Glaucus Willowherb (Glaberrimum)

The Glaucus Willowherb (Glaberrimum) is generally described as a perennial forb/herb. This is native to the U.S. (United States) has its most active growth period in the spring and summer . The greatest bloom is usually observed in the mid summer, with fruit and seed production starting in the summer and continuing until summer. Leaves are not retained year to year. The Glaucus Willowherb (Glaberrimum) has a moderate life span relative to most other plant species and a slow growth rate. At maturity, the typical Glaucus Willowherb (Glaberrimum) will reach up to 2 feet high, with a maximum height at 20 years of 2 feet.

The Glaucus Willowherb (Glaberrimum) is not commonly available from nurseries, garden stores and other plant dealers and distributors. It can be propagated by seed. It has a moderate ability to spread through seed production and the seedlings have medium vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -8°F. has low tolerance to drought and restricted water conditions.

Plant Basics
Growth Rate Slow
General Type Forb/herb
Growth Period Spring, Summer
Growth Duration Perennial
Lifespan Moderate
Plant Nativity Native to U.S.
Commercial Availability No Known Source
Physical Characteristics
Bloom Period Mid Summer
Displays Fall Colors No
Shape/Growth Form Rhizomatous
Drought Tolerance Low
Shade Tolerance Tolerant
Height When Mature 2
Vegetative Spread Slow
Flower Color Purple
Flower Conspicuousness No
Fruit/Seed Abundance High
Fruit/Seed Seasonality Summer Summer
Seed Spread Rate Moderate
Gardening Characteristics
Propagations (Ways to Grow) Seed
Moisture Requirements Medium
Cold Stratification Required No
Minimum Temperature -8
Soil Depth for Roots 8
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Slow
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 6.1–7.5 pH
Precipitation Range 12–12 inches/yr
Planting Density 0–0 indiv./acre
Soil Textures Fine, Medium
Soil Depth for Roots 8
Minimum Frost-Free Days 200 day(s)
Salinity Tolerance None
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Palatability Low
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database,
National Plant Data Center, Baton Rouge, LA 70874-4490 USA