Turf-type Perennial Ryegrass

Lolium perenne

Poaceae · grass grasslike · introduced

Last updated March 9, 2026

Data Coverage 5 of 6 dimensions

Site Data

Threats

Cultivars

Phenology

GDD Thresholds

Puget Sound

Primary lawn grass species for western WA. Well-adapted to maritime climate. Use as monostand (5–7 lb/1000 sqft) or up to 50% of seed mixtures. Quick germination (5–10 days) makes it excellent for overseeding and repair. Endophyte-enhanced cultivars strongly recommended. Most common lawn grass in Puget Sound residential landscapes.

Quick Facts

Height

8–24 in (unmowed); mow to 1.25–1.5 in (western WA)

Spread

Bunch-type; does not spread by rhizomes or stolons. Must be overseeded to fill bare areas.

Growth Rate

Fast

Light

Full Sun

Soil

Well Drained

Water

Moderate

Hardiness

Zone Zones 3a–9a

Origin

Europe, temperate Asia, North Africa

Phenological Calendar

Stage	Typical Window	What to Look For
Spring green-up BBCH 09	Feb 15–Mar 15	First green shoots visible as soil temps reach 40–45°F
Active vegetative growth begins BBCH 21	Mar 15–Apr 15	Rapid tiller production; lawn requires first mowing
Peak spring growth BBCH 39	Apr 15–Jun 15	Maximum growth rate; may need mowing every 4–5 days
Inflorescence emergence BBCH 51	May 15–Jun 15	Seedheads begin pushing up above mowing height if unmowed
Summer stress / reduced growth BBCH 45	Jul 15–Aug 31	Growth slows markedly when soil temps exceed 75–80°F; may go semi-dormant without irrigation
Growth cessation BBCH 93	Nov 15–Dec 15	Growth essentially stops; lawn remains green but dormant through mild western WA winters
Winter dormancy / semi-dormancy BBCH 97	Dec 15–Feb 15	Minimal growth; remains green in western WA unless prolonged freeze

Diseases (4)

Laetisaria fuciformis Red Thread Pyricularia grisea Gray Leaf Spot Rhizoctonia solani Brown Patch Pythium spp. Pythium Blight

Pests (3)

Tipula paludosa European Crane Fly Crambus spp. Sod Webworm Noctuidae Cutworms and Armyworms

Cultivars (1)

''Turf-type' (general category)'

Modern turf-type perennial ryegrasses have finer leaf texture, denser growth, lower growth habit, and better mowing quality than older pasture-type varieties. Many contain endophyte fungi (Epichloë/Neotyphodium) that provide resistance to surface-feeding insects.