Digitalis grandiflora aka Large Yellow Foxglove

Digitalis grandiflora is known as large yellow foxglove. It belongs to the Plantaginaceae family and forms leafy clumps. This perennial grows wild from central Europe to western Siberia. Its range also reaches Turkey, with plants in woods and along streams. Other habitats include mountain woods and dry, stony ground. It is not native to Britain or Ireland.

Garden plants reach about 2–3 feet [0.6–0.9 metres] tall. The RHS gives an upper height of 3.3 feet [1 metre]. Clumps can spread to about 1.6 feet [0.5 metres]. Upright stems rise above a basal rosette of green leaves. The leaves have fine teeth and an oval-to-lance-shaped outline. Lower leaves reach about 0.8 feet [0.25 metres] long. Leaves grow alternately along the stems and shrink toward their tips. The basal leaves remain green through winter, though some may suffer damage.

Soft yellow flowers hang from tall spikes above the leaves. Each flower forms a long tube with a flared mouth. Brown marks line the inside of the blooms. Flowers reach about 0.16 feet [0.05 metres] in length. The flower clusters can reach 1 foot [0.3 metres] long. The main bloom season runs from May to June. Removing faded spikes can prompt more flowers on side shoots. Spikes left in place may set seed and produce new plants.

Partial shade and soil rich in organic matter suit it best. It also tolerates sun and deeper shade in suitable soil. It grows in chalk, clay, loam, or sand. Acid, neutral, and alkaline soils can all support growth. Keep the soil moist, but allow excess water to drain. Avoid very dry ground and wet winter soil. Waterlogged soil can rot the crown and kill the plant. Its hardiness ratings are USDA zones 3–8 and RHS H6. Grow it from seed or divide clumps in early spring.

The flower spikes add height to borders and cottage gardens. They also suit open woodland gardens and naturalized areas. Dark shrubs or buildings help the pale flowers stand out. Deer tend to leave this plant alone. Serious pest and disease problems are uncommon, but damage can occur. Aphids, mealybugs, slugs, Japanese beetles, and eelworms may attack it. Mildews and leaf spots can spoil the leaves. All parts are poisonous, with risks to people and pets. It has no known edible uses. Sources record medicinal leaf use for heart complaints, despite its toxicity.