Water grass is a colloquial term for many types of grass-like weeds. Individuals have varying ideas of what type of weed refers to water grass but it usually encompasses quackgrass and tall fescues. The best defense against water grass is to keep the lawn strong and healthy with proper care. Knowing the type of turf you have helps you give your lawn its ideal requirements.

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Water the lawn when it's cool to conserve water.

Step 1

Mow the grass so it is no less than 2 inches tall. Mow more frequently if necessary to accommodate a taller grass. Cutting your grass too short leaves it sparse and open, allowing weeds to grow.

Step 2

Water grass deeply and less frequently. This encourages a hardier grass with longer roots. Give the lawn at least 6 inches of water once a week. Watering depth and frequency varies depending on the climate, soil type and weather. Water in the morning or evening to prevent the water from evaporating before it is absorbed into the soil.

Step 3

Reduce the amount of traffic on the law to prevent compaction. Compacted soil is hard on grass and allows the tougher weeds to push through.

Step 4

Identify the variety of water grass by using online sources or talking to staff at your local nursery. Use a weed killer that is specially designed for the type of water grass you are fighting. Spray herbicides directly onto the leaf blades, but always read the manufacturer's instructions for proper application.