Foxglove

About Foxglove

Common foxglove is a cottage-garden classic. The first year it makes a low rosette of soft, veined leaves; the second year it sends up 2-5 ft spikes of tube-shaped flowers, often spotted inside, that bumblebees and hummingbirds visit (NC State, Wisconsin Extension). Every part is deadly poisonous: it contains the heart compounds behind digitalis medicines, and its first-year leaves have been mistaken for comfrey, borage and even kale (CMAJ, Poison Control). It reseeds heavily, and California's Cal-IPC lists it as an invasive plant.

Hardy in zones 4-9, though some cultivars only to zone 5 (Wisconsin Extension). Invasive: Cal-IPC rates it a 'Limited' invasive in California meadows and roadsides, and Wisconsin Extension notes it's weedy in the Pacific Northwest; a different species, Grecian foxglove (D. lanata), is a prohibited noxious weed in Minnesota.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Sow seed outdoors in late summer for flowers next year, or indoors in late spring; don't cover the seed, since it needs light to sprout (Wisconsin Extension). Move seedlings out after the last spring frost, about 18 inches apart. Most plants bloom their second year, but 'Foxy', 'Camelot' and 'Dalmatian' flower the year they're sown. We found no sourced day count to first bloom, so days_to_harvest is empty.

Soil

Moist, well-drained soil high in organic matter, on the acid side (below pH 6.0); it does best with afternoon shade, and dry spells cut flowering (NC State, Wisconsin Extension).

Work compost or other organic matter into the bed so the soil stays moist and humus-rich; foxglove likes slightly acid soil (NC State).

Feeding

• Early spring of the blooming year, just before new growth starts: complete slow-release fertilizer such as 12-6-6. Without a soil test, Clemson suggests 1-2 lb per 100 sq ft; keep it off the leaves and water it in.

Too much fertilizer gives soft growth and fewer flowers (Penn State). Don't let the soil dry out, and wear gloves when handling the leaves.

Harvest

The main show is early summer of the second year; cutting off spent spikes can bring a few more stems later (Wisconsin Extension). Deadhead to limit seedlings, but leave a few spikes to drop seed if you want foxgloves every year. For the vase, cut when about half the flowers on the spike are open (Oklahoma State). Wear gloves: the leaves can irritate sensitive skin.

Varieties (12)

Wisconsin Extension and NC State document these 12 foxgloves; we found no other trustworthy cultivar lists.

Pests to watch for

Aphids, Japanese beetle, Mealybugs

Diseases and problems

Powdery mildew, Fungal leaf diseases

In the kitchen

Safety: Deadly poisonous. Every part contains cardiac glycosides (digitalis) that can cause vomiting, severe headache, blurred or colored vision, a slow or irregular heartbeat and death (NC State, MedlinePlus). The first-year leaf rosette has been mistaken for comfrey and borage leaves, and in one Canadian case for kale, causing serious poisonings (CMAJ, Poison Control). Never make tea or food from it; if any is swallowed, call Poison Help at 1-800-222-1222.

Pets: Toxic to dogs, cats and horses (ASPCA). Its heart-affecting glycosides are in every part (NC State), and Poison Control advises not planting it where pets play.