Rothrock's Knapweed

Plectocephalus rothrockii

Native to:
Mexico, United States

📍 View on iNaturalist →

Taxonomy

Division:
Magnoliophyta | - Flowering plants
Family:
Asteraceae
Genus:
Plectocephalus
Species:
Plectocephalus rothrockii
USDA Symbol:
CERO

Growth Characteristics

Life Cycle:
Annual
Growth Habit:
Forb/herb
Height:
100 cm
Light Requirements:
Full Sun
Drought Tolerance:
High
Bloom Months:
jul,aug,sep
Bloom Colors:
purple, pink

Wildlife Benefits

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

Garden & Ecology Notes

Wildlife Value:
bees, butterflies
Deer Resistant:
Yes

Soil Requirements

Soil Type:
well-drained, sandy or rocky soil
pH:
6.0 - 7.5 (slightly acidic to neutral)
Drainage:
excellent drainage required
Moisture:
dry to moderate
Notes:
native to arid and semi-arid regions

Propagation & Germination

Stratification:
Cold/moist stratification required — 30–60 days
Germination Time:
14–30 days
Notes:
Seeds benefit from cold stratification for 4-8 weeks to break dormancy.

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

Source: Claude AI