Annual Bluegrass is another ugly and unsightly weed in Saint Augustine grass and all other lawn types as well. Its bright green leaves and clumping characteristics can quickly overtake a lawn transforming what would otherwise be a beautiful lawn into a complete mess of weeds.
Annual Bluegrass will begin germinating underground about a month or more before Winter, and will start emerging from the soil and in our lawns at the beginning of Winter. Annual Bluegrass will continue to germinate, grow stronger, start clumping, and spreading as the winter months continue.
By the time Spring rolls around, the Annual Bluegrass is in full growth, easily outgrowing the Saint Augustine lawn and sitting above it in stark contrast to the lawn around it. This is also the time that Annual Bluegrass will begin going into full seed, making the Annual Bluegrass weed even uglier.
This same seeding will be planting out thousands of new Annual Bluegrass seeds into our turf for emergence in the following years. So if we have Annual Bluegrass this year, it will be worse next year, worse the year after, and so the lawn weed continues each year getting worse.
So if we have Annual Bluegrass in our Saint Augustine lawns, it must be treated as soon as possible.
Killing Annual Bluegrass In Saint Augustine Lawns
Annual Bluegrass is actually a very easy weed to kill, but only if it’s done at the right time.
Annual Bluegrass weed killer is diluted with water in a watering can or spraying bottle as per manufacturers guidelines, and applied to the entire lawn and not just to the area which appears most affected.
Be sure to measure the lawn before treatment to ensure the herbicide correct dosage is applied to the lawn.
Once the Annual Bluegrass weed killer is applied to the turf, the lawn is then lightly watered, which takes the herbicide down to the roots of the Annual Bluegrass where it does its work.
We should then begin seeing the Annual Bluegrass die off within 2 weeks.
When To Kill Annual Bluegrass
Annual Bluegrass must be treated at the right time of the year, otherwise the herbicide will have no effect whatsoever in killing the weed.
We have explained that Annual Bluegrass begins germinating underground about a month before winter, and that Annual Bluegrass herbicide acts on the roots of the weed, also underground.
With this in mind, Annual Bluegrass is best and most easily killed in the month prior to winter arriving, pre-emergent and before we can even see the weed. Past this time and we can still kill Annual Bluegrass in the first one to two months of winter.
However, the later we go into winter and the more mature the Annual Bluegrass becomes, the more difficulty we will have in killing it. Treatments done as late as the last month of winter may not even have any effect at all, while Annual Bluegrass treatments at the end of winter simply will not work, the weed will be just too strong and will easily outcompete the herbicide, resulting in no effect whatsoever. Plus the seeding for the following years has already completed.
A Plan To Kill Annual Bluegrass
So the questions are… how can we kill Annual Bluegrass before we can even see it in our Saint Augustine lawn, and what should we do if we were too late in the season to apply the herbicide?
If we missed the window to kill Annual Bluegrass in early winter or just prior to winter, or even mid-winter, then do not attempt treatments, it will only waste our money.
Mark down in your diary for next year to kill the Annual Bluegrass one month before the next winter is due to set in.
Because if we had Annual Bluegrass in our Saint Augustine lawn this year, its a guarantee it will be worse next year, and so it must be planned for and treated properly.
Once the Annual Bluegrass begins to go into massive seeding towards the end of winter, the best thing we can do here is to mow the lawn with a rotary mower and catch the clippings. A rotary mower uses a sucking action to pull clippings off the turf and into the catcher, and will thus do the same for many, but not all Annual Bluegrass seeds. So we are actually making the problem a little less worse for next year.
Mow more regularly when necessary to ensure that no Annual Bluegrass is left to seed for too long between mowings, otherwise we'll be allowing more seeds to fall back into the lawn for more weeds next year. Once the catcher is full, be sure to empty into the trash and not into the garden bed, because we don't want to be moving our Annual Bluegrass problem from our Saint Augustine lawn and into our gardens.
Multiple Annual Bluegrass Treatments
We will notice that not all the Annual Bluegrass will die in the Saint Augustine lawn after a single treatment of Annual Bluegrass weed killer.
If this is the case then a second treatment can be undertaken after 3 to 4 weeks if we are still in the safe time period for killing Annual Bluegrass.
We will also notice that even if we had wonderful success in killing Annual Bluegrass this year, that it will still emerge next year, and the year after. This is because not all weed seeds will germinate in a single year, but will instead stagger their emergence over several years as this gives the weeds their greatest chance for ongoing survival.
So be aware of this fact, and give another simple Annual Bluegrass treatment in the following years if necessary, and we'll have our problem of Annual Bluegrass in our Saint Augustine lawn completely under control.