White Snakeroot (Ageratina altissima)

White Snakeroot

Ageratina altissima

Ageratina altissima, commonly known as White Snakeroot, is a perennial herb that grows between 1 to 4 feet tall. It features broad, serrated leaves and clusters of small, white flowers that bloom from late summer to fall. This plant is typically found in woodlands and shaded areas with rich, moist soils. Historically, it was believed to have medicinal properties, but all parts of the plant are highly toxic to livestock and humans if ingested, leading to severe symptoms such as vomiting and cardiac damage. In landscaping, White Snakeroot can be used in shaded gardens for late-season blooms.

Characteristics

Type	Forb
Sun	Partial Sun, Shade
Soil	Clay, Loam
Moisture	Mesic
Average Max Height (inches)	36
Suggested Plant Spacing (inches)	30
Bloom month(s)	July, August, September, October
Bloom Color or Type	White
Dominance	Low

Range Maps

Sowing Information

Sow seed onto a firm, weed-free seedbed. Hand-broadcast seed making two perpendicular passes for even coverage. If planting a mix, broadcast the grass component first and lightly rake/drag it into the top 1/8–1/4" of soil. Next, broadcast wildflower/forb seed and press it into the soil surface (with a roller/cultipacker or the back of a rake) to ensure good seed-to-soil contact. After seeding, apply a very light layer of clean, seed-free straw (or other weed-free, site-appropriate mulch) to reduce erosion and retain moisture without smothering seedlings. A good rainfall or thorough watering will help settle seed and mulch and improve germination.

Planting Information

Dig a hole in your planting site slightly larger than the plant’s root system. When placing the plant into the hole, ensure that the soil line remains consistent with its original level in the pot. Fill in around the roots with the excavated soil, gently firming it to eliminate air pockets. Water the plant thoroughly the same day to promote successful establishment.