Blue Flowers: 35 True Blue — Not Purple, Actually Blue

Blue flowers are among the most sought-after plants in gardening — and among the rarest in nature. True botanical blue is difficult for plants to produce, which is why genuinely blue-flowering species command a premium at the nursery and hold a special place in garden design. A border anchored by blue flowers creates a serene, spacious feeling even in compact plots, and blue pairs beautifully with silver foliage, white blooms, and the warm contrast of yellow or orange.

This list of 35 blue flowers covers annuals for instant color, perennials for long-term structure, flowering shrubs for year-round presence, and spring and summer bulbs for layered seasonal interest. Each entry includes USDA hardiness zone information, approximate height, and a key care or design note to help you decide where it fits in your planting scheme.

Blue Annual Flowers for Instant Impact

Annual blue flowers are the fastest route to a blue-themed border. Most can be direct-sown and will bloom within 8–12 weeks, making them invaluable for filling gaps, trialing color schemes, or covering ground while perennials establish. Several of the most reliable — cornflower, forget-me-not, and larkspur — also self-seed freely, returning year after year with minimal effort.

1. Cornflower (Centaurea cyanus)

Cornflower produces some of the most intensely blue flowers in the annual world — a vivid cerulean with no violet tint. Native to European grain fields, it naturalizes readily and self-seeds freely. Dwarf forms like ‘Blue Midget’ suit containers and edging, while tall strains reach 36 inches. Direct-sow in fall or early spring; it germinates quickly in cool soil without stratification. A reliable magnet for honeybees and native bees throughout its long season. Annual, all zones.

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2. Forget-Me-Not (Myosotis sylvatica)

Forget-me-not creates clouds of tiny sky-blue flowers with a yellow eye from early spring through early summer. A biennial grown as a cool-season annual in most of the US, it self-seeds so reliably that a single planting perpetuates indefinitely. It combines beautifully with spring bulbs — the low blue haze sets off tulips and hyacinths perfectly. Best in partial shade in hot climates. Zones 3–8. Height: 6–12 inches.

3. Larkspur (Consolida ajacis)

Larkspur is the annual cousin of the perennial delphinium, producing tall spikes of ruffled blue, purple, pink, or white flowers from late spring into summer. The blue forms — particularly ‘Giant Imperial’ — achieve a rich gentian blue on spikes reaching 4 feet. Direct-sow in fall (or very early spring in cold climates) as it requires cool conditions to germinate well. Deer resistant. Note: all parts are toxic if ingested. Self-seeding annual, all zones.

4. Borage (Borago officinalis)

Borage is grown as much for its edible, star-shaped blue flowers as for ornamental effect. The intense blue of fresh borage flowers is remarkably pure, aging to pink as they mature — pick before they fade for the truest color. Grows 12–24 inches tall, sprawls attractively, and self-seeds freely. An outstanding bee plant: borage replenishes nectar so rapidly it is among the most attractive species for honeybees in mixed plantings. Annual, all zones.

5. Love-in-a-Mist (Nigella damascena)

Love-in-a-mist earns its poetic name from the feathery, misty green bracts surrounding each pale blue flower. The flowers are followed by ornamental inflated seed pods valued in dried arrangements. Blue forms like ‘Miss Jekyll’ produce a clear cornflower blue. Direct-sow in fall or early spring; it transplants poorly due to a taproot. Self-seeds reliably. Grows 12–18 inches. Annual, all zones. Combines especially well with pink and white cosmos for a relaxed cottage effect.

6. Morning Glory ‘Heavenly Blue’ (Ipomoea tricolor)

Morning glory ‘Heavenly Blue’ produces some of the largest and clearest blue flowers of any annual — trumpet-shaped blooms up to 4 inches across in an extraordinary sky blue fading to white at the throat. A vigorous twining climber reaching 8–10 feet in a season, ideal for fences, trellises, or mailbox posts. Blooms open each morning and close by afternoon. Nick or soak seeds overnight to improve germination. Annual in all zones.

