As we begin to approach summer more and more lawns will begin to show signs that they have Poa Annua or Annual Bluegrass.  Contrary to its name Annual Bluegrass can be found in both annual and perennial varieties.  Annual bluegrass is a weed that for a short time looks like Kentucky Bluegrass, except it is slightly lighter in color and has a courser texture.  In late spring, early summer, Annual bluegrass will develop short seed heads.  As the weather gets hotter the weed will start to die off, leaving empty patches in your lawn.
Annual Bluegrass is very common and most lawns will have some signs of it.  But it doesn’t take much for this little problem to become a big nuisance.  One of the biggest contributors to Annual Bluegrass is mowing the grass too short.  When you cut your lawn at a height of 2 inches or less you are actually damaging the lawn turf (typically Kentucky Bluegrass) and encouraging the growth of the Annual Bluegrass weed.  When Kentucky Bluegrass is cut higher at the recommended 3 to 3.5 inches in the summer months it will be healthier and develop deeper roots enabling it to discourage the Annual Bluegrass. 
As with consistent mowing practices, good irrigation practices are also important in controlling Annual Bluegrass.  When a lawn is over watered it will encourage weed growth.  One of the biggest mistakes we see in the lawn care business is irrigation systems that are timed to go on every day for 20 minutes or more.  Kentucky Bluegrass, which is the most common lawn grass we see in the Boise, Idaho area, prefers deep infrequent watering around 1 to 1.5 inches a week.  Early morning watering is best so that the lawn can have time to dry out and discourage disease and fungal growth as well as weeds.
If you have a problem with Annual Bluegrass in your lawn it is advised that you bag your clippings.  This will prevent the seeds (at least some of them) from going back into the soil.  You can also remove the weeds before they go to seed and overseed in those areas with the appropriate turfgrass.
It is also recommended that you have your lawn treated with a pre-emergent herbicide that will keep the seeds from germinating.  Preemergent should be applied in late summer or early fall to be effective as Annual Bluegrass germinates when the weather turns cool and will continue to germinate over the winter.
A dense healthy lawn will make it harder for Annual Bluegrass to germinate and take root.  At Organic Solutions! Inc., we use the safest and most effective products available to improve the health of your lawn rather than just treat the symptoms.

For a free estimate on lawn care that will control the growth and spread of weeds such as Annual Bluegrass, give us a call, 208-884-8986, or email,

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