How to Prune small-flowered foxglove?
Cut back main flower spike as it fades to encourage the growth of flowering side shoots

small-flowered foxglove · Digitalis parviflora
Will grow in almost any soil or situation except very wet or very dry; ideal site is a humus-rich soil in partial shade. A perennial but often treated as a biennial.
Cut back main flower spike as it fades to encourage the growth of flowering side shoots