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Ageratina altissima

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Ageratina altissima

Common Name: White Snakeroot

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

For most homeowners, the recommended method is to hand-broadcast seed at a minimum rate of 16–64 PLS (Pure Live Seed) ounces per acre. To ensure even coverage, broadcast the seed in perpendicular passes across the site. Grass seed should be broadcast first and lightly raked into the soil. Afterward, apply a light mulch layer using clean, seed-free straw or, preferably, our native Little Bluestem straw, available at our retail garden centers. Once mulching is complete, broadcast native wildflower seed over the area without raking it in. A good rainfall or thorough watering will provide sufficient soil contact for successful 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.

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