Native to parts of Europe and Africa, this striking member of the plantain family is naturalized throughout North and Central America. Both the common name foxglove and the genus name Digitalis refer to the tubular shape of the plant’s flowers, which appear to fit over the fingers like a glove. Digitalis derives from the Latin digitus, meaning finger. Although all parts of the plant are extremely poisonous, foxglove has been cultivated for medicinal use for more than 1,000 years.
The 16th-century English herbalist John Gerard recommended boiling foxglove in water or wine for use as an expectorant. The herb’s main use, for treating a weak heart, was not described until 1785, when English physician and botanist William Withering (1741–1799) published An Account of the Foxglove and Some of Its Medicinal Uses.
Common Names: Digitalis, Foxglove, Purple Foxglove
Description: Produces rosettes of downy leaves in its first year; spikes of 2- to 3-inch pink, purple, or white bell-shaped flowers follow in the second year; flower stalks up to 6 feet tall
Hardiness: Biennial; to Zone 4
Flowering: Late spring to midsummer
Parts Used: Leaves and flowers
Range/Habitat: Native to the Mediterranean region and Europe; woodland clearings and mountain slopes
Foxglove, a diuretic, contains cardiac glycosides that have been used in traditional and modern medicine to increase the force of the heart’s contractions. In the past, the herb was taken in leaf form to treat irregular heartbeat and heart failure. Foxglove is still the source of the widely used pharmaceutical drugs digoxin and digitoxin—important therapies for heart disease—but the plant’s leaves are no longer used because the correct dosage is hard to determine. In several cases, ingesting this powerful plant has resulted in death. In one, a closely related species was mistakenly added to a commercially sold internal herbal cleansing product, leading to cardiac arrest and death; apparently it was believed to be plantain leaf. In other cases, people harvest foxglove (confusing it with comfrey or another plant), use it as a tea, and become seriously ill.
Caution: Foxglove is extremely toxic and should never be ingested.
Gardeners love foxglove for its beauty. Its tall bloom spikes add early summer color to cottage gardens and mixed perennial borders, and the plants naturalize readily at woodland edges. Select tall cultivars, such as pink ‘Giant Shirley’ or rose-pink ‘Candy Mountain’, for a dramatic display in front of a stone wall, hedge, or fence. Foxglove combines well with goat’s beard (Aruncus dioicus), bugbanes (Actaea spp.), and yuccas (Yucca spp.).
Foxglove is sometimes used as a dye. When mordanted with alum, the flowers produce a chartreuse color.
How to grow it
Foxglove grows in moist, humus-rich soil in full sun or partial shade. Sow seeds indoors in seedling trays in late winter, then transplant the seedlings to the garden after the danger of frost has passed. Seeds can also be sown directly in your garden in late summer. Plants generally bloom the second year. Once established, foxglove needs little attention and will self-seed readily. For a more tidy look, lift the plants after they have finished flowering, remove the faded bloom stalks, and replant the remaining rosettes for next year’s bloom.
From an English Garden to the World’s Pharmacy
In 1775, the English physician and botanist William Withering (1741–1799) was asked to evaluate a folk cure for “dropsy,” an ancient name for the swelling caused by an accumulation of fluid (edema) in body cavities or under the skin. This condition produces the characteristic swollen ankles now known to be the result of congestive heart failure, which results when that organ can no longer pump enough blood throughout the body.
Withering found an herbal mixture used by a person he described as “an old woman in Shropshire, who had sometimes made cures after the more regular practitioners had failed.” He identified more than 20 different herbs in her mixture and determined that foxglove was the “active herb.” Withering then used foxglove to treat his patients with dropsy and observed that the herb controlled heartbeat in a different way than other medicines did.
Over time, and with some failures, his experiments resulted in more standardized foxglove extracts that successfully healed a high percentage of his patients. One contemporary evaluation of his therapies and their results suggested a success rate of 65- to 80 percent! It is remarkable that the plant used by the “old woman in Shropshire” has been, in its various forms, a first-line therapy for centuries. Sometimes, Grandmother knows best.