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Dollarweed (Hydrocotyle spp.), also known as pennywort, is a warm-season perennial weed. It gets the common name, dollarweed, from its silver- dollar-shaped leaves. The leaves of dollarweed are round, bright green, fleshy and look like miniature lily pads measuring 1-2” in diameter with a scalloped edge. It has a low-growing habit that spreads by seeds, rhizomes and tubers.

Dollarweed is often confused with dichondra. One way to distinguish the two is by looking at the placement of the leaf stem. Dollarweed has a stem located in the center of the leaf while dichondra’s stem is located at the edge (see image below).

Dollarweed leaf on left and dichondra leaf on right.
Bert McCarty, Clemson University

Before starting a weed control program homeowners should realize that complete eradication of dollarweed (or any weed) from the landscape is not practical. A more practical approach is to control (not eradicate) the weed by limiting the infestation to a tolerable level.

Cultural Control

Dollarweed is a water-loving plant that can float. The presence of dollarweed indicates that there is excessive moisture in the area. Research at the University of Florida demonstrated a reduction in dollarweed just by reducing irrigation frequency (http://grove.ufl.edu/~turf/weeds/dollarweed.html). Monitoring moisture levels and evaluating irrigation frequency are the first steps to controlling dollarweed. Landscape plants and lawns require one-inch of water a week for optimum growth.

A properly maintained landscape that is not stressed by insects, diseases, drought or nutrient imbalance is the best defense against weeds. Proper mowing height of lawns and a 3-inch thick mulch layer around trees and shrubs will prevent the invasion of weeds.

Chemical Control

Lawns: Dollarweed thrives in weak, thin turf with excessive moisture. The first defense against dollarweed is to reduce moisture levels and modify cultural methods (i.e., proper mowing height and irrigation).  After taking steps to modify the lawn care techniques, a chemical control may still be necessary to further reduce the dollarweed population. Herbicides should be chosen according to turf species and applied in late spring (after full spring green-up of the lawn) when weeds are small. Herbicide effectiveness is reduced as weeds mature.

Antrazine (Hi-Yield Atrazine Weed Killer, Image for St. Augustine & Centipedegrass, Southern Ag Atrazine St. Augustine Weed Killer, and Spectracide Weed Stop for Lawns Conc. for St. Augustine & Centipede Lawns) can be applied to St. Augustinegrass and Centipedegrass up to two times a year. For maximum effect atrazine should be applied once in the fall and again in late spring (after spring green-up). Atrazine has a pre- and post-emergent effect on weeds, which means it helps to control both emerged weeds and weed seed. It should NOT be applied to newly seeded lawns due to detrimental effect it has on seed germination. Delay atrazine applications to newly sodded and springged lawns until it is well-established and actively growing. CAUTION: Atrazine can travel through soil and enter ground water, please read the label for all environmental precautions.

Dollarweed in a lawn.
Bert McCarty, Clemson University

A three-way herbicide may be used safely on bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass and tall fescue. The active ingredients of a three-way herbicide include the following broadleaf weed killers: 2,4- D, dicamba, and MCPP (such as Ferti-lome Weed Out Lawn Weed Killer with Trimec®, Bayer Advanced Southern Weed Killer for Lawns, and Spectracide Weed Stop Weed Killer for Lawns). Herbicides containing 2,4-D should be applied at a reduced rate on St. Augustinegrass and centipedegrass to prevent damage to these lawns. If a second application is needed, apply the herbicide in spot treatments. Repeated applications of a three-way herbicide should be spaced according to label directions. CAUTION: Three-way herbicides should not be applied during spring transition (green-up of lawn) or when air temperatures exceed 90 ºF. A newly seeded lawn should be mowed a minimum of three times before applying a herbicide.

Imazaquin (Image Nutsedge Killer) can be applied safely to bermudagrass, St. Augustinegrass, centipedegrass and zoysiagrass. Apply imazaquin in the spring (after spring green-up) when weeds are small. A second application can be made in six weeks after the initial application. Do not apply to newly planted, plugged or sodded turfgrass.

Once dollarweed has been eliminated in areas of the turf, bare spots will be left behind. To prevent the invasion of new weeds in these bare spots fill them with plugs or sprigs of the desired turfgrass.

Landscape Beds: In landscape beds dollarweed can be hand dug or controlled with a herbicide. Dollarweed is a perennial weed that can emerge from seeds, tubers and rhizomes. Once dollarweed has made its way into the landscape bed a herbicide may be necessary if hand pulling is not practical.

Glyphosate (such as Roundup Original, Eraser Systemic Weed & Grass Killer, Quick Kill Grass & Weed Killer, Bonide Kleenup Grass & Weed Killer, Hi-Yield Super Concentrate Kill-zall Weed & Grass, and Green Light Com-Pleet 41% Systemic Grass & Weed Killer) can be used for spot treatments around ornamental plants. Glyphosate is a non-selective herbicide that should be used with caution. Do not allow glyphosate spray mist to contact ornamental foliage or severe injury will occur. A cardboard shield may be used to prevent glyphosate spray from drifting to nearby ornamentals.

Imazaquin (Image Nutsedge Killer) is a selective herbicide that can be applied safely to certain landscape plants; see product label for a listing of the plant materials. Imazaquin should not be applied around the root zones of plants not on the product label. It is best to apply imazaquin when weeds are small (early spring). A second application can be applied six weeks later if necessary.

Glyphosate and imazaquin are both more effective when weeds are actively growing and should not be applied under drought conditions. As with all pesticides, read and follow all label instructions and precautions.

Thanks to Sarasota landscaping for this information.

Thanks to the University of Clemson for this information.