Annual Bluegrass, technically known as Poa Annua has become a tremendous problem in many of the lawns here in the South. It is most recognized by its super seed head formation that usually takes place in our area during May & June. This low growing slightly clumpy grass will mature at only 4-6 inches in height and will be absolutely covered with clusters of seed heads. These viable seeds will be spread in many ways. Wind, mowing & birds are responsible for moving seeds from one location to another. Poa Annua is often found growing in patches simply because of the way it was started. Birds such as Robins will often feed on mature seed heads and their droppings will start new patches to form in the lawn. If the patches are left to grow to maturity then mowing willl spread the seeds further and thus the patch becomes larger each year. The mature plants seed out in May and June and then proceed to die off with hot weather leaving behind thousands of seeds on the surface to germinate in the Fall.
Control for Poa Annua is very difficult for several reasons. There is post emergent control only available for warm season grasses such as Bermuda & Zoysia. These controls are still only available for the lawn care professional or golf course personnel and not the homeowners. There is a pre-emergent control available to stop the new germination of these seeds that needs to be applied in mid August, thus what sparked this article. There are two main control products listed for Poa Annua and they are Barricade & Dimension. Barricade will offer slightly superior control but is generally hard to find without fertilizer and applying fertilizer in our area in mid August can sometimes be dangerous. Dimension is readily available without fertilizer and can be applied quite safely during our hot August weather. It is very important that these products get applied prior to the 1st of September because with the first cooling rain of the Fall Poa Annua will be germinating. The downside of applying these pre-emergents in the Fall is that it stops you totally from over-seeding your lawn. Yes I mean totally in the Fall, not delayed, not AT ALL. This year especially due to the drought and severe damage to the lawns over-seeding may well be needed so the decision to prevent this notorious winter weed will be even tougher. Enjoy the garden! -Mark (Head Guru)