Annual Bluegrass , Poa annua L.
Revised Feb. 2008
In nature, annual bluegrass, Poa annua L. behaves as a true annual. It germinates in fall or spring when moisture is adequate and develops quickly, often flowering six to eight weeks after germination. In the Pacific Northwest we see it most commonly as a winter annual (Fig 1). After flowering and setting seed these annual types die typically from drought and leave dormant viable seed behind to germinate when moisture again becomes available. This efficiency in seed production makes annual bluegrass a major component of the seed bank of cultivated soils.