Giant Mountain Aster Canadanthus modestus
Giant Mountain Aster is a perennial wildflower native to Alaska, Canada, and the lower 48 states. It grows to 3 ft and blooms Jul in part shade – shade, with brown fruit.
More about this plant
Canadanthus is a North American monotypic genus of flowering plants in the family Asteraceae. The only species is Canadanthus modestus, commonly known as great northern aster or western bog aster. It is native to most of Canada and to northern parts of the United States. Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Part shade – shade
- Soil & moisture
- Medium moisture
- Soil pH
- 5.7–7.5
- Fertility need
- Low
- Adapts to
- Medium (loam)
- Hardiness
- USDA zone 4+
- Height
- 3 ft
- Spread
- Moderate
- Growth rate
- Moderate
- Growth form
- Rhizomatous
- Lifespan
- Perennial · short-lived
- Foliage
- Broadleaf · medium texture
- Active growth
- Spring & summer
- Fruit
- Brown persists into winter
- Flower colour
- Blue AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed
- Seed starting
- No stratification needed
- Seeds ripen
- Summer – Autumn seed-collection / harvest window
- In the trade
- No known commercial source
- Deer browsing
- Low often deer-resistant
- Resprouts if cut
- No
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →✦ Bees 12 bee visitors
12 native & managed bee species are documented visiting Giant Mountain Aster :
Wildlife & visitors 3 nectaring
Open records of who else uses Giant Mountain Aster — a generalist food-web signal, kept separate from the keystone Ecological Value.
3 adult butterfly & moth species are recorded nectaring at its flowers:
Across 24 U.S. vegetation-survey plots that recorded Giant Mountain Aster, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.
Related plants
More Canadanthus →
How we know this (2) Methods & honest limits
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (33) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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