Can You Use Mulch on a Cactus?

Benefits of Mulch

• Whether your cactus is in a well-drained pot or in an outside bed, it can benefit from inorganic or organic mulch. Mulch prevents the sunlight needed for weeds to grow. It holds in moisture and reduces the need to water as frequently. The proper mulch helps keep the soil temperature uniform. Some mulch also controls insects that can do damage to the cactus. Use 2 to 3 inches of inorganic mulch, or 1 to 2 inches of organic mulch, for a cactus.

Lava Rock

• Lava rock is inorganic mulch formed when molten lava is cooled by the air. It contains air pockets that retain water, but it also provides good drainage. Due to the deep underground formation of lava rock, it has trace minerals and micronutrients that leach out in small quantities and feed the cactus. It is available in red, black and charcoal gray. Choose a color that complements your house or other landscape design.

Stone Mulch

• Stone mulch is inorganic and replicates the desert environment of the cactus. Stone mulch is heavier than lava rock or wood chips, so it stays in place. It is also dense enough to protect a cactus from freezing. Stone mulch can be placed next to the cactus stem and will not cause root or crown rot. Different color choices can blend with or enhance the existing landscape. Stone mulches eventually work down into the soil and need to be replaced.

Organic Mulch

• In extremely hot climates, 2 or 3 inches of organic mulch around the cactus keep soil temperatures cool. Wood chips, leaves and pecan shells are good choices. Be careful when watering organic mulch. Watering a cactus too much can cause disease or rot. Avoid packing the mulch around the plant. A cactus does not do well when wet, organic material is placed next to its stem. Organic mulch decomposes and periodically needs to be replaced. It also tends to attract more insects than inorganic mulch

Mulch to Avoid

• Rubber mulch is not a good choice for cacti. It is highly flammable, and if a fire does occur, it is hard to extinguish. Rubber mulch also contains organic contaminants that are harmful to people and the environment. It leaches high levels of zinc into the soil which can kill the plant. When heated by the sun, rubber mulch has an odor that is offensive to some people.