Species · forb

Compass plant

Silphium laciniatum

Compass plant (Silphium laciniatum) is one of the great long-lived prairie forbs, sending a taproot 12 to 15 feet deep and orienting its deeply cut basal leaves north-south. Its large yellow flower heads feed bees and its seed feeds goldfinches, and its presence signals a serious, high-quality prairie planting.

Category
forb
Mature height
5–9 ft
Bloom window
July–August, large yellow sunflower-like heads
Moisture
Mesic to dry-mesic
Seeding rate
0.1–0.5 PLS lb/ac in a mix
Seeds per lb
~9,000
Native range
Tallgrass prairie

Why landowners plant compass plant

  • Root systems reaching 15 feet provide drought resilience and deep carbon storage.
  • Conservative species that raises habitat-quality scoring on CRP and grant rankings.
  • Large seed is a favorite of goldfinches and other seed-eating songbirds.
  • Plants can live 50 to 100 years, anchoring the stand for the long term.

Site fit

Plant on deep mesic to dry-mesic prairie soils with full sun. Avoid shallow, rocky, or saturated ground where the taproot cannot develop.

Establishment

Large seed with a strong cold-moist stratification requirement — dormant seeding only. Plant 1/4 to 1/2 inch deep. Very slow: expect leaves for two or three years and first bloom in year four or five.

Management

Highly fire tolerant once established. Because seed is large and costly per pound, it is often specified at low rates or interseeded in patches.

CRP practice fit

CP25

Premium conservative forb in high-diversity rare and declining habitat mixes.

CP42

Included in high-end pollinator mixes for summer bloom and structure.

Featured mixes with compass plant

Pairs well with

Big bluestem · Indiangrass · Prairie blazing star · Gray-headed coneflower

Frequently asked questions

Why is compass plant seed so expensive per pound?

Compass plant has only about 9,000 seeds per pound compared with over a million for many small-seeded forbs, and plants take four to five years to produce seed. Both factors make it one of the costliest species per PLS pound in a mix.

How long does compass plant take to bloom?

Four to five years from seed. It invests early growth in a taproot that can reach 15 feet, then flowers reliably for decades — often outliving the CRP contract that established it.

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