Preen Extended Control Weed Preventer is the longest lasting Preen yet, stopping weeds for up to six months per application. It is labeled for use around 600 plants in perennial flower beds; around groundcovers; trees and shrubs; and in xeriscape settings and rock gardens. Preen Extended Control is easy to apply. Simply flip open the top, tilt the bottle and start shaking it to evenly distribute the product granules on top of soil or mulch. Preen Extended Control Weed Preventer tackles many of the toughest weeds a gardener faces, including: dandelions, crabgrass, field bindweed, white clover, chickweed, henbit, purslane, California geranium, stinging nettle, horseweed or marestail, oxalis, spurge, lambsquarters and more.