Stokesia laevis ‘Alba’

White Stoke’s Aster Asteraceae

Stokesia laevis ‘Alba’ is the rather elegant white-flowered form of Stokes’ aster, a North American perennial that has the useful habit of looking like a particularly well-bred cornflower while flowering considerably later than most of them. The flowers are large, frilly, thistle-like heads of pure white, carried on upright leafy stems above a handsome basal rosette of narrow, lance-shaped leaves. The effect is especially good in late summer, when the white flowers seem to glow above the darker foliage. The RHS lists it as flowering from summer into autumn. 

The species is native to the southeastern United States, from Alabama and Florida northwards through Georgia and the Carolinas and west to Louisiana and Texas, where it occurs in moist soils, wet pinewoods, savannas, bottomlands and similar open habitats. Despite this rather damp-sounding upbringing, it is surprisingly tolerant of drought once established; what it dislikes much more is cold, wet winter soil. 

Stokesia commemorates Jonathan Stokes (1755–1831), the English physician and botanist, while laevis means smooth, referring to the plant’s glabrous character. The species was originally described as Carthamus laevis by Philip Miller’s contemporary William Hill in 1768 and was transferred to Stokesia by Edward Lee Greene in 1893. The cultivar ‘Alba’ is simply the white-flowered form, rather than a separate species or botanical variety. 

A splendid plant for the front or middle of a sunny border, particularly where a long-lived perennial is wanted that is neither fussy nor inclined to disappear after flowering. It is also an excellent cut flower and useful for pollinators, with butterflies and bumblebees attracted to the summer flowers. 

Cultivation: Give it full sun and a fertile but very well-drained soil, preferably one that does not remain saturated in winter. It is happy in moisture-retentive soil during the growing season but winter drainage is critical. Deadheading encourages further flowers, and the foliage can be tidied in spring. The RHS rates it H4, hardy to around –10°C to –5°C, although established plants in excellent drainage can prove tougher. 

Height: 45–60 cm
Spread: 30–45 cm
Flowering period: July–September, sometimes later
Position: Full sun
Soil: Fertile, moisture-retentive but sharply drained
Hardiness: H4
Family: Asteraceae