Poa Annua - King of the grassy weeds!
In one form or another all plants, including grasses, sprout a flower and attempt to produce a seed. The process can vary dependent upon surrounding conditions and animal activity but for the most part plants are pretty darn good at producing seed, after all they’ve been doing it for millions of years! It just so happens there is a particular grassy plant that can produce copious amounts of seed… Annual bluegrass, otherwise known as Poa Annua or simply poa, is a pest in your lawn.
Poa annua actually germinates in the fall starting in late August through 
the winter (winter annual weed); the same time you seed Fescue in this area. Poa annua will generally end its life cycle in Late May and June.
It is a prolific seeder and seed is generally viable the following year. It typically grows in areas that have poor compact soil and where your desired turf is thin or nonexistent. However, being that it is a common grassy weed in our area; it can be found anywhere, even in the middle of your lawn.
