Ageratina altissima is a robust native perennial known for its elegant white flower clusters that bloom in late summer and fall. Also known as White Snakeroot, this shade tolerant species thrives in woodland edges and naturalized borders, supporting native pollinators when few other plants are in flower. Its upright stems and toothed foliage provide a strong architectural presence through the growing season.
Height & Spread: 24 - 48 in x 18 - 36 in
Bloom Time: Late summer to fall
Light Requirements: Part shade to full shade
Soil Preference: Moist, rich, well drained soil
Watering Needs: Moderate
Deer Resistance: Resistant due to mildly toxic foliage
Native Status
Native to Eastern and Central North America, Ageratina altissima is commonly found in woodlands and along shaded slopes and ravines.
WILDLIFE & INSECTS
Bees
- Attracts small native bees such as sweat bees (Halictidae) and resin bees (Megachilidae) late in the season.
Butterflies
- Visited by fall flying butterflies including Painted Ladies, Pearl Crescents, and Red Admirals seeking late nectar.
Moths
- Supports nocturnal moth species including the Goldenrod Flower Moth and various Noctuids.
Birds
- Provides shelter at the base for small woodland birds such as thrushes and towhees especially in fall.
Spacing & Landscape Use
Spacing Recommendations:
- Allow 18 - 24 in spacing in drifts or as interplantings beneath open tree canopies.
Landscape Placement:
- Best suited for woodland borders, native plant gardens, or naturalized shade plantings.
Companion Plants
- Symphyotrichum cordifolium (Blue Wood Aster) - Offers airy lavender blooms that bloom alongside Ageratina, enhancing fall garden layers.
- Polygonatum biflorum (Solomons Seal) - Adds elegant arching foliage and spring flowers complementing Ageratina’s late season appeal.
- Solidago caesia (Blue Stemmed Goldenrod) - Yellow flowers and arching stems contrast well with Ageratina’s upright form and white flowers.
- Packera aurea (Golden Ragwort) - Provides spring color and creeping groundcover that naturalizes well with Ageratina.
- Carex pensylvanica - Native sedge with soft grassy foliage forms a textured carpet beneath taller Ageratina stems.