toward the front of the border.
It is also susceptible to late frost kill of immerging buds.
5 | California Lilac
Scientific name: Ceanothus
Zone: 8 to 10
Exposure: sun, partial shade
Height: anywhere from ground cover to 30′ depending on the variety
Width: 10′ to 12′
Bloom time: late spring or late summer, depending on the variety
Flower color: deep blue(most usual), purple, pink, or white
Ceanothus is a California native shrub that grows very quickly.
It may be evergreen or deciduous, a mounding groundcover or a tall shrub depending on the variety.
Most bloom a lovely strong blue color.
This shrub needs consistent moisture the first year and then bimonthly watering.
Plant in any well draining soil that is not soggy.
Prune lightly in the summer, if necessary, to promote denser growth.
The intensely fragrant flower clusters attract pollinators and hummingbirds.
Some blue flowering cultivars are:
- C. ‘Victoria’–evergreen shrub with indigo blue flower clusters
- C. ‘Concha’– clumping variety with deep blue clusters of flowers.
- C. ‘Dark Star”– smaller clusters of cobalt blue blooms with yellow stamens.
- C. thyrsiflorus var. repens — An evergreen creeping variety with blue flowers.
- C. x delileanus ‘Gloire de Versailles’ — clear blue flowers on a low growing rounded shrub. Produces clusters of red berries.
- C. ‘Julia Phelps’– Very drought tolerant, with small leaves and vibrant blue blossoms
6 | Chaste tree
Scientific name: Vitex agnus castus
Zone: 5 to 9
Exposure: sun
Height: 3′ to 25′ (depending on the variety)
Width: 3′ to 25′ (depending on the variety)
Bloom time: summer
Flower color: lavender/blue
How I wish I had a sunny site so that I could add one of the dwarf versions of the Chaste Tree shrub to my garden. (I just love the large one in Wanda’s garden above!)
With its panicles of blue flowers and bright green leaves, it’s a stunning addition to any garden.
This shrub will withstand periods of drought, road salt and deer.
And it attracts butterflies.
It can be pruned in spring if desired because it blooms on new wood.
In fact, it is slow to break bud, so be patient and do not assume it is dead.
In colder zones it should be cut to the ground in Spring. It will rapidly grow new stems and bloom in the summer months.
Some of the blue cultivars are:
- V. ‘Blue Diddley’ — a dwarf variety that grows 3′ to 6′ tall and wide.
- V. ‘Blue Puffball’– another dwarf variety that does well in containers. Grows 4′ tall and wide.
- V. Abbeville Blue’ — blue flowers, 10′ – 20′ tall
- V. ‘Delta Blue’ — compact to 10′ tall
- V. ‘Latifolia’ — lavender/blue flowers, green/blue foliage to 15′ tall
7 | Plumbago
Scientific name: Plumbago auriculata
Zone: 9 to 11
Exposure: sun
Height: 5′
Width: 6′ to 10′
Bloom time: spring through fall
Flower color: blue
Plumbago (also known as Cape Leadwort) is a deer resistant, evergreen, shrubby climber with prolific blue blooms that resemble garden phlox,
It looks good covering a fence or as a groundcover on slopes where it controls erosion.
Space the plants 3′ – 5′ apart to provide room for its rapid growth.
Water consistently the first year then less frequently.
This shrub benefits from the application of an all purpose fertilizer in the spring.
This South African native, which is toxic to birds and animals, has adapted well to Florida’s tropical climate.
8 | ‘Pugster Blue’ dwarf Butterfly Bush
Scientific name: Buddleia x
Zone: 5 to 9
Exposure: sun
Height: 2′
Width: 2′ to 3′
Bloom time: summer through fall
Flower color: blue
‘Pugster Blue’ is an exciting addition to the blue plant world because of the vibrant true blue color of its flowers — a rarity to be sure.
The fragrant panicles are as large as the species Buddleia, on a very compact, hardy, small bush.
This deciduous shrub will bloom all summer until frost if planted in full sun. And it does not need deadheading.
The growing conditions are average soil that must by well draining. More buddleias die from root rot caused by wet winter conditions than from freezing conditions.
Do not mulch to avoid having the soil too wet.
Do not prune or plant in the fall, especially in zones 5 and 6. Wait until the plant has new growth in the spring and then prune hard to fat, healthy buds.
Be patient because buddleias are very slow to break dormancy.
‘Pugster Blue’ is not only drought tolerant and attractive to bees, butterflies and hummingbirds, it resists deer and rabbits.
Other blue varieties:
- B. Lo and Behold ‘Blue Chip Jr’ – a dwarf that only grows to 30 inches high.
- B. ‘Blue Heaven’ – another dwarf variety with lavender-blue flowers and a long bloom time.
9 | Blue glory bower
Scientific name: Rotheca myricoides ‘Ugandense’ (formerly Clerodendrum ugandense)
Zone: 9 to 11
Exposure: sun, part shade
Height: 6′ to 10′
Width: 5′ to 8′
Bloom time: summer
Flower color: light blue/violet (bicolor)
Rotheca myricoides ‘Ugandense’ is a broadleaf, evergreen, tropical plant that has long blooming, 5 petalled flowers shaped like a butterfly in flight — hence its common name, blue butterfly bush. (It is not the same as the butterfly bush above which is a Buddleia. This shrub is in the Lamiaceae family of plants.)
In its native environment, it grows 6′ to 10′ tall and wide.
For a bushier compact plant, cut back hard in the early spring.
This fast growing, easy care shrub likes humus rich, consistently moist, well drained soil and does best in partial shade.
It should be grown in containers and overwintered indoors in areas where the temperatures dip below freezing.
10 | Blue potato bush
Scientific name: Lycianthes rantonnetii
Zone: 11 to 12
Exposure: sun
Height: 3′ to 6′
Width: 3′ to 6′
Bloom time: summer
Flower color: blue/purple
Blue potato bush is an evergreen, tender shrub that has pretty fragrant, long blooming, blue/purple flowers with a yellow eye.
It is most often grown in containers that can be taken in because it does not tolerate temperatures below 40 degrees F.
Plant in organically rich well drained soil. It is somewhat drought tolerant. Prune for shape and size in the spring.
Although it is botanically related to edible potatoes, L. rantonnetii is grown for its ornamental beauty only.
It is a magnet for bees and butterflies.
11 | ‘Blue Baron’ Rhododendron
Scientific name: Rhododendron ‘Blue baron’
Zone: 6b to 8
Exposure: sun, part shade
Height: 3′ to 6′
Width: 3′ to 4′
Bloom time: late spring
Flower color: purple-blue
‘Blue Baron’ is an exotic looking evergreen rhododendron with dark green leaves and purple-blue flowers.
It is fussy about growing conditions and can be a little finicky to grow.
Best sited in a sheltered spot in partial shade, it needs humus-rich, acidic, well drained, moderately moist soil.
It does not tolerate standing water or heavy clay.
Often Blue Barron needs a burlap wrap and extra mulch over the shallow root system for winter protection of the flower buds.
The foliage turns bronze in the fall to extend the seasons of interest.
This plant tends to be leggy so prune for shape just after the blooms are spent.
Other blue flowering plants you might like
- Blue blooming annuals for shade
- Blue flowering perennials
- Early spring blue flowers
- Blue and white garden ideas
Or browse all of our plant lists.