“Every gardener dreams of the ideal plant—one that has interesting structure and beautiful flowers, thrives on neglect, draws gasps of admiration from the neighbors, and comes in enough varieties to fascinate you for a lifetime. What they are dreaming of is, in a word, a succulent.”—THE WORLD OF CACTUS & SUCCULENTS AND OTHER WATER-THRIFTY PLANTS, by Alice Quiros and Barbara Young
A succulent, strictly speaking, is any plant that stores water in juicy leaves, stems, or roots to withstand periodic drought. The reduced leaf surface of succulents cuts down on transpiration, which is water vapor lost through the minute pores in the leaf called stomata. There are other water-thrifty succulents, such as jatrophas and dioscoreas, which respond to a limited water supply with a brief growing season, extended leafless dormancy, and storage of extremely infrequent rainwater in their bulbous rootstock. Practically speaking, gardeners of succulents exclude such fleshy plants as epiphytic orchids and include in their garden collections many desert plants (yuccas, puyas) which are not fleshy.
Most succulents come from desert or semi-desert areas in warmer parts of the world. Mexico and South Africa are two very important sources. Some succulents come from colder climates where they grow on sunny, rocky slopes and ledges. Some succulents make good ground covers; others can be planted between stepping stones or used to create patterns in small gardens. Many succulents have showy flowers. Large-growing succulents are often used as important focal points in a landscape.
What is the difference between a cactus and a succulent? Cactus is the name of a large family of plants all of which are succulents. Small areas on the epidermis bearing clusters of spines or hairs, called areoles, are the distinguishing features that determine a succulent to be a cactus. All cacti are native to the Americas—from Canada to Argentina, from sea level into high mountains, in deserts or in dripping jungles. Many are native to drier parts of the Western United States. Certain succulents resembling cacti, called euphorbia, have spines (instead of areoles) in pairs on the angles of their ribs. THE WORLD OF CACTUS & SUCCULENTS AND OTHER WATER-THRIFTY PLANTS further muddles our understanding: “It is not true, though sometimes said, that spines are the distinguishing characteristic between cacti and succulents. There are cacti that are not prickly, and prickly succulents that are not cacti. Cacti have areoles (spine cushions) and other succulents, even if they are spiny, lack these spine cushions. Plants are classified into botanical families on the basis of their reproductive systems—not by external characteristics such as leaf form or flower color or habitat or even degree of prickliness.”
Members of the cactus family may have stems shaped into cylinders, pads or joints which store water in times of drought. Their thick skin reduces evaporation, and most species have spines to protect plants againt browsing animals. Flowers are usually large and brightly colored to attract pollinators; fruit may also be colorful and is sometimes edible to people as well as many desert animals. Cacti range in height from a few inches to 50 feet tall. Gardeners use larger species to create desert landscapes. Interesting forms and brightly colored flowers on smaller cacti are perfect for flower pot or rock garden culture. Smaller species are grown in pots or, if sufficiently hardy, in rock gardens. Many easy-care succulents make attractive house or greenhouse plants.
Growing conditions in their original climates determine sun exposure requirements among succulents. Bright light is generally required by succulents, with some preferring full sun exposure. However, many popular succulents are native to countries where temperatures are not as extreme and sun not as intense as here in the Sonoran Desert. Large specimens for landscaping must thrive in full sun and well-drained soil. For succulents that cannot withstand full sun, plant them in locations that take advantage of filtered sunlight provided by native trees or shrubs. Some of our Southwest native cacti naturally grow within the light shade of a shrub or desert tree. If a succulent plant receives too much sun, the surface tissue will yellow. You must provide shade, or move the plant to a more appropriate location or the tissue will turn brown, indicating permanent damage. This is why many gardeners keep their succulents in pots which can be moved around during the year for best temperature control and sunlight exposure.
Most succulents can be propagated easily from leaf cuttings. Gardeners often plant many succulent cuttings together, displaying them in the same pot with the idea that as the tiny cuttings grow at different rates they will be separated and replanted when they are no longer attactive together. Though you can combine a variety of succulents you must consider their compatibility carefully. Mature size, water and temperature requirements may vary greatly.
Use a fast-draining soil mix, such as two to three parts pumice with one part potting mix. Water newly planted cacti carefully: roots are subject to rot before they begin active growth. When new roots are active, water thoroughly, then let soil dry before watering again. Reduce watering in the fall to allow plants to become dormant. Feed and water these plants well during warm weather for good display; taper off on fertilizer to encourage winter dormancy.
—Peggy Reynolds Klitzke
THE WORLD OF CACTUS & SUCCULENTS AND OTHER WATER-THRIFTY PLANTS, by Alice Quiros and Barbara Young, copyright 1977, Ortho Books
SUNSET WESTERN GARDEN BOOK, edited by Kathleen Norris Brenzel, copyright 2007, Sunset Publishing Corporation
DESERT LANDSCAPING FOR BEGINNERS; TIPS AND TECHNIQUES FOR SUCCESS IN AN ARID CLIMATE, edited by Cathy Cromell, copyright 2001, Arizona Master Gardener Press