Kentucky Bluegrass
Poa pratensis
Poaceae · grass grasslike · introduced
Last updated
Data Coverage 5 of 6 dimensions
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.
Quick Facts
Height
12-24 in (unmowed); mow to 1.25-1.5 in (western WA, as part of mix)
Spread
Spreads aggressively by rhizomes; excellent self-repair capability. This is its primary advantage over bunch-type grasses.
Growth Rate
Moderate
Light
Full Sun
Soil
Well Drained
Water
High
Hardiness
Zone Zones 2a–7b (marginal in Zone 8b)
Origin
Europe (despite the common name; has been in North America
Phenological Calendar
| 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 |
Diseases (6)
Pests (3)
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