Nonchemical Alternatives for Weed Management

Weeds in the landscape can be tough to manage. But there are many options for weed management using an integrated approach that combines nonchemical and chemical methods.

Creeping woodsorrel, Oxalis corniculata
(Credit: JM DiTomaso)

Identification:

• Start by identifying the weeds you want to manage. UC IPM has a weed photo gallery that includes most weeds found in California landscapes. Knowing how a weed grows and spreads is an important step in successful control.
• Once you know what weed or weeds you're dealing with, consult the Pest Notes series on weeds to find specific management options.
• Management options depend on whether the site is already planted or if you're installing a new landscaping. Develop a weed management plan before planting.

Cultural Controls:

• When you're installing new lawns or plantings, you can use soil solarization to control weeds prior to planting. Instructions on how to solarize soil can be found in the Soil Solarization Pest Notes.
• Selecting the right plants for your site and planting them at the right time will enable the plants to establish quickly, eliminating the need for additional herbicides.
• Choosing drip or subsurface irrigation or microsprinklers instead of rotor and turf-type sprinkler heads will also help in reducing weeds, since the water is placed at or near desirable plants.

Mechanical and physical controls:

• Use mulch and geotextiles (landscape fabrics) in landscape plantings to reduce the growth of weeds.
• Mow and trim as needed to prevent weeds from forming flowers or seeds.
• Cultivation, such as hand-weeding, can be useful to remove small weeds before they set seed.
• Young weeds in open areas can be controlled with small flaming or infrared units.
• Steam weeder machines are available that use superheated hot water or steam to kill weeds.

Chemical controls:

• A variety of other herbicides, both preemergence and postemergence, are registered for use in residential and urban landscapes. No single herbicide will control all weeds. Always read the label before use. Be sure to use the correct personal protective equipment to reduce your exposure to the pesticide.

For more general information, see the Pest Notes on Weed Management in the Landscape or Weed Management in Lawns.

[Article originally published as “Ask the Expert!” in the Fall 2019 issue of the Green Bulletin.]