American Water Horehound (Americanus)

The American Water Horehound (Americanus) 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 summer and fall . The greatest bloom is usually observed in the early summer, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The American Water Horehound (Americanus) has a long life span relative to most other plant species and a moderate growth rate. At maturity, the typical American Water Horehound (Americanus) will reach up to 1.8 foot high, with a maximum height at 20 years of 0 inches.

The American Water Horehound (Americanus) is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by seed, tubers. 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 -38°F. has low tolerance to drought and restricted water conditions.

Plant Basics
Growth Rate Moderate
General Type Forb/herb
Growth Period Summer, Fall
Growth Duration Perennial
Lifespan Long
Plant Nativity Native to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Early Summer
Displays Fall Colors No
Shape/Growth Form Single Crown
Drought Tolerance Low
Shade Tolerance Tolerant
Height When Mature 1.8
Vegetative Spread None
Flower Color White
Flower Conspicuousness No
Fruit/Seed Abundance Medium
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Moderate
Gardening Characteristics
Propagations (Ways to Grow) Seed, Tubers
Moisture Requirements High
Cold Stratification Required No
Minimum Temperature -38
Soil Depth for Roots 10
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 5.2–7.8 pH
Precipitation Range 12–12 inches/yr
Planting Density 2700–10000 indiv./acre
Soil Textures Fine, Medium
Soil Depth for Roots 10
Minimum Frost-Free Days 120 day(s)
Salinity Tolerance Low
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Fire Resistant No
Causes Livestock Bloating None

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