These spring-blooming bulbs were once classed in the genus Scilla and are still popularly known by that name; some bulb dealers continue to list them as such. They resemble hyacinths but are taller, with looser flower clusters and fewer, narrower leaves. Spanish bluebell (H. hispanica) is the preferred choice for most Southern gardens. English bluebell (H. non-scripta) definitely prefers colder winters and moderate to cool summers. When grown near each other, the two species sometimes hybridize, producing intermediate forms.
H. hispanica. SPANISH BLUEBELL. Zones US, MS, LS, CS; USDA 6-9. From Spain, North Africa. Prolific and vigorous, with inch-wide, strap-shaped leaves and sturdy, 20-in. stems bearing 12 or more nodding, unscented bells about 34 in. long. Blue is the most popular color, 'Excelsior' (deep blue) the most popular selection. There are also white, pink, and rose forms. Leaves can look a trifle ratty before dying back.
H. non-scripta. ENGLISH BLUEBELL, WOOD HYACINTH. Best in Zones US, MS; USDA 6-7. From western Europe. Fragrant, blue flowers are narrower and smaller than those of H. hispanica, on 1-ft. stems that nod at the tip and carry their flowers on only one side. Leaves are also narroweronly about 12 in. wide. 'Alba' is white flowered; 'Rosea' has pink blooms.
Plant bulbs in fall, setting them 3 in. deep in mild climates, as deep as 6 in. where winters are severe. Space about 6 in. apart. Propensity for reseeding makes these good subjects for naturalizing; lovely in informal drifts among tall shrubs, under deciduous trees, among low-growing perennials. Need regular moisture from planting time until foliage dies and at least some moisture in summer. Divide infrequently; when division is needed, do it in late spring or early summer, when the leaves yellow. Plants thrive in pots, and flowers are good for cutting. Bulbs can cause allergic reactions on contact. Not favored by browsing deer.