How Can I Control Clovers?

Do you have clover invasion in landscape area?

Do you want to control clover with cultural control methods?

Do you need to prevent clover invasion in landscape areas?

Do you want to control turfgrass clovers with herbicides?

Do you have clover invasion in established turfgrass?

Annual clovers can be controlled by hand-pulling, hoeing, or cultivation. Mulching, depending on the size and depth of the mulch, can prevent seedling establishment. Before seeds germinate, a 4-inch thick organic mulch can prevent the establishment of clovers. Organic mulch can also be applied after the seedlings have germinated but must be applied in a thicker layer (4 to 6 inches) and must cover the plants completely to block out all light. Organic mulches need to be reapplied each year to maintain the 4-inch-thick layer because they decompose and the thickness of the mulch declines over time.

Preemergent herbicides available for landscape use are effective but generally unnecessary in the home landscape where annual clovers are easily controlled by cultural methods. For landscape professionals, herbicide formulations that contain isoxaben are effective for controlling annual clovers and can be used around many woody shrubs and trees. Most established annual flowers tolerate this herbicide.

Postemergent control of clover is difficult. If the seedlings are small, glyphosate can be used in open areas provided desirable plants are not sprayed. Once annual clover plants reach 3 to 4 inches in height, control with herbicides is more difficult. The top may be burned, but the plants often regrow. None of the herbicides used in turfgrass for clover control is safe to use in ornamental plantings because they can damage desirable plants.

Both established annual and perennial clovers can be controlled with post-emergent herbicides. The best herbicide to use depends upon the species of turfgrass. Warm-season turfgrasses such as bermudagrass, zoysiagrass, and kikuyugrass will tolerate products containing mecoprop and dicamba but not triclopyr. Cool-season turfgrasses will tolerate all of the herbicides that control clover. The herbicide 2,4-D is not effective for clover control; it will injure the plant but does not control it.

Clover in established turfgrass cannot be controlled by fertilization or mowing of the grass. Once clover is established, the annual clovers can be controlled by hand-pulling before seeds are formed. Hand-pulling will need to be repeated as new germination occurs and desirable turfgrass is planted in weeded areas.

The invasion of clover into turfgrass can be reduced by using levels of nitrogen fertilizer that will promote grass growth but not the growth of clover. This can be achieved by applying 1 pound of active nitrogen per 1,000 square feet of turfgrass during each month of active turfgrass growth. Also, high phosphorus in the soil promotes the invasion of clovers. However, nitrogen applications should be carefully calculated and applied to avoid runoff of excess fertilizer to municipal drainage systems.