Crassula is a genus of about 200 accepted species of succulent plants in the family Crassulaceae. They are native to many different parts of the world. However, the species that are grown by succulent lovers, more than 150, are coming almost exclusively from the Eastern Cape of South Africa. Crassula ovata, commonly known as Jade Plant, is the most well-known species and probably one of the most popular succulents. In addition to the species, there are numerous attractive cultivars and hybrid.
The members of the genus are annuals or perennials, herbaceous or woody, and some have underground tubers. They vary in size and growth habit. These succulents range from groundcovers to shrubs or small trees. Some of them are trailing plants, some have rosettes with symmetrical leaves, and some of the annuals are aquatic plants. They have fleshy leaves with interesting shapes and coloring, and usually lovely, star-shaped flowers.
Crassulas are generally polycarpic plants. Some species are monocarpic and die after they flower.
Crassula was first formally described by the famous Swedish botanist Carl Linnaeus in 1753 as a genus with ten species. The genus name is derived from the Latin "crassus," meaning "thick," which refers to the fleshy plump leaves.
Growing Conditions for Crassula
Crassulas are among the most popular succulents to grow in gardens or containers both indoors and outdoors.
Crassula plants prefer full sun to partial shade. However, intense afternoon sun in the hottest period of summer can burn the leaves of the plants. A place with morning sun and afternoon shade would be perfect. Many Crassulas will stress beautifully to shades of red, purple, pink, orange, or yellow in response to more sunlight. In low light, even the reddest plants will revert to green.
Most Crassulas can be grown indoors if given enough light. Place your plants in a southern window where they receive at least 6 hours of direct sunlight.
Crassulas are not particular about soil pH, but they require very porous soil with excellent drainage. Most of them will do well in sandy or even rocky soil. Use commercial potting soil mixes designated for use with succulents or mix your own. In habitat, Crassula plants usually grow in rocky quartz fields.
These succulents prefer average summer temperatures between 65 and 70 ºF (18 and 21 ºC). In winter, cold to 50 ºF (10 ºC). Most Crassulas will tolerate some small degree of frost, but extremes of cold or heat will cause them to lose leaves and die. The biggest challenge with outdoor plants in winter is protecting them from temperatures below 32 ºF (0 ºC). Most species are grown outdoors in USDA hardiness zones 9a to 10b, 20 to 40 °F (-6.7 to 4.4 °C). However, elsewhere you could bring your potted plants indoors for the winter.
General Care for Crassula
Crassulas are easy to care for as houseplants or in the garden. They are perfect plants for beginners.
These plants have typical watering needs for succulents. Avoid overwatering by using the "soak and dry" method, where the soil is soaked with water, slowly drained and left to dry out before watering again. Reduce watering in winter, as your Crassulas can lose its roots if the soil stays cold and wet for extended periods. Too little water may cause the lower leaves to fall off. In habitat, the leaves shrivel as plants draw on stored moisture, then plump when rains return.
Potted plants require more frequent watering than those in the ground.
Crassulas are slow-growing succulents and do not need much feeding. They will benefit from a small amount of organic fertilizer in mid-spring when they start actively growing.
Many Crassulas do well in the same container and soil for many years. Repot as needed, preferably in spring, at the beginning of a period of active growth. Make sure the soil is dry before you begin repotting, then gently remove the pot. Knock away the old soil from the roots and place the plant in new or the same pot with a fresh potting soil mix. Leave you Crassula dry for a week or so, then begin to water lightly to prevent root rot in your plant.
Crassulas can benefit from occasional pruning to keep them healthy and compact. When plants start to get straggly or leggy, do not be afraid to cut them back. The pruning is best done in spring or after the blooming.
How to Propagate Crassula
Crassulas are generally started by leaves or stem cuttings. They can also be grown from seeds and offsets.
The easiest way is to propagate Crassulas from a single leaf. Always take at least two leaves because not every leaf you try to propagate will grow a new plant. Choose a healthy leaf and gently remove it from the plant by twisting it from the stem. Allow the leaves to callous for several days up to a week. Remove any leaf that starts to wither and die. Place them on well-draining soil mix and keep the soil slightly moist.
The fastest way to get a decent-sized Crassulas is to grow them from stem cuttings. This propagation method works best with plants that have branches. This process is most successful if done at the beginning of its active growth period. Select a healthy stem and remove it from the main plant. Allow the cutting to callous for several days before placing it in a well-draining soil mix. Water sparingly so that the soil is only damp until the cutting takes root. After it has rooted, you can treat it as you would a mature plant.
Propagating Crassulas with offsets is very easy because the parent plant has already done the majority of the work for you. To divide the offsets, brush away the topsoil until roots are visible, and gently pull them apart. Let the offsets dry out for several days and place them in a well-draining soil mix.
Propagating Crassulas with seeds is the slowest way to grow new plants. Sow the seeds in the spring or summer. They germinate best at temperatures below 70° (21 °C). Do not cover these seeds and other tiny seeds with a top layer. Avoid direct sunlight exposure. The seeds usually start to germinate after 1 