7. Phacelia (Phacelia tanacetifolia)

Phacelia is a powerhouse cover crop that doubles as an ornamental, producing curling, crozier-like spikes of vibrant blue-violet flowers adored by bees. Studies from the UK have found phacelia attracted more bumblebee species than any other flowering crop tested. Grows 12–36 inches tall; direct-sow from early spring in poor, dry soil. In hot climates, sow in fall for spring bloom. Self-seeds freely. Annual, all zones — one of the most pollinator-dense choices in this list.

8. Blue Lobelia (Lobelia erinus)

Blue lobelia is the classic edging plant for containers and hanging baskets, producing a continuous cascade of tiny blue flowers from spring until frost. ‘Crystal Palace’ delivers a rich true blue; ‘Sapphire’ offers blue petals with white centers. Prefers cool weather — in the South it performs best in spring and fall, going dormant in midsummer heat. Grow from transplants, as seeds are dust-fine. Annual, all zones. Height: 4–8 inches, trailing or mounded.

Blue Perennial Flowers for Long-Term Structure

Blue perennial flowers are the backbone of any permanent blue-themed garden. The fourteen below range from the dramatic height of delphiniums and agapanthus to the ground-hugging spread of brunnera and hardy geranium. Most perform best in well-drained, moderately fertile soil with at least six hours of sun — though brunnera and Jacob’s ladder actively prefer partial shade.

9. Delphinium (Delphinium elatum)

Delphinium is the most architecturally dramatic of all blue perennial flowers, producing towering spikes of densely packed blooms from pale sky blue to deep navy ‘Black Knight’. Heights range from 24 inches in dwarf Pacific Series to over 6 feet in tall strains. Plant in rich, well-drained soil with a slightly alkaline pH; stake tall cultivars early. Best in cool-summer climates — they struggle in the humid South. Zones 3–7. Cut back after the first flush for repeat bloom in late summer.

10. Catmint (Nepeta × faassenii)

Catmint is one of the most reliable and long-blooming blue perennials available, producing masses of lavender-blue flowers from late spring through frost when cut back hard after each flowering flush. ‘Walker’s Low’ grows 24–36 inches and is exceptionally drought-tolerant. Deer and rabbit resistant. It combines classically with roses, lavender, and salvia in cottage borders. Zones 4–8. Full sun to light shade. USDA Plant of the Year 2020. An ideal companion for bees and small butterflies.

11. Salvia nemorosa (Woodland Sage)

Salvia nemorosa varieties like ‘Caradonna’ and ‘May Night’ produce upright spikes of violet-blue flowers with prominent dark calyces that extend the visual season even after petals drop. Extremely drought-tolerant and deer resistant, thriving in lean, well-drained soil. Cut back by half after the first flush to encourage a second bloom in late summer. Zones 4–8. Height: 18–24 inches. Bumblebees and mason bees swarm the flowers throughout summer.

12. Spiked Speedwell (Veronica spicata)

Veronica spicata produces slender, tapering spikes of small blue flowers that attract butterflies and bees throughout summer. ‘Royal Candles’ is among the truest blue, growing 18–24 inches with a tidy upright habit that requires no staking. Deadhead spent spikes for continued flowering. Grow in full sun with good drainage; tolerates drought once established but resents winter wet. Zones 3–8. The closely related Veronicastrum virginicum (Culver’s Root) offers a taller, more structural alternative for the same zones.

13. Hardy Geranium ‘Rozanne’

Hardy geranium ‘Rozanne’ is one of the most celebrated recent perennial introductions — a Chelsea Flower Show Plant of the Centenary winner that produces large, clear violet-blue flowers with white centers from June until frost, with no deadheading required. The trailing habit (12–18 inches tall, 24-inch spread) makes it ideal for edging, ground cover, or weaving through border plantings. Sun to partial shade. Zones 5–8. Virtually pest-free and extremely long-lived in well-drained soil.

