Kentucky Bluegrass
Poa pratensis
Poaceae · grass grasslike · native
Last updated
NOT recommended as a monostand in western WA. Use as a minor component (10-30%) of seed mixtures to provide rhizomatous self-repair. High water requirement, disease susceptibility in maritime climate, and poor shade tolerance limit its utility as a primary lawn species in this region. In seed mixes, it provides the sod-forming growth that bunch-type species cannot.
Plant Profile
Size & Form
Height
12-24 in
Spread
Spreads aggressively by rhizomes; excellent self-repair capability. This is its primary advantage over bunch-type grasses.
Growth Rate
Moderate
Site Requirements
Light
Full Sun
Soil Drainage
Well Drained
Soil pH
6.0-7.0
Water
High
Drought Tolerance
Medium
Hardiness
Zones 2a–7b (marginal in Zone 8b)
Ornamental Interest
Bloom Time
may to july
Origin
Europe (despite the common name; has been in North America
Watch for this season
Powdery MildewHigh
Active Conidial Spread
RustHigh
Uredinial Stage (Summer)
Diseases: Regionally Documented (2)
Diseases: Other Associations (4)
Pests: Other Associations (3)
Phenological Calendar
View full calendar (5 stages)
| Stage | Typical Window |
|---|---|
| Spring green-up BBCH 09 | Mar 1-Mar 30 |
| Active vegetative growth BBCH 21 | Apr 1-May 15 |
| Peak spring growth BBCH 39 | May 1-Jun 15 |
| Summer stress / semi-dormancy BBCH 45 | Jul 1-Aug 31 |
| Winter dormancy BBCH 97 | Nov 15-Mar 1 |
Cultivars (1)
'General modern cultivars'
Modern KBG cultivars offer improved disease resistance, especially to leaf spot and rust, compared to older cultivars. Thousands of cultivars exist. In western WA, select cultivars rated highly for rust resistance and leaf spot resistance by NTEP.
In western WA, use only as a minor component (10-30%) of seed mixtures, primarily for its rhizomatous self-repair capability
Data Maturity Structured Multiple sources. Expert review underway.