Masses of Digitalis purpurea, or common foxgloves, put on a stunning show with their tall stalks of flowers, but there are some things designers should know. Primarily for landscape architects, specifying D. purpurea should be addressed similarly to the use of annuals, as gardeners do with D. purpurea 'Foxy.' Here in California, they behave as biennials, where they will grow beautiful rosettes of foliage the first year followed by blooming the second. Afterwards, most will die, but some may live on if one is lucky. This short lifespan means the species is reliant on reseeding, which it will readily do in the right conditions.
The California Invasive Plant Council identifies common foxgloves with limited invasiveness. This means that you will see them in natural areas from California throughout the Pacific Northwest, particularly along roadsides. They have minimal impact; while they do indeed spread, D. purpurea does not pose much of a threat for native species at this time.
Where they can be harmful is in gardens and landscapes where unaware humans and animals might sample the toxic leaves. This is something to take seriously when considering their inclusions in gardens with pets, children, and/or the general public.
facts
Botanical Name: Digitalis purpurea
Digitalis: Latin, digitus for finger, but the reference might be derived from German's fingerhut (pronounced fingerhoot) for thimble. The flower's resemblance.
Purpurea: Purple
Common Name: Common foxglove
Family Name: Plantaginaceae
Origin: Southern Europe, Mediterranean
design considerations
Positioning: Foreground, middle ground, vertical spaces
Garden Themes: Perennial, woodland, bedding, naturalized, pollinator, cottage/informal, rock, cutting, coastal, courtyard, patio
Uses: Border, mass, cut flower (wear gloves), embankments, containers
identifying characteristics
Type: Herbaceous perennial (biennial/annual)
Form: Clumping, erect when in bloom
Texture: Coarse
Size: 2' tall and wide; up to 5' when in bloom (cultivars vary)
Outstanding Feature(s): Flower
Stems: Light green, pubescent
Leaf:
Type: Simple
Arrangement: Rosulate
Shape: Ovate, lanceolate
Margin: Crenate
Color: Light green
Surface: Quilted appearance, slightly tomentose
Flower: Spring to summer. Tubular flowers, raceme on tall stalks, color range white/cream, purple, pink (vary by cultivars). Showy
Fruit: Summer. Brown capsules follow flowers on stalks. May easily reseed in the right conditions.
cultural requirements, tolerances & problems
Sunset Zones: A2, A3; 1-24
USDA Zones: 4-8
Light: Sun in cooler regions to partial shade inland
WUCOLS SF Bay Area Hydro Zone: Moderate
Soil:
Texture: Loam, well composted
Moisture Retention: Even moisture
pH: Acidic
Tolerances: Deer, rabbit
Problems: Limited invasiveness, slugs, high toxicity in leaves for humans and animals
Branch Strength: Weak
Insects: Japanese beetles, aphids, mealy bugs
Disease: Powdery mildew, leaf spot, rot
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Extension Gardener. "Digitalis purpurea." North Carolina State University Extension, Raleigh. Accessed on August 8, 2021, from https://plants.ces.ncsu.edu/plants/digitalis-purpurea/.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
Plant Finder. "Digitalis purpurea." Missouri Botanical Garden, St. Louis. Accessed on August 8, 2021, from http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c530.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on July 27, 2021.
Photos:
Detail photo purchased from Shutterstock.