My notion of the perfect flower garden was formed early in life. I took it directly from a fanciful illustration of an English cottage garden in my nursery-rhyme book.  I recall being enchanted by the towering spires of blue blooms—probably delphiniums, but possibly ladybells—before which Mistress Mary flounced contrarily down her garden path.

In reality, stately plants bearing slender inflorescences of blue do lend grace, romance, and repose to a garden and provide counterpoint to frothy phloxes, puffy alliums, dotty daisies, and misty grasses.  I’ve found I can grow a season-long succession of spiky blue flowers, most of which return year after year. 

Spring Blues

First come the camassias, from late March into May.  Most effective in mass, our eastern native wild hyacinth (Camassia scilloides; USDA Zones 3–9) slowly unfurls a tapering raceme of pale blue starlike flowers atop a sturdy two- to three-foot stem. Camassias grow from bulbs and do well in sun or light shade in consistently moist soil that drains but not quickly.  They vanish into dormancy as soon as seed is set. Selections of the western North American species C. leichtlinii subsp. suksdorfii (Zones 4–8)offer blooms of a deep violet blue that contrasts smartly with their own vivid yellow anthers.

We may think of Spanish bluebells (Hyacinthoides hispanica; Zones 3–8) as short and squat, but the periwinkle blue–flowered ‘Excelsior’ can grow to 20 inches or more, with a stiffly regal bearing. The exquisitely shaped bells cling to a scape that emerges from a clump of fleshy straplike leaves, which wither shortly after the March and April bloom.  The bulbs remain busy underground, increasing with rabbitlike fecundity to produce a showier spectacle every year.  Spanish bluebell thrives in sun or shade and in almost any soil.

Blue false indigo (Baptisia australis; Zones 3–9) blooms for a couple of weeks from late April into May, with lupinlike spires of blue pea flowers. After blooming, the shrub makes an attractive silver-blue background for summer- and fall-flowering annuals and perennials.  The drought-resistant, sun-loving long-lived false indigo is easy to grow in most well-drained soils.

Now, the fancy hybrid delphiniums are as rare as icebergs in my sultry Alabama climate.  If the heat doesn’t get ’em, the slugs will.  But I’d love to see breeders do more with our eastern and central United States native species, such as the willowy Delphinium exaltatum (Zones 5–7), which displays six-foot racemes of long-spurred, gentian blue flowers; the similarly statuesque D. carolinianum (Zones 5–8); and the delightfully unfussy two-foot D. tricorne (Zones 4–8), a colorful habitué of woodlands and prairies.

The delphinium’s hardy annual cousin larkspur (Consolida spp.) is more common in gardens here, coming into bloom the latter part of April and carrying on for eight weeks or more. For sheer blueness I adore the four- to five-foot C. ajacis ‘Sublime Azure Blue’, a double-flowered strain with spires of a chilly soft blue. Some gardeners brag that larkspur self-sows to peskiness in their gardens, but for me it dwindles over time unless I’m careful to save and sow the seed (in fall for bloom the next spring).

Summer Blues

It’s a pity our many native skullcaps (Scutellaria spp.) are strangers to most gardens. In May and June, pointy upright panicles of luminous lavender blue blossoms appear among the scalloped fuzzy leaves of heartleaf skullcap (S. ovata; Zones 4–8), a charming rhizomatous woodland mint. 

I recently discovered on the Internet that there are numerous spectacular ladybells (Adenophora spp.) to be had.  Alas, I grow only common ladybells  (A. confusa; Zones 3–8), so botanically named, I suspect, because it is readily confusaed with the gorgeous but universally maligned (for invasiveness) Campanula rapunculoides.  From late May into July, common ladybells sends up three-foot spires of medium blue bells.  Lilyleaf ladybells (A. liliifolia; Zones 3–8), with flaring bells of lavender-blue, is similar but, at 18 inches, less imposing.  Ladybells thrives (to excess, according to sources in cooler climates than mine) in sun or light shade in consistently moist but well-drained soil.   

American bellflower (Campanula americana; Zones 4–8) comes into bloom in late June.  This seldom-seen hardy annual or biennial, common to woodlands throughout most of the eastern and central states, belongs in more gardens.  The one- to six-foot often branching stems are clothed with curvy tapered leaves and tipped with spears of starlike periwinkle blue flowers.  American bellflower does best in moist soil in partial sun or light shade.