14. Blue Wild Indigo (Baptisia australis)

Baptisia australis is North America’s native alternative to lupins — a tough, long-lived perennial producing spikes of deep indigo-blue flowers in late spring above handsome grey-green foliage. Extremely drought-tolerant once established; plants thrive for decades with no attention. The deep taproot makes it transplant poorly, so place it carefully the first time. Zones 3–9. Height: 3–4 feet. Attractive inflated black seed pods follow the flowers and persist into winter as a structural element.

15. Blue Star (Amsonia tabernaemontana)

Amsonia’s soft periwinkle-blue flowers — small five-petaled stars in loose clusters — are gentler in color than most blue perennials, making it a superb blender rather than a focal point. The real asset is autumn foliage: the narrow willow-like leaves turn brilliant golden-yellow in fall, rivaling ornamental grasses in seasonal interest. Cut back by one-third after flowering to keep the plant compact. Zones 3–9. Height: 2–3 feet. Sun to partial shade. Native to the eastern US; extremely low-maintenance.

You might also find coral and peach flowers helpful here.

16. Balloon Flower (Platycodon grandiflorus)

Balloon flower gets its name from the distinctive balloon-like buds that inflate dramatically before opening into large, upward-facing star-shaped flowers. The most common color is clear sky blue, though pink and white forms exist. A long-lived, slow-spreading perennial; mark its location as it emerges late in spring and is easily damaged. Zones 3–9. Height: 12–24 inches. Thrives in well-drained soil with full to partial sun. Pairs beautifully with white gypsophila and silver artemisia.

You might also find red flowers for bold garden helpful here.

17. Italian Bugloss (Anchusa azurea)

Anchusa azurea ‘Loddon Royalist’ produces some of the deepest, richest gentian-blue flowers of any hardy perennial — a saturated true blue that photographs beautifully against silver or yellow foliage. Individual flowers are small but carried in clusters on branching stems 36–48 inches tall. A short-lived perennial that self-seeds to persist. Thrives in dry, chalky soils — excellent drainage is essential. Zones 3–8. A traditional cottage garden staple rarely seen in American gardens, which makes it an instant conversation piece.

You might also find pink flowers for romantic garden helpful here.

18. Siberian Bugloss (Brunnera macrophylla)

Brunnera macrophylla is the shade garden’s forget-me-not — producing identical tiny blue flowers on 12–18 inch stems in spring, but as a perennial that returns reliably each year. The large, heart-shaped leaves are the main reason to grow it: variegated forms like ‘Jack Frost’ have silver-frosted foliage that remains ornamental long after flowering. Tolerates dry shade once established. Zones 3–7. Deer resistant. Ideal under deciduous trees where spring sun reaches before leaf-out.

19. Agapanthus (African Lily)

Agapanthus produces globe-shaped flower heads packed with trumpet-shaped blooms in shades from pale sky blue to deep indigo, on stiff stems 18–48 inches tall. Deciduous forms are hardier (to Zone 6 with protection); evergreen forms are tender (Zones 9–10). ‘Headbourne Hybrids’ are among the most reliably cold-hardy. Full sun in well-drained soil; in colder zones, lift and overwinter dormant rhizomes. Often flowers more freely when slightly potbound in containers.

20. Ohio Spiderwort (Tradescantia ohiensis)

Tradescantia ohiensis is an underused native perennial producing three-petaled blue-purple flowers over a long season from early summer to fall if cut back hard after the first flush. The grass-like foliage wilts in drought but recovers quickly with rain. Zones 4–9. Height: 24–36 inches. Full sun to partial shade. Native to the eastern and central US; excellent for rain gardens and moist border edges. Attracts native bees including sweat bees throughout the growing season.

21. Jacob’s Ladder (Polemonium caeruleum)

Jacob’s ladder is named for its distinctive pinnate leaves arranged in a ladder-like pattern up the stems. The flowers are soft lavender-blue with contrasting yellow stamens, borne in loose clusters in late spring. ‘Brise d’Anjou’ offers cream-variegated foliage that extends the season of interest. Shade-tolerant and ideal under trees or in north-facing borders where most blue flowers fail. Zones 3–7. Height: 18–24 inches. Short-lived perennial that self-seeds reliably.

