Cardamine douglassii
purple cress
Overview
Cardamine douglassii is a small spring-ephemeral perennial in the mustard family, growing 4-12 in (10-30 cm) tall from a slender rhizome. Rounded to heart-shaped basal leaves on long stalks rise in early spring, with smaller, often purple-tinged leaves along the flowering stems. The stems carry loose clusters of four-petaled flowers, each 0.4-0.6 in (1-1.5 cm) across, in shades of pink to pale purple, sometimes nearly white. It flowers early in spring, often before the surrounding tree canopy leafs out. The species is native to eastern North America, growing in moist, rich deciduous woods, floodplains, and along streams, frequently on limestone-influenced soils. It grows in USDA zones 4 to 8 and goes dormant by early summer after setting seed. It needs spring moisture and cool, shaded conditions; it does not tolerate hot, dry, sunny sites and disappears entirely during summer dormancy.
Native Range
Cardamine douglassii is native to eastern North America, from southern Ontario and the northeastern United States west to Wisconsin and south to the southeastern states. It grows in moist, rich deciduous woods, floodplains, and streambanks, often on calcareous soils.Suggested Uses
Used in woodland and native spring gardens alongside other ephemerals, spaced 6-10 in (15-25 cm) apart, where it can go dormant undisturbed in summer. The early flowers supply nectar and pollen for emerging bees.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread4" - 8"
Reaches mature size in approximately 3 years
Bloom Information
Flowering occurs in early to mid spring, generally March to May, often before the tree canopy leafs out. The pink to purple flowers open over 2-4 weeks. The plant sets seed and goes dormant by early summer.
Detailed Descriptions
Flower Description
pink to pale purpleFoliage Description
green, often purple-tingedGrowing Conditions
Sun Requirements
Requires 2-4 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Cardamine douglassii grows in part shade to full shade and moist, rich, well-drained soils high in organic matter, with pH from 6.0 to 7.5. It is hardy in USDA zones 4 through 8 and grows during the cool, moist conditions of early spring before going dormant in summer. Water needs are moderate in spring and low once dormant. It spreads slowly by rhizome and seed to form small colonies. Hot, dry, or sunny sites cause early dieback and poor persistence.Pruning
Leave the foliage in place until it yellows and dies back after flowering, as it nourishes the rhizome for the next season. No structural pruning is needed for this small spring ephemeral. Seed can be left to ripen for natural spread.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
late spring
Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons