Cacti
by Dr. Robert Black, Consumer Horticultural Specialist

Cacti are a group of plants that are not only easy to grow but offer a variety of shapes, color and form. They can be grown in any sunny, well-drained area and require little maintenance. They make excellent house plants and many hardy varieties may be grown outside.

The Cactus family (Cactaceae) is one of the most striking, distinctive, diversified and specialized. It includes about two thousand species; all are perennial and succulent. Their usually conspicuous flowers are so different from those of all other plant families that the cacti are unique and alone, with-out obvious relationship to other plants.

The distinctiveness of the cactus family shows itself not only in the flower structure but also in one characteristic, that, although possessed by every cactus plant, is absent in all species of all other families. This is the spine cushion or areole. Whether or not spines are present, all cacti have areoles. This is one way of distinguishing them, for these areoles differ in structure on different kinds of cacti.

The question is often asked, "Is this plant a cactus or a succulent?" This question is nonsensical because cacti are succulents. The true cacti are members of the botanical family Cactaceae and are distinguished from the succulent members of other plant families such as Euphorbiaceae by the structure of the flowers and the presence of the areoles on cacti. It therefore makes equally poor sense to call all succulents "cacti". The question should be: "Is this plant a cactus or some other succulent?"

Cacti require a sunny location with good drainage. They should be potted only in pots that have drainage holes. Replacing the top inch of soil with gravel is not only decorative but may also keep the plant from rotting at the base. A potting media of equal volumes of coarse sand, peat, and perlite is suitable for most cacti. Vertical plants should be planted in a container which has a diameter 1/2 the height of the plant and round cacti in containers with a diameter 2 inches greater than that of the plant. Care should be taken to prevent rot from developing on recently potted or repotted plants. Be sure the pot is dry before transplanting and transplant into dry soil. Wait a week before watering to allow for the damaged roots to repair.

Cacti do need to be watered and fertilized but not so frequently as other plants. Water the pots when they dry out. Unglazed clay pots require more frequent watering than glazed clay or plastic pots, small pots require more frequent watering than large pots.

Many cacti, but not all, require a rest period during the year for maximum growth and flowering. During the winter they prefer cooler temperatures, about 50 degrees F. and watering should be reduced and fertilization stopped. The natural rest period for cacti varies so after a month look for signs of growth. If by 3 months you see no signs of growth resume normal care.

Cacti can be grown from seed and many seed companies offer packets of mixed varieties. These can be fun to grow if you can stand the suspense. Some cacti seed take a year to germinate and it may take a few years to see what your young cacti will look like. Cacti may also be propagated from branches or offshoots. The offshoot should be removed from the plant and allowed to dry for 2 weeks. After the broken or cut edge has healed or suberized, plant it shallowly in dry media. Do not water for a week then water sparingly.