Succulents evolved to store water in thick roots, stems or leaves during heavy periods of rain, enabling them to survive long periods with limited or no water. They are classified as xeriphytic plants, meaning they resist drought. This makes them an ideal for growing indoors or outdoors in areas where water is scarce or expensive.
Succulent Growth Cycles
There are both annual and perennial succulents, although perennials are most often found in nurseries. Cactuses, almost all perennials, are also succulents.
Annual plants live for one growing season, usually from spring through early autumn. Perennials live for three or more years, typically not flowering until their second year of growth.
The term perennial is not to be confused with hardiness, which is how much winter cold a plant will survive outdoors. Hardiness is measured by U.S. Department of Agriculture plant hardiness zones based on average winter low temperatures. Perennial species that flower in their first year can be planted in the spring and grown as an annual in USDA zones that are too cold for their natural survival. These are sometimes called "tender" perennials.
The different shapes and colors of succulents in an outdoor garden provide interest in the winter and complement other plants in the spring-to-autumn growing season. Many species have thorns on the edges or tips of their leaves, but there are thornless varieties as well.
Most succulents evolved in arid or semiarid climates. They like gravelly or sandy soil. Succulents do not like standing water, and fast-draining soils are essential in areas with periodic heavy rainfall. Planting them on a mound helps drainage issues. They like sun and heat, so facing them on a slope facing south is ideal.
Master gardeners in San Mateo and San Francisco counties in California watered their succulent garden for only five minutes six times a year. In comparison, they watered their vegetable and flower gardens twice weekly for six months.
Sedums, ice plants, sempervivums, agaves and yuccas, including the following examples, are among the perennial succulents commercially available:
Low-growing perennial sedums (Sedum spp) are good for rock ground covers, and taller varieties are useful for borders. They have fleshy stems, thick succulent leaves and yield clusters of star-shaped flowers. They will grow in U.S. Department of Agriculture plant hardiness zones 3 through 9.
Ice plants also make attractive ground covers. Cooper's hardy ice plant (Delosperma "Cooperi," USDA zones 6 through 9) grows into a carpet of pinkish-purple flowers in summer through early autumn.
Perennial hens and chicks (Sempervivum spp., USDA zones 5 through 10) grow up to 8 inches high in rosettes of fat, thornless leaves, flowering from June through July.
New Mexico century plant (Agave parryi var. neomexicana, USDA zones 5 through 10), has gray-green leaves tipped with burgundy spines, growing 1 1/2 feet high spreading 2 feet wide.
Spanish bayonet (Yucca baccata, USDA zones 6 through 11), has swordlike, thick leaves and grows up to 3 feet tall. It yields white blossoms from early spring through late summer.
The attractive, hardy prickly pear cactus (Opuntia humifusa, USDA zones 5 to 10) is a low-growing spreading cactus that gives showy displays of bright yellow flowers in late spring and early summer.
Annual succulents are less often found than perennials.
The annual love-lies-bleeding (Amaranthus caudatus), typically planted indoors six to eight weeks before the last spring frost, grows from 2 to 4 feet tall, yielding long tassels of red, petal-less flowers that hang down 12 inches or more.
Green purslane (Portulaca Oleracea), an annual, grows rapidly up to 1 foot tall and 1 foot wide, yielding whitish flowers from late spring to early autumn. It likes full sun and moist soil.
Mezoo trailing red (Dorotheanthus bellidiformis "Mesbicla"), grows 3 to 6 inches high, forming mats of apricot, magenta, orange, pink, yellow and reddish purple blossoms from late spring through summer. It is a tender perennial grown as an annual in climates colder than USDA zones 9 and 10.