Luckily, dollarweed (Hydrocotyle umbellata) in lawns is susceptible to most broadleaf weed killers, which you can buy at nurseries and garden centers under many brand names. Read the label carefully, though not all weed killers work on all lawn types. If the dollarweed has crept out of your lawn and into planting beds, you won't be able to use a broadleaf weed killer, because it will also kill the nongrassy plants in the planting beds. Dollarweed thrives in wet conditions. Keep the infested area as dry as you can without harming the lawn or ornamental plants. Drying out the planting area alone often significantly reduces dollarweed growth.