Foxglove

Digitalis purpurea

Medicinal Uses

Great care should be exercised in the use of this plant, the therapeutic dose is very close to the lethal dose.

The foxglove is a widely used herbal medicine with a recognised stimulatory effect upon the heart. It is also used in allopathic medicine in the treatment of heart complaints. It has a profound tonic effect upon a diseased heart, enabling the heart to beat more slowly, powerfully and regularly without requiring more oxygen. At the same time it stimulates the flow of urine which lowers the volume of the blood and lessens the load on the heart. The plant contains cardiac glycosides (including digoxin, digitoxin and lanatosides). Digitoxin rapidly strengthens the heartbeat but is excreted very slowly. Digoxin is therefore preferred as a long-term medication. The leaves are cardiac, diuretic, stimulant and tonic. The leaves should only be harvested from plants in their second year of growth, picked when the flowering spike has grown and about two thirds of the flowers have opened. Harvested at other times, there is less of the medically active alkaloid present. The seed has also been used in the past. The leaves also have a very beneficial effect on the kidneys, they are strongly diuretic and are used with benefit in the treatment of dropsy.

Other Uses

Dye, preservative.

An infusion of the plant prolongs the life of cut flowers. Root crops growing near this plant store better. An apple-green dye is obtained from the flowers.

Cultivation details

Easily grown in ordinary garden soil, especially if it is rich in organic matter. Prefers a light dry soil in semi-shade but succeeds in full sun if the soil is moist. Grows well in acid soils. Plants are hardy to about -25°c. The foxglove is a very ornamental plant that is easily naturalized in the semi-shade of a woodland. It contains glycosides and forms the basis of an important heart medicine for which it is cultivated commercially. This species is commonly used by herbalists, whereas D. lanata is more commonly grown for supplying the pharmaceutical industry. The plant contains much greater concentrations of the medically active ingredients when it is grown in a sunny position. The flowers are very attractive to bees. Individual plants can produce up to 2 million seeds. Members of this genus are rarely if ever troubled by browsing deer or rabbits. A good companion plant, it stimulates the growth of nearby plants, growing well with pine trees.

Propagation

Seed - surface sow early spring in a cold frame. The seed usually germinates in 2 - 4 weeks at 20°c. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. If you have sufficient seed it can be sown outdoors in situ in the spring or autumn.