Hill's Thistle

Cirsium pumilum var. hillii

Native to:
Canada, United States

Taxonomy

Division:
Magnoliophyta | - Flowering plants
Family:
Asteraceae
Genus:
Cirsium
Species:
Cirsium pumilum var. hillii
USDA Symbol:
CIHI

Growth Characteristics

Life Cycle:
Perennial
Growth Habit:
Forb/herb
Height:
80 cm
Light Requirements:
Full Sun
Drought Tolerance:
Medium
Bloom Months:
jun,jul,aug
Bloom Colors:
pink, purple, magenta

Wildlife Benefits

Bees:
★☆☆☆☆ Documented bee visitation (GBIF)
Butterflies & Moths:
★☆☆☆☆ Documented Lepidoptera association (GBIF)

Keystone Species Ranking

Pollen Specialist Bee Keystone:
★★★★☆ Native pollen specialist bee species supported by this genus (NWF)

Garden & Ecology Notes

Wildlife Value:
bees, butterflies, birds
Deer Resistant:
Yes
Fire Ecology:
Fire adapted — tolerates or benefits from fire
Fire Notes:
Adapted to prairie fire regimes; resprouts from deep taproot following fire. Fire helps reduce competition.

Soil Requirements

Soil Type:
sandy, well-drained, nutrient-poor soil
pH:
5.5 - 7.0 (slightly acidic to neutral)
Drainage:
excellent drainage required
Moisture:
dry to moderate
Notes:
Prefers open, sunny habitats like prairies and savannas

Propagation & Germination

Stratification:
Cold/moist stratification required — 60–90 days
Germination Time:
14–30 days
Notes:
Seeds require light for germination. Cold stratification improves germination rates.

The above propagation data sourced from Claude AI

Pre-treatment: Cold-moist stratification for 30 days at 1–5°C (34–41°F).

Source: Claude AI