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How To Keep Winter Bluegrass Weeds At Bay
Bluegrass germinates throughout the winter and can reseed even after being mowed over, making it a nuisance. To prevent it from growing, use a pre-emergent herbicide.
This means applying the weed killer preemptively, timing the applications carefully and deliberately at certain points in the year before seed growth occurs.
Apply the pre-emergent herbicides between August and November. The treatments will last approximately three to five months, after which you can apply post-emergents.
When temperatures don't rise above 75 degrees F for at least four days in a row, apply the first of two fall applications. Wait eight to 10 weeks for the second one in late fall.
Additionally, you may have to hit the problem areas again in the spring, usually somewhere between late January and early May.
As with the fall application, time your treatment right, and apply it to your lawn before the warm weather returns and the new growth begins.