Weed management in established lawns
The best defense against weeds is a healthy, vigorously growing lawn. Select a proper turfgrass species, follow recommended lawn establishment and maintenance procedures, and identify weed species when problems arise and before selecting management practices. Total eradication of weeds is not a realistic or necessary goal for most lawns; however, with good management practices a lawn can be practically weed free without the extensive use of chemicals.
Selecting turfgrass species
Different grasses are better suited under different conditions. Read more about the different turfgrass species to help you decide which grass species is best foryour particular needs. Here you can read about which species are best adapted to most California conditions, not adapted to hot climates, or adapted to summer heat.
Use good maintenance practices
Poor irrigation practices can weaken turfgrass growth, allowing weeds to invade. To maintain a healthy lawn, uniform coverage is needed. Sprinkler heads that are broken, obstructed, or set too low or too high may not reach all areas of the lawn and can result in dry or dead spots in an otherwise healthy turfgrass.
Read more about the best ways to irrigate your established lawn.
Each turfgrass species has specific mowing height requirements. Mowing some grasses too short can weaken the turfgrass and increase weed invasions. Alternatively, if some grasses are not mowed short enough, the thatch layer can build up, reducing water penetration and weakening the turfgrass.
Read more about how to mow established lawns.
Read more about the mowing requirements for common turfgrass species.
To maintain a healthy lawn, follow fertilizing guidelines carefully. Begin a regular fertilization program approximately 6 weeks after planting. In general, lawns need to be fertilized about four times a year with no more than 1 pound of actual nitrogen per 1,000 square feet per application.
Read more about fertilizing your established lawn.
Read about Practical Lawn Fertilization for requirements for specific turfgrass species.
Regular thatch removal will help keep your turfgrass healthy and competitive with weeds. Generally, you should dethatch your lawn when the thatch layer is more than 1/2 inch thick. For some species, such as zoysiagrass, bermudagrass, or Kentucky bluegrass, this may mean dethatching every year. For other species, such as tall fescue, dethatching may only be needed every 5 years or not at all.
Read more about dethatching your established lawn.
Heavy traffic can compact soil over time. Soil compaction restricts the flow of oxygen, water, and nutrients into the roots, causing the turfgrass to grow slowly and making it more susceptible to weed invasions. Alleviate soil compaction with regular aeration when turf is actively growing. Lawns on heavy clay soils or lawns with heavy foot or equipment traffic may need to be aerated several times a year while lawns with little activity may only need to be aerated once a year or less.
Read about equipment to use to aerate your lawn.
Read more about when to aerate your lawn.
Controlling occasional weeds by hand-pulling may be all that is necessary if you practice regular maintenance procedures. Hand-weeding is particularly important for preventing infestations of creeping woodsorrel, nutsedge, dandelion, spurge, dallisgrass, and bermudagrass. Remove weeds while they are still young and before they set seed or produce rhizomes or tubers. Remove small patches before they get large. Making this a regular habit will greatly reduce the number of weeds in your lawn. Be sure to remove the entire weed, including the root. A dandelion fork, or fishtail weeder, is useful for removing weeds with a thick taproot.
If you don’t know what kind of weed you have, the Weed Identification Key will help.
If your lawn is properly maintained, herbicides will generally not be necessary. When they are needed, use them as part of an integrated management program that includes good cultural practices. No single herbicide will control all lawn weeds, and not all herbicides can be used on all lawn species.
You must identify your weed problem(s) and turfgrass species before choosing an herbicide. A few of the most serious lawn weeds, such as some perennial grasses, cannot be effectively controlled with herbicides without killing the turfgrass as well.
Read more about Herbicides.