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Ageratina altissima (White Snakeroot)

Ageratina altissima (White Snakeroot)

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Regular price $ 22.67
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Pure Live Seed

Seed is provided in Pure Live Seed (PLS) unless otherwise stated.

Pure Live Seed (PLS) expresses the viable seed content of a seed lot using its purity and germination or viability test results. It helps you compare seed lots and calculate how much bulk seed is needed to meet a specified PLS planting rate.

PLS weight and bag weight

PLS weight is not the same as the total weight of seed in a bag. For example, a lot with 80% purity and 75% viability contains 60% PLS: 80 × 75 ÷ 100 = 60. Supplying 10 lb PLS from that lot requires about 16.67 lb of bulk seed.

Use the current seed test and the stated basis of the mix specification. Germination calculations may include applicable hard or dormant seed. Seed-count estimates also require the number of seeds per pound; PLS alone does not provide a seed count.

What to check when buying a mix

Check whether each rate is stated in PLS pounds, bulk pounds, or a combination. A mix with both bases should not be described as having an all-PLS total.

PLS does not remove weed seeds or guarantee establishment. Review the seed label and analysis for weed content, and match site preparation, planting conditions and follow-up management to your project.

Sources: USDA NRCS, Understanding Pure Live Seed and The Importance of Seed Quality for Natural Resource Conservation.

Weight Conversions lbs. to oz.

0.01 pounds = 0.16 ounces

  • 0.1 pounds = 1.6 ounces
  • 0.25 pounds  = 4 ounces
  • 0.5 pounds = 8 ounces
  • 0.75 pounds = 12 ounces
  • 1.00 pounds = 16 ounces

White snakeroot flowers late enough to carry woodland plantings into fall. It grows in partial sun or light shade, where the soil is less likely to dry out under sustained direct sun.

For Ageratina altissima, choose partial sun to light shade and moist to slightly dry soil. Recorded habitats include moist to slightly dry deciduous woods; Woodland margins; Thickets; Shaded seeps; Bluffs; Riverside woodland meadows. Reported height: about 1½–3 ft.

Growth habit: spreads vegetatively through rhizomes and can reseed into new areas. Allow space for this growth between neighboring plants over several seasons, rather than spacing only for the size of a young plant.

Plant specifications

Key growing facts

Sunlight Partial sun to light shade
Soil moisture Moist to slightly dry
Height About 1½–3 ft
Bloom season Late summer through the fall
Show / hide ▾Growing & planting details
Growth habit Spreads vegetatively through rhizomes and can reseed into new areas
Root form Fibrous roots; Rhizomes
Soil pH Published cultivation guidance lists alkaline, neutral soil conditions; no optimal numeric interval is established.
Cultivation hardiness zones Zones 3a–9b (general cultivation guidance)
Deer browsing Deer resistance reported in cultivation guidance; browsing remains possible.
Plant toxicity Poison characteristics are reported; listed parts: flowers, leaves, roots, sap/juice, seeds, stems. Pet safety is not established.

Plant identification & seed reference

Botanical name Ageratina altissima
Other common names white snakeroot; Fall Poison; Richweed; Tremetol; White Sanicle; White Snakeroot
Plant family Asteraceae

Plant characteristics

Ageratina altissima (White Snakeroot) is a very common pioneering woodland plant reaching around 3-4 feet high with beautiful white flowers.  It can be aggressive in certain settings

  • Flower Color Purple/Pink
  • Flower Time June, July, August, September
Show / hide ▾Plant communities & associates

Illinois woodland and stream communities

Middle Fork Woods, Vermilion County (1999–2002 survey). Recorded in: dry-mesic upland forest — mature second growth; mesic ravine forest; dry-mesic savanna — old growth with canopy closure; southern flatwood forest and ephemeral pond; dry upland bluff — east-facing river slope; dry upland bluff — west-facing creek slope; dry-mesic upland forest — immature second growth; perennial stream corridor.

