Cacti are some of the most rewarding houseplants, as long as you have adequate light. Few flowers can compare in color, size or beauty, even though they appear only once a year. Most cacti grow slowly, so space is usually not a problem. They are generally very tough and adaptable. Contrary to popular belief, they do not “thrive on neglect”, but rather, like most plant species, they “thrive” on tender loving care…they will, however, “survive” on neglect.
Desert type cacti do best in a very sunny south- or west-facing window (minimum of 4 to 6 hours of direct sun.) Wooly and heavily spiny species require the most sun, while spineless species normally require mid-day shade. A reddish discoloration may indicate that your plant is at or beyond the intensity of sun it can tolerate. Epiphytic, or tree-dwelling, cacti (e.g., Christmas cactus) prefer less sun (and more humidity) than do desert types.
When you water, water thoroughly, and allow the soil to dry before watering again. An exception
would be the Christmas cactus which does not want to dry completely. Judging when to water a cactus can be tricky…it can be difficult to feel the soil, so you might try lifting the pot when freshly watered, and then checking periodically to see how the pot gets lighter as root ball begins to dry. Another way to check for moisture is to feel the sides of a clay pot…cool and damp when the root ball is wet. Some plants can be checked by feeling the “leaves” or stems, which will be plump and firm when the plant has enough moisture. Most cacti prefer to be drier in winter than in the warmer growing season. Never let your cacti stand in drainage water longer than about 30 minutes.
Fertilize cacti with a higher phosphorous fertilizer (5-10-5, or 10-30-20, etc.), as too much nitrogen (the first number in the fertilizer formula) encourages excessive rapid green, weak growth. We recommend diluting the fertilizer more than the label instructions advise, as most cacti have adapted to growing in nutrient-poor soils.
Slow-growing cacti usually require infrequent repotting, which is great since handling these spiny plants requires both care and bravery! Use a pair of wooden tongs or a rolled up piece of newspaper to grasp the plant and ease it out of its pot. Always repot at or above the previous soil level to discourage rot.
While there are many wonderful succulent plants (from the Latin succus, meaning “sap” or “juice”), a true cactus can be identified by the cottony pad (areole) at the base of its spines. In other spiny succulents, the spines grow directly out of the flesh. Be aware that once you have a few cactus species, it is hard to avoid the desire to make a collection…there is so much variety in shape, size, color, and habit!