How to Propagate Cactus. Propagation is an easy and inexpensive way to increase your collection of cactus and other succulents. There are a number of methods that can be used, but the key is knowing the best method for the varieties that you wish to propagate.
Grow cactus from seed. Seeds can be obtained from the ripe seed pod of any cactus that has flowered. Remove them from the pod and dry them at room temperature before planting. Sow seed in moist potting mix, moisten the seeds, and then cover with a fine layer of sterilized, coarse sand. Cover the pot with a plastic bag to retain moisture, and store at a minimum temperature of 70 degrees F. Expose the seeds to a small amount of sunlight each day.
Transplant seedlings. Once the young plants have developed, they can be transplanted to individual pots. Carefully lift a cluster from the pot and pull the seedlings apart, keeping as much soil around the roots as possible. Place each cactus into a pot that contains 3 parts cactus soil mix and 1 part gritty sand. Cover the surface of the soil with a 1/4-inch layer of gravel. Wait for about 3 days before watering the seedlings.
Take leaf cuttings. Remove healthy leaves from the plant, and let them sit for 1 to 2 days. Fill a pot with equal parts peat and sand. Insert each leaf into the soil mix, cover the surface of the soil with gravel. Repot each new plant about 2 weeks after the first new growth appears.
Use the stem. Many succulents can be propagated from the stem or sections of the stem. Cacti that grow in columns can often be propagated in this way. Remove a stem from the plant, cutting it into sections. Insert it just barely into a cactus planting mix and cover the surface of the soil with gravel. It can be repotted after it has been established.
Take pad sections. Some varieties of cactus produce "pads" that grow off the main stem. These may be cut off and rooted in the same manner as leaf cuttings. Offsets, which grow at the base of the main stem, may also be removed and potted in the same way.
Divide rootstock. Some plants such as aloe and some cacti that grow in clumps may be divided and replanted. Take the entire plant out of the pot and divide into several sections with a healthy shoot and root section in each clump. Using a regular soil mix, replant into individual pots. Water lightly and expose to limited sunlight until the plants are established.