Weed control: How to protect your lawn from invasive plants

Q: Due to the drought and water use restrictions, I reduced the number of times I was watering my lawn this summer. I now have weeds invading. Can you recommend a way to rid my lawn of the weeds without killing my grass?

A: Kudos to you for doing your part in conserving water during the drought.

When you cut back water to the lawn it slowed the growth of your grass and perhaps created some bare soil, if you had patches of grass that browned. This allowed for light to reach the soil surface and gave weed seed the opportunity to sprout.

The lawn care principles provided by the University of California Guide to Healthy Lawns all relate to the idea that the healthier the lawn, the less weeds will invade. Improper fertilizing, watering and mowing can weaken a lawn and make it a target for weed invasion. Go to http://ipm.ucanr.edu.

Advice on how you go about eliminating the weeds from the lawn will depend on the type of weeds that you have growing in the lawn. Start by identifying the species of weed and then determine if there is an underlying problem, beyond the reduction of irrigation that contributed to the weed problem.

Certain types of weeds are more likely to become a problem in the lawn if the soil is compacted or the lawn has not been fertilized or is over or under watered. The University of California Healthy Lawns website has a great chart that can help you identify some of these issues for the most common lawn weeds at http://ipm.ucanr.edu/TOOLS/TURF/PESTS/specialprob.html

To limit weed spread and prevent any more weeds from moving into the lawn, mow regularly and remove no more than a third of the grass blades at each mowing. When you mow, leaving the grass at a slightly higher height can also discourage weeds.

Fertilizing will encourage increased grass growth to out compete any weeds in the lawn. Depending on the type of grass you have in the lawn, fertilize about four times with one pound of nitrogen per 1,000 square feet of lawn. Now is a good time to fertilize cool-season lawns, such as fescue or mixed fescue and blue grass lawns.

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Master gardeners recommend using herbicides as a last resort, and only if the above management practices have not helped, and removing by hand would not be practical.

  • Avoid fertilizer products containing herbicides like “Weed and Feed” unless you have widespread broad leaf weeds throughout the lawn.

  • Use caution when using these products if you have any trees, shrubs or perennials planted in or around the lawn. Herbicides in these products can damage or even kill them.

  • If you do use herbicides, I recommend selecting one labeled for the specific weed found in your lawn and make sure it is safe for use on the type of turf you have. If most of the weeds are annual, then a pre-emergent herbicide applied in the spring may also help.

For more information, see “Pest Notes: Weed Management in Lawns” at https://bit.ly/3kKwMp7.

The Shasta Master Gardeners Program closed its booth at the Redding Farmers Market for the season. Reach master gardeners by phone at 242-2219 or email mastergardener@shastacollege.edu. The gardener office is staffed by volunteers trained by the University of California to answer gardeners' questions using information based on scientific research.

This article originally appeared on Redding Record Searchlight: Weed control: How to protect your lawn from invasive plants