Can You Regrow a Cactus From Its Arm?

Drying the Arm

• The arm or pad will have to dry for two weeks before it will be suitable to plant, because a fresh pad or arm will quickly rot if it is simply stuck in a pot and expected to grow. If it seems odd to leave a piece of cactus lying around for two weeks with the expectation that it will be able to sprout roots afterwards, remember that you're dealing with a cactus, which is more than capable of surviving a couple weeks of drying. You'll know the cactus is ready when the cut end has dried over and formed a callous.

Potting Mix

• You'll need a well-draining cactus potting mix if you want to grow the cactus indoors. The arm can be grown outdoors, too. Just choose a place in the vicinity of other cacti where you know the soil is very well-draining. The University of Arizona recommends that the potting mix be 50 percent organic matter and 50 percent inorganic matter, the latter serving primarily to enhance drainage. Keep in mind that a cactus can grow in a 1- to 2-gallon container for up to a year before it has to be repotted.

Potting

• Insert the arm into the potting mix so it stands up. The planting depth of the arm will vary depending on how large or small it is, but aim for one-third to one-half of its length to be buried in the potting mix, as Texas A&M University recommends. Some people like to dip the cut end in rooting hormone before potting, but that's entirely optional. If you are concerned about fungus, dip the cut end in sulfur, which acts as a fungicide.

Care

• A cactus cutting requires no more water than an adult cactus. Different types of cactus require different amounts of water, but, in general, the baby cactus doesn't need more water than its parent. It should be placed in bright light. If grown outdoors, some dappled shade will provide the right amount of light for the growing cactus.