22. Monkshood (Aconitum carmichaelii)

Monkshood is one of the few perennials to bring blue-purple flowers to the late summer and fall garden, filling the color gap left by spent summer perennials. The deep indigo-blue, hooded flowers on upright stems 3–5 feet tall create dramatic vertical interest at the back of the border. Zones 3–7. Partial shade to full sun in cool climates. Important: all parts are highly toxic if ingested — keep away from children and pets, and wear gloves when handling. Deer resistant due to its toxicity.

Blue-Flowering Shrubs for Year-Round Structure

Blue-flowering shrubs provide structure and seasonal permanence that annuals and perennials cannot match. The five below range from the iconic mophead blooms of hydrangea to the late-season butterfly-attracting spikes of caryopteris, offering scale for every garden from a courtyard container to a large mixed border.

23. Mophead Hydrangea (Hydrangea macrophylla)

Blue mophead hydrangea is one of gardening’s most coveted blue flowers — but true blue is only achievable in acidic soil (pH 5.5 or lower). In alkaline soil, the same cultivar produces pink. Add sulfur or aluminum sulfate annually to maintain acidity. ‘Nikko Blue’ and ‘Endless Summer’ are among the most reliably blue cultivars. Zones 5–9. Height: 3–6 feet. For full care and soil pH management, see our complete hydrangea growing guide.

24. Bluebeard (Caryopteris × clandonensis)

Caryopteris is a low-maintenance, late-season shrub producing clusters of intensely blue flowers from late summer through fall — one of the last shrubs to bloom before frost. ‘Dark Knight’ offers the deepest blue. Cut hard to the ground in early spring; it flowers on new wood each year. Full sun, very well-drained soil; tolerates drought and poor soil once established. Zones 5–9. Height: 2–3 feet. Exceptional for wildlife: flowers attract migrating monarch butterflies and native bees in large numbers in September.

25. Leadwort (Ceratostigma plumbaginoides)

Ceratostigma plumbaginoides is a low-growing semi-woody perennial that produces vivid cobalt-blue flowers from late summer through fall, accompanied by foliage that simultaneously turns brilliant red — a dual-season display unlike anything else at that time of year. Height: 6–12 inches. Spreads slowly by runners to form a dense ground cover. Cut back in spring. Zones 5–9. One of the rare plants that combines blue flowers with dry shade tolerance once established.

They look similar but grow very differently — currant vs gooseberry explains.

26. Butterfly Bush (Buddleja davidii — blue-purple forms)

Buddleja’s ‘Blue Chip’ and ‘Nanho Blue’ produce elongated, honey-scented spikes in rich blue-purple from midsummer through fall. Deadhead immediately to encourage continuous blooming and reduce self-seeding. In many states standard buddleja is invasive — choose sterile dwarf varieties for responsible garden use. Zones 5–9. Height: 2–4 feet in dwarf forms. Full sun. An extraordinary butterfly resource: adult butterflies preferentially visit buddleja due to its high nectar concentration.

27. Chaste Tree (Vitex agnus-castus)

Vitex agnus-castus is an underused large shrub or small tree that produces lavender-blue flower spikes 6–18 inches long in mid to late summer — essentially a large-scale buddleja alternative better adapted to heat and drought. Spectacular in full bloom in July and August. Zones 6–9. Height: 8–15 feet if unpruned; cut to the ground in spring to maintain as a 4–6 foot shrub. Full sun. Tolerates drought, poor soil, and coastal conditions while attracting bees and butterflies prolifically.

Blue Spring and Summer Bulbs

Blue-flowering bulbs are some of the most reliable and low-effort plants in the garden. Spring bloomers emerge before most perennials stir, carpeting the ground with color while the rest of the border is bare. Summer bulbs extend the blue season into warm months and provide the vertical accents that ground-level plantings lack.

We put these side by side in summer squash vs winter squash.