Dry-mesic upland forest — mature second growth — selected native associates: Carex pensylvanica, Carex rosea, Carex blanda.

Mesic ravine forest — selected native associates: Geranium maculatum, Phlox divaricata, Asarum canadense.

These plants share a recorded habitat; they were not necessarily found in the same small plot.

Show / hide ▾Native range & C-value

State nativity describes a broad range. Use the Chicago-region assessment for local context; a state listing does not establish county nativity.

Wetland indicator — NWPL 2022 Midwest FACU
C-value — Chicago region, Flora 2017 3
Chicago-region native — Flora 2017 Yes
Native range — U.S. states Alabama; Arkansas; Connecticut; Delaware; Florida; Georgia; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Nebraska; New Hampshire; New Jersey; New York; North Carolina; North Dakota; Ohio; Oklahoma; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Vermont; Virginia; West Virginia; Wisconsin
County nativity Not yet verified; occurrence records do not establish nativity.
Show / hide ▾Frequently asked questions

What are the ideal growing conditions for White Snakeroot?
Light: Partial sun to light shade. Soil moisture: Moist to slightly dry.

Is White Snakeroot deer and herbivore resistant?
Deer resistance reported in cultivation guidance; browsing remains possible. Even plants described as resistant may be browsed. Use physical protection where deer damage is a concern.

When should I expect White Snakeroot to bloom?
Typical flowering period: Late summer through the fall. Timing varies with location and weather.

Show / hide ▾Sources & ecological notes

Illinois woodland records: Larimore, Phillippe & Ebinger (2008), Middle Fork Woods flora, Appendix I. © 2008 University of Illinois Board of Trustees, CC BY 4.0. Habitat records transcribed, selected and linked to catalog names by Natural Communities. Survey: 1999–2002.

Native range & ecological ratings: Flora of the Chicago Region (2017), via Universal FQA; USACE Chicago FQA (2017); Kew WCVP / Plants of the World Online; USACE National Wetland Plant List.

Growing conditions & other references: Illinois Wildflowers, John Hilty; NC State Extension Plant Toolbox.

Native range does not identify the origin of the seed or plants offered. Community and wildlife records apply to the locations and conditions described.

Research notes & credits

USACE/ERDC fqadata — Chicago Region FQA 2017. Herman, B., Sliwinski, R. & Whitaker, S. (2017), Chicago Region FQA Calculator; distributed by USACE/ERDC in fqadata under CC0. Values may differ from Flora of the Chicago Region (2017). CC0 dedication. Retained for comparison; the displayed C-value follows Flora database 80.

Range data: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew; 4 June 2026 release, accessed 7 September 2026. © The Trustees of the Royal Botanic Gardens, Kew. CC BY 3.0; selected and reformatted. Kew cannot warrant the quality or accuracy of these data. This use has no Kew endorsement.

Flora rating attribution: Kenneth Johnson (2018), Flora of the Chicago Region UFQA Database, following Gerould Wilhelm and Laura Rericha (2017), Flora of the Chicago Region: A Floristic and Ecological Synthesis. Individual rating facts are presented with original commentary; the calculator’s software license is not treated as a license for the underlying Flora publication.

Growing guidance: Illinois Extension — Keeping deer out of the yard and garden. Selected facts in original wording. General deer advice is not a species resistance rating.

Planting references and review

Reviewed: 2026-09-26

Plant spacing:Species-specific spacing needs review. Select a spacing suited to your site and planting design.

Seeding rate: Use a site- and method-specific specification. No verified automatic species rate is supplied.

Seed preparation: A species-specific preparation method and named code system need confirmation for the supplied seed lot.

Seed Shipping & Care

Seed ships all year and typically ships within a week of an order being placed.

We have attempted to put together some basic information regarding native seed installation, establishment, and maintenance.  We hope you find it helpful.  If you need further assistance on native seed establishment, please schedule a free consolation call here.

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