Pronounciation: Di-gi-TAL-is purr-purr-EE-a

Hardiness zones
Sunset All zones
USDA All zones

Landscape Use: Treated strictly as a cool season biennial in Phoenix, mixed mesic borders, nostalgic, herbal, and medicinal gardens, floral accent.

Form & Character: Upright, stout, festive, loud and boisterous, tender, wooly, vulnerable.

Growth Habit: Evergreen, herbaceous biennial, mostly densely rossetting the first growing season (fall/winter), bolting the second growing (late winter/spring) season to 3- to 6-feet tall (mostly on the shorter side in Phoenix).

Foliage/Texture: Tender, densely tomentose, gray green, ovate to 12-inches long and 5-inches wide, distinct, intricately netted, palmately compound veination, leaf margins subtly crenate; medium texture.

Flowers & Fruits: Terminal clusters of tubular, pendent flowers on an elongated bolting stalk, natural color is purple, but cultivated selections vary from pink, rose, yellow, to white, inside flower surface is heavily spotted; fruits are a capsule that open at maturity to release the numerous tiny seeds.

Seasonal Color: Flowers profusely during second growing season, which in Phoenix is during spring.

Temperature: Temperatures parameterizes the seasonal use of common foxglove in Phoenix in profound ways. On balance, it thrives in cooler weather with temperatures consistently below 85^oF and is a complete landscape wimp, fading quickly if temperatures exceed 95^oF.

Light: Full sun to partial sun, limit southwestern or western exposures.

Soil: Grows best in well-drained soils amended with composted organic matter. Intolerant of strongly alkaline soils.

Watering: Perfers regular "garden conditions", aka a rich, well-drained soil that is kept evenly moist. Thus, since common foxglove is a winter/spring biennial in Phoenix, the amounts and frequency of supplemental waterings will be dictated by the frequency of winter rains.

Pruning: None

Propagation: Seed

Disease and Pests: None

Additional comments: Common foxglove has a limited range of landscape uses in Phoenix due to the extreme summer desert heat. It is more commonly found in landscape gardens at cooler, higher elevations in Arizona, such as Prescott, Sedona, Payson, and Flagstaff. There are a myriad of cultivated selections, including the Camelot and Dalmatian series of selections. In Phoenix, common foxglove is often used as a landscape biennial interchangably with Hollyhock (Alcea rosea).

Biomedicinal factoids: All parts of common foxglove are toxic containing deslanoside, digitoxin, and digitalis glycoside, and if ingested can cause cardiac arrest, sometimes fatal. Therapuetic use of digoxin from leaf extracts are now used medicinally to inhibit the Na⁺/K⁺ ATPase pump in heart muscle cells causing an increase in intracellular Na⁺ that indirectly leads to an increase in Ca²⁺ ions stored in the sarcoplasmic reticulum. The increased calcium levels support a more forceful contraction of the heat muscle. The cardiac glycosides found in Digitalis are similar to those found in Nerium oleander.