Captain Jack's Deadweed Brew by Bonide is a patented, fast-acting non-selective weed, grass, algae, and moss killer designed for organic gardening. This Costco value set includes a 1-gallon ready-to-use (RTU) spray bottle and a concentrate refill, giving you both immediate use and economical long-term control in one package.

The formula utilizes concentrated fatty acids — specifically caprylic acid (C8) and capric acid (C10) — rather than glyphosate or other toxic chemicals. It works by penetrating the waxy cuticle of target plants, causing rapid dehydration and cell death. Visible damage typically appears within 1 to 2 hours of application, with full results in 1 to 2 days.

Captain Jack's Deadweed Brew can be applied to weeds in vegetable and flower gardens, landscaped areas, driveways, sidewalks, patios, fence lines, bark mulch, and around buildings. It also controls moss and algae on roofs, decks, and other hardscapes. The active ingredients do not translocate underground and will not harm the bark of mature, woody plants, making it safe to apply around the base of trees and shrubs. The product works in cool weather down to 55°F, does not stain brick, concrete, or asphalt, and leaves no harmful residue in the soil. People and pets may re-enter treated areas once the spray has dried. The product is EPA-registered and approved for organic gardening.