Finely textured and uniform in appearance, lightweight cocoa hulls—the shells of cocoa beans— release a chocolatey scent as they decompose. Their rich brown hue darkens with age, adding contrast to your plantings. In humid climates, a harmless mold may form on the hulls. To prevent it, layer the shells no more than 1- to 1 1/2-inches thick. Be sure to look for varieties without theobromine, which can be harmful to dogs and other animals.
Blommer Cocoa Shell Mulch, from National Cocoa Shell, $5.99 per bag (2 cu. ft.).