Autumn Blues

By the time the bellflower fades in August, great blue lobelia (Lobelia siphilitica; Zones 4–9) is coming into a long season of glory, presenting densely packed, two- to three-foot racemes of pleated tubular flowers of a rich purplish blue.  Though it is found in wet areas across the eastern two-thirds of the country, great blue lobelia is robust and reliable in the average garden, sun or shade, as long as it receives regular water.

One could conceivably enjoy spring-to-fall spires of blue with salvias alone. Silvery blue mealy-cup sage (Salvia farinacea; Zones 8–10) blooms nonstop from spring to frost, so it makes a first-rate bedding plant even where it isn’t winter hardy.  Salvia guaranitica (Zones 8–10) is a summer-to-fall bloomer, often surviving our Zone 7 winters in a well-drained protected site. My favorite summer-to-frost salvia is the sprawling sterile hybrid S. ‘Indigo Spires’ (Zones 7– or 8–11).  It’s fun to watch the bumblebees bouncing on the long looping spikes of iridescent violet-blue flowers. Cultivars or hybrids of S. nemorosa (Zones 4–8) provide similarly vivid color on more rigid spikes. With regular deadheading, the long-popular cultivar East Friesland (S. n. ‘Ostfriesland’) and the slightly taller ‘Caradonna’ will hoist up dark purple stems densely studded with blue-violet flowers from spring until fall.  And our native blue sage (S. azurea var. grandiflora; Zones 5–9) blooms from midsummer to October with flowers as blue as that month’s clear sky.

Blues’ backup

Here are the plants that flower in concert and complement with Carol Bishop Miller’s succession of blue blooms.

Months	Blue-flowering plant	Companions
March to May	Camassia scilloides	foamflower, Piedmont azalea
March and April	Hyacinthoides hispanica	pink azaleas, such as ‘Pink Dawn’
April into May	Baptisia australis	pink peonies, yellow bearded irises
April to July	Consolida ambigua ‘Sublime Azure Blue’	‘Blue Diadem’ bachelor’s buttons
May and June	Scutellaria ovata	lamb’s ears, rose campion
May into July	Adenophora confusa	hollyhocks, Penstemon digitalis ‘Husker Red’
June into August	Campanulastruamericanum	pink summer phlox, purple coneflower
August into October	Lobelia siphilitica	black-eyed Susans, pink asters, Japanese anenomes, and mums

Web Extra: More blue-flowering plants

Monkshood (Aconitum carmichaelii; Zones 3–7; to 6 feet). Narrow panicles of purplish blue, helmet-shaped flowers August-September. Consistently moist, wel-drained, rich soil; partial shade. Dislikes hot, dry climates. Poisonous.

Blue Fortune anise hyssop (Agastache ‘Blue Fortune’; Zones 5–9; 18 inches). Spikes of lavender-blue flowers in summer. Sun and well-drained soil.

Lochinch butterfly bush (Buddleia x‘Lochinch’; Zones 6–8; 6 feet).  Silver-leaved shrub with conelike panicles of lavender-blue flowers in summer. Deadhead to prolong bloom.  Sun, good drainage.

Grosso lavander (Lavandula xintermedia ‘Grosso’; Zones 5–8; to 4 feet). Blue-green foliage capped in summer by chubby spikes of blue-violet flowers. Intensely aromatic. Sun, sharp drainage.

Six Hills Giant catmint (Nepeta xfaassenii ‘Six Hills Giant’; Zones 4–8; to 4 feet).  Spikes of violet-blue flowers spring to frost if deadheaded. Aromatic. Sun to part shade, well-drained soil.

Foothill penstemon (Penstemon heterophyllus; Zones 6–9; to 3 feet). Racemes of intense violet-blue trumpet flowers in late spring. Deadhead for repeat bloom. Sun or part shade, sharp drainage, moderate water.

Blue Spire russian sage (Perovskia atriplicifolia ‘Blue Spire’; Zones 5–9; to 4 feet).  Lavender-blue summer-to-fall flowers; deeply cut, aromatic, gray-green foliage.  Sun, moderate water, sharp drainage.

High Five Speedwell (Veronica spicata ‘High Five’; Zones 4–8; to 3 feet).  Spears of violet-blue flowers in summer.  Sun, part shade; average moisture; sharp drainage.

Chaste tree (Vitex agnus-castus; Zones 6–9; to 15 feet).  Shrub or small tree with palmate leaves and pointy panicles of lavender-blue summer flowers.  Grown as herbaceous perennial in North.  Great with pink crape myrtle. Sun, average moisture, good drain