How to Kill Blue Grass

There are three basic varieties of bluegrass, including Kentucky bluegrass, annual bluegrass and rough bluegrass. Of these three varieties, annual and rough bluegrass are considered weeds because they are lighter in color than other grasses and they grow rapidly. Some bluegrass plants are perennials and return yearly, while others are annuals and last only one season. If you desire complete eradication, killing the grass is the best option.

Things You'll Need

• Pre-emergent herbicide
• Garden sprayer
• Post-emergent herbicide

Instructions

1. Apply a pre-emergent herbicide made for bluegrass to the entire surface of the lawn in early August. Fill a garden sprayer with the pre-emergent liquid and point the tip of the sprayer at the bluegrass. Spray the herbicide onto the soil, not the grass blades, until it completely saturates the surface of the soil to keep any existing bluegrass seeds in the soil from sprouting.

2. Apply a post-emergent herbicide in early September. Fill a garden sprayer with the herbicide and point the tip of the sprayer at the bluegrass. Spray the herbicide onto the grass until it completely saturates the blades of the grass.

3. Wait four weeks and apply a second application of post-emergent herbicide to the bluegrass to kill of any grass that survived the first application.

Tips & Warnings

• Do not apply the herbicide spray when rain is expected for at least two days, as it will wash away the chemicals.

• If you choose an herbicide formulated for bluegrass, it should not harm the remaining grass in the lawn.

References

• Purdue University Cooperative Extension Service: ID and Control of Annual Bluegrass and Rough Bluegrass in Lawns
• Pioneer Thinking: Understanding Weeds - How to Kill Them?