28. Grape Hyacinth (Muscari armeniacum)

Muscari are the quintessential early-spring blue bulbs, producing dense spikes of tiny cobalt-blue, urn-shaped flowers from March through April. The most common species, Muscari armeniacum, naturalizes freely in lawns and under deciduous trees, spreading to form dense blue carpets over several years. Note that foliage emerges in fall — a quirk that matters for lawn management. Zones 3–9. Plant 3 inches deep and 3 inches apart in fall. Height: 4–8 inches.

29. Siberian Squill (Scilla siberica)

Siberian squill produces nodding, star-shaped flowers in a vivid, almost electric blue that is unlike any other spring bulb. It naturalizes aggressively — plant once and it spreads by self-seeding to carpet large areas within a few seasons. Works beautifully under deciduous trees where its early flowers come and go before the canopy leafs out. Zones 2–8. One of the hardiest spring bulbs available. Height: 4–6 inches. Flowers from March through April, often appearing through the last snow.

30. Camassia (Camassia leichtlinii)

Camassia is a majestic North American native bulb producing tall spikes of star-shaped flowers in deep blue to violet-blue during May and June, bridging the gap between spring tulips and summer perennials. ‘Blue Danube’ achieves a particularly rich blue. Naturalizes in moist meadow conditions; thrives in heavier soils than most bulbs. Zones 3–8. Height: 24–36 inches. Plant 4–6 inches deep in fall. An excellent choice for rain gardens and areas with seasonally moist soil.

31. Siberian Iris (Iris sibirica)

Siberian iris produces elegant, orchid-like flowers in violet-blue, purple, and white on slender, grass-like foliage. Unlike bearded irises, Siberian iris rarely suffers from iris borers or soft rot, making it one of the most trouble-free irises available. ‘Caesar’s Brother’ is a classic deep violet-blue; ‘Flight of Butterflies’ offers smaller, lighter blue flowers. Zones 3–9. Height: 24–36 inches. Prefers moist, slightly acidic soil. Thrives near ponds and rain garden edges.

32. Reticulated Iris (Iris reticulata)

Iris reticulata is a miniature bulbous iris that blooms in February and March — often among the first blue flowers of the year, pushing through snow or frozen ground. The small violet-blue flowers with a yellow signal are carried singly on stems just 4–6 inches tall. Plant in clusters for visible impact at the front of a border or in a rock garden. Zones 5–9. Plant 3–4 inches deep in fall. Needs dry summer dormancy to persist from year to year.

You might also find night scented flowers helpful here.

33. Glory-of-the-Snow (Chionodoxa luciliae)

Chionodoxa produces upward-facing blue flowers with white centers in early spring, often while snow still covers the ground. The species name references its habit of blooming at the snowline in its native Turkish mountains. Naturalizes freely under deciduous trees; combines beautifully with yellow narcissus or white snowdrops for a classic early spring combination. Zones 3–8. Height: 4–6 inches. Plant 3 inches deep in fall. Foliage disappears by early summer, making it an unobtrusive under-story bulb.

34. Spanish Bluebells (Hyacinthoides hispanica)

Spanish bluebells produce pendant, bell-shaped blue flowers in loose, upright spikes during April and May. They naturalize vigorously — in American gardens, they are simply reliable, blue-flowering bulbs that spread freely under trees and in partly shaded beds without any of the conservation concerns they pose in the UK. Zones 3–8. Height: 12–18 inches. Blue, pink, and white forms available. Mass planting under a flowering tree creates one of spring’s most spectacular combinations.

35. Blue Globe Onion (Allium caeruleum)

Allium caeruleum is the rare truly blue allium — while most ornamental onions produce purple or white blooms, this species produces tight, globe-shaped flower heads in a clear sky blue on thin, wiry stems 24 inches tall. Flowers in late May through June. Plant 3–4 inches deep in fall; naturalizes slowly. Zones 4–8. Full sun, well-drained soil essential. The spherical flower heads work beautifully among feathery ornamental grasses and silver-leaved plants in a modern, prairie-inspired planting scheme.

Designing with Blue Flowers

Creating a serene, blue-themed garden is as much about restraint as plant selection. A border filled entirely with blue flowers can read as monotonous; the most effective blue gardens use white, silver, and pale yellow as supporting tones that allow the blue to breathe and register fully against the surrounding landscape.

