Big Bluestem

Andropogon gerardii

Poaceae · grass sedge · introduced

Last updated March 9, 2026

Data Coverage 3 of 6 dimensions

Site Data

Threats

Cultivars

Phenology

GDD Thresholds

Puget Sound

Quick Facts

Height

7 ft

Spread

6 ft

Growth Rate

Moderate

Light

Full Sun

Soil

Wet Tolerant

Water

Moderate

Hardiness

Zone Zones 6b–9b

Bloom Time

Jun 15-Aug 15

Stage	Typical Window	What to Look For
Bud break BBCH 07	May 15-Jun 15	Buds swelling and beginning to open; first green tissue visible
Leaf emergence BBCH 11	Jun 1-Jul 1	First leaves fully unfurled on new growth
Bloom start BBCH 61	Jun 15-Aug 15	First open flowers visible; flowers yellow
Bloom end / petal fall BBCH 69	Jul 15-Aug 31	Last petals falling; flower structures fading
Fruit/seed development BBCH 71	Jun 1-Aug 31	Fruit or seed structures forming; fruit color: brown
Fruit/seed maturity BBCH 85	Sep 1-Nov 30	Fruit fully colored and ripened; seed dispersal may begin
Leaf drop BBCH 93	Oct 15-Nov 30	Leaves yellowing and dropping; no significant fall color display
Dormancy BBCH 97	Nov 15-Feb 28	Leafless; no active growth; dormant buds set

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