By Jim Lakin, MD, Master Gardener
A beautiful Nineteenth Century sketch of Digitalis purpurea]
In the year 1785 the English physician William Withering published An Account of the Foxglove, describing the medicinal features of extracts of this native perennial in the treatment of dropsy. That was a term for the swelling associated with severe congestive heart failure. This was the first account of its use in the medical profession, yet herbalists had been using foxglove tea to treat heart failure for centuries before. The only drawback of this “miracle cure” was that too much of a good thing could quickly dispatch the tea imbiber. The pharmacologically active agent in foxglove is digitalis, a drug still used today to treat heart failure and disturbances of heart rhythm. Digitalis, like foxglove has a narrow therapeutic range. Too much can cause serious side effects, including death. If, however, you are not prone to munching on your garden perennials, you will find that Digitalis purpurea is a charming addition to your landscape.
Although originally native to most of Northern Europe, it has naturalized to the Upper Midwest where it grows as an herbaceous biennial or short-lived perennial. That is to say, a given plant usually lives two to three years but plentifully reseeds. Thus, if a garden area is left undisturbed, germination should provide an ongoing colony of Foxglove. In the first year, the plant forms a tight rosette on the ground. The second year a 3 to 6 foot stem develops with spirally arranged 3 x 2 inch or larger leaves. The flowers are arranged in a showy, terminal, elongated cluster. Each flower is tubular hanging downward. The “finger like” flower shape is reflected in the name Digitalis. These flowers are typically purple, but some plants, especially cultivars, of which there are many, may be pink, rose, yellow, or white. Foxglove tends to bloom in late spring to early summer with occasional shows later in the season.
Digitalis purpurea prefers partial sunlight to deep shade, being a forest understory dweller. It frequently pops up in areas where the soil has been recently disturbed. Some accounts maintain that skin contact with foxglove can be harmful, so it is best to wear gloves when handling it. Although it can be grown from seed, this can be a little tricky and germination rates are not all that high. It’s probably a better bet to purchase a potted plant in the spring and enjoy the spectacular show that Foxglove provides. And remember, no nibbling the plants!