For a blue and white cottage border, try this three-tier structure: delphiniums as the tall vertical backdrop (4–6 feet), catmint and salvia nemorosa at mid-height (18–24 inches), and white sweet alyssum or lobelia at the edge. This combination provides color from May through October in most climates. For more space-saving planting strategies, see our 20 Small Garden Ideas, which includes several color-themed examples.

Blue flowers also have an outsized ecological value. True blue and blue-violet flowers — borage, phacelia, catmint, anchusa — are disproportionately important to native bees, which have evolved color vision tuned to the blue-violet end of the spectrum. A border rich in blue flowers is a genuinely wildlife-supportive choice, not just an aesthetic one. For a complete guide to building a pollinator-friendly habitat, see our Pollinator Garden Guide.

Finally, note that blue flowers look their most vivid in overcast light and in the early morning or evening. In intense midday sun, many blue blooms shift toward purple. Position key specimens — a catmint clump, a bluebell carpet — where you’ll view them at these cooler light conditions, and the calming quality that makes blue flowers so prized will be at its most powerful.

Frequently Asked Questions

Why is true blue so rare in flowers?

Plants produce blue through anthocyanin pigments, which naturally produce red or purple depending on the pH inside the petal cell vacuole. Achieving a true, unmodified blue requires specific acidic cellular conditions and often co-pigmentation with other flavonoids. Most ‘blue’ flowers are actually violet or blue-violet at a molecular level. True cerulean blue without any violet component — as seen in borage and cornflower — is genuinely rare and represents a specialized evolutionary adaptation.

Which blue flowers bloom the longest?

For continuous blue color, catmint (Nepeta) and salvia nemorosa are the champions among perennials, blooming from late spring through frost if cut back after each flush. Among annuals, blue lobelia and borage provide season-long color. For shrubby late-season blue, caryopteris blooms from August through October. Layering early (muscari, chionodoxa), mid-season (delphiniums, catmint), and late-season (caryopteris, monkshood) plants ensures blue in the garden from March through October.

Do blue flowers attract more pollinators?

Many native bees, including bumblebees and mason bees, see into the UV spectrum and have color vision tuned toward blue and violet wavelengths. Several studies have found blue and violet flowers receive more bee visits than red flowers (which are nearly invisible to bees) in mixed-color plantings. However, flower architecture and nectar reward matter as much as color — a richly rewarding orange flower will always outcompete a blue one with sparse nectar. Borage, phacelia, and catmint are blue flowers that deliver strongly on both color and nectar.

What are the easiest blue flowers to grow from seed?

Cornflower (Centaurea cyanus) and forget-me-not (Myosotis sylvatica) are the easiest blue flowers to start from seed — both are cool-season, direct-sow annuals that require no indoor starting and self-seed freely once established. Borage is another reliable option: large seeds germinate rapidly with no special preparation. For perennials from seed, baptisia and veronica spicata are straightforward, though baptisia takes 2–3 years to flower from seed.

How do I make hydrangeas turn blue?

Blue hydrangea color depends on soil pH, not variety alone. The same cultivar produces blue in acidic soil (pH 5.5 or below) and pink in alkaline soil (pH 7.0 or above). To turn pink hydrangeas blue, lower soil pH by incorporating elemental sulfur or aluminum sulfate in fall or early spring, and test your soil annually to maintain the target range. In areas with alkaline tap water, the soil gradually rebalances toward neutral — ongoing amendment is needed each year. For step-by-step guidance, see our hydrangea care guide.

References

1. NC State Extension Plant Toolbox. Centaurea cyanus (Cornflower). NC State University.
2. NC State Extension Plant Toolbox. Delphinium (Larkspur). NC State University.
3. NC State Extension Plant Toolbox. Baptisia australis (Blue Wild Indigo). NC State University.
4. NC State Extension Plant Toolbox. Nepeta x faassenii (Catmint). NC State University.
5. NC State Extension Plant Toolbox. Muscari armeniacum (Grape Hyacinth). NC State University.