Maintaining Cacti and Succulent Plants

There's no mistaking the fact that the familiar prickly pear is indeed a cactus, because it's loaded with spines. On the other hand, the ever-popular jade and aloe vera are succulents, but not cacti.

Spines on various cacti are the most versatile and effective design features in the entire plant world (figure B). They serve many functions, the most obvious of which is physical protection. The spines also absorb and reflect sunlight so that the internal temperature of the plant remains fairly constant both day and night. They also function as drip tips--collecting moisture from mist, dew, fog and light rain and channeling it down to the root system.

Because cacti have adapted well to adverse conditions, they make great houseplants. Where other plants might fail in the hot, dry atmosphere of the typical living room--or barely survive--cacti often thrive. In fact, most people lose their plants from pampering too much; however, it would be a mistake to assume that cacti don't need any attention.

First of all, these plants require a lot of light, and a southern or southeastern exposure is ideal for most species. A sunporch is ideal for growing cacti--and so is a greenhouse--but if all you have is a sunny windowsill, that'll work fine. Don't put the plants too close to the glass, however, because the light in the summer can be too intense and drafts in the winter can create problems too.

Cacti need pots that are porous--unglazed terra-cotta is ideal--so the potting soil can dry quickly. Glazed pots are attractive, but they don't dry out as fast, and that can lead to root rot in cacti.

The soil mix you choose is also important. Contrary to popular belief, pure sand is far from ideal. Instead, a good mix contains somewhat equal parts of coarse sand and all-purpose potting mix. Many cactus gardeners have their own formulas, however, including various proportions of potting mix, coarse sand, perlite, peat moss and even leaf mold. The advantage of growing cacti in an improved mix is that the need for fertilizer is greatly reduced. Most cacti will grow fine with nothing more than a once-a-month feeding with a dilute liquid fertilizer or an occasional dusting with a half teaspoon of bone meal or limestone.

Like other houseplants, cacti hate being overwatered. The worst thing you can do is water them on a regular schedule. Instead, water them only when needed--when the soil is bone-dry. How long it will take for soil to dry out between waterings depends on the conditions of your home; you might need to water once a week or once every three or four weeks. Let the soil tell you when it needs water. During winter, some cactus growers even stop watering altogether from October until March. When you do water, make sure you soak the soil completely, but don't allow the water to stand in the pot saucer or you might end up with a root rot problem.

Many cacti are easy to propagate--especially from cuttings using a technique known as decapitation. James cut a stem from a mature prickly pear, let the cut tissue air-dry for about a week, then put the cutting directly in a potting mix. You can also graft one species of cacti to another, and the effect can be striking.