Culture
Easily grown in average, medium moisture, well-drained soils in part shade. Prefers organically rich soils with consistent and regular moisture. Wet soils in winter can be fatal. Removal of flower spikes after bloom will encourage a secondary bloom. If flower spikes are left in place after flowering, plants may self-seed. However the spent flower spikes can rapidly become quite unsightly as the seed develops and many gardeners choose to remove most spikes and leave only a few for self-seeding. Once flowering and seeding is completed, cut back all stems to the basal foliage. Basal foliage is basically evergreen, but damaged leaves should be removed in early spring.
Noteworthy Characteristics
Digitalis grandiflora, commonly called yellow foxglove, is a clump-forming perennial that is native to woods and stream banks from central Europe to Turkey and Siberia. Large, tubular, funnel-shaped, pendulous, soft yellow flowers (to 2” long) with interior brown markings bloom in late spring to early summer in terminal racemes (to 12” long) atop upright leafy stems rising to 2-3’ tall. Finely-toothed, medium green, ovate-lanceolate leaves (to 10” long and 2” wide) appear in basal rosettes and alternately up the stems. Leaves in the basal rosettes are largest, becoming smaller as they rise up the stems. Individual flowers resemble the snipped-off fingers of a glove. Digitalis leaves are highly toxic to humans if ingested. Synonymous with Digitalis ambigua.
Genus name comes from the Latin digitus meaning "finger" for the flower shape.
Specific epithet is in reference to the large flowers of this species.
Problems
No serious insect or disease problems. Powdery mildew and leaf spot, if left untreated, can depreciate foliage considerably by early to mid-summer. Dense woody crowns may rot in soggy, poorly-drained winter soils. Potential insect pests include aphids, mealy bugs, slugs and Japanese beetle. Black spot may appear. Plants in the wild are becoming increasingly uncommon due to a combination of factors including habitat destruction and unlawful collection.
Uses
Flower spires provide architectural height to the border and cottage garden and are particularly effective in front of dark backgrounds such as provided by shrubs or buildings. Also appropriate for open woodland gardens and naturalized areas.