Foxglove
Flowering spikes of foxglove, ranging from purple to white, glow in the darkest hollow of a woodland garden and shine in the back of a shaded bed. Because of its scale (up to 5 feet, sometimes higher) and its innate beauty, foxglove is an imposing flower, and one of the few that will bloom freely in deep shade. It is a biennial. establishing itself the first year and blooming in the late spring and summer of the second. Because it self-sows freely in a suitable spot, it may be considered a perennial—and, by some gardeners, a pretty pest.
The flowers are tubular, to 3 inches long, usually with spotted throats. Flowers of the species are pendulous and cover only one side of the stem. Those of one group of hybrids are dense, evenly distributed around the stem. and held straight outward.
The evergreen leaves are large, rough-textured ovals, dark green above, light green and fuzzy beneath. They are largest and most concentrated at the base of the plant. The leaves are poisonous to humans and animals if eaten. Digitalis, a medicinal drug, is derived from them.
Foxglove requires rich acid soil, moisture, good drainage, some degree of shade, and shelter from strong wind. Hybrids often adapt to less favorable soils. Space them 12 to 24 inches apart.
Stake plants if necessary. Cutting spikes severely after about half the flowers have finished will spur development of new spikes. Cutting them later may encourage second-year bloom. Snail bait, fungicide for powdery mildew, and insecticides for aphids, mealy-bugs, and Japanese beetles may be needed.
Hybrids of D. purpurea: Excelsior Hybrids produce dense, undrooping flowers all around the spikes. Colors are white and shades of mauve, pink, yellow, and rose. Height is 5 feet or more. Peak bloom is in June. Some gardeners consider this the choicest group of hybrids.
The slightly pendulous flowers of Foxy Hybrids begin at 18 inches and continue until the plants reach 3 feet.
Hyacinth Hybrids have 3-foot flower heads. Big flowers are mottled with red or brown.
Shirley Hybrids have 3-foot flower heads. Flowers are large and crowded. Many are dotted.
Related species and hybrids: D. grandiflora (D. ambigua) (Yellow Foxglove; Perennial Foxglove) is better considered a biennial than a perennial. In July its 3-foot spikes bear 2-inch pale yellow flowers with blotched throats. D. X ‘Mertonensis’ (Merton’s Foxglove) bears large, showy strawberry-colored flowers on 3 to 3/2- foot spikes in June and July.
