Unless the diameter of the column is less than 6 inches, you won't be able to just take a cutting and make a new plant from the top.

The best time of year to make a cutting is in spring. If the plant is tall and thin, cut it back to a 9 - 12-inch height and let the cutting "cure" (dry) for several weeks in a light but not directly sunny spot. After this time, dust the base entirely with a rooting hormone and plant into a pot of cactus potting soil. Do not water for at least a month. After the month, water the cutting just once and see if you can pull on it. If there is resistance, then roots are developing and you've got a new cactus started.

If the column is greater than 6 inches, you might consider donating the plant to a place where it can have more room to continue its life.

For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service