Pests in Gardens and Landscapes: Quick Tips

Weeds in Lawns

Published   5/16

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Smooth crabgrass.





Weeds occur in all lawns but seldom become problems in well-managed, healthy turfgrass. Poor maintenance practices — such as improper fertilization, watering, and mowing — can weaken turfgrass and predispose it to weed invasion. Total eradication of weeds isn’t realistic or necessary for most lawns. With good management practices, a lawn can be vigorous and attractive with little or no herbicide use.

Why is weed identification important?

  • Different weeds require different management approaches.
  • Many weed species are associated with particular lawn conditions, such as overwatering, compacted soil, or low fertility. Identifying the weed species can give an indication of the underlying lawn care problem, which can be corrected.
  • Visit for help identifying weeds.

Prevent weed invasions with proper lawn care.

  • Make sure to grow an appropriate turfgrass species for your area.
  • Regularly check sprinkler heads and adjust if needed.
  • Water deeply and infrequently.
  • Mow regularly, and remove no more than one-third of the leaf blade at each mowing.
  • Fertilize up to four times a year with no more than one pound of actual nitrogen per 1,000 square feet per application.
  • If needed, alleviate soil compaction with aeration.
  • Remove thatch if it is more than half an inch thick.

See the UC Guide to Healthy Lawns for complete information on lawn care.

When weeds invade:

  • Identify the weed species.
  • Determine if there is an underlying lawn care problem such as improper fertilizing, watering, and mowing, and correct it.
  • Remove weeds by hand when they are young and before they flower, set seed, form vegetative parts, or spread into patches.
  • Use herbicides as a last resort, and combine with proper cultural control.
  • If used, choose an herbicide labeled for the species of weed you are trying to control and one that is safe for use on your turf type.
  • Avoid fertilizer products containing herbicides.
  • Renovate or replace weak areas of lawn with vigorous new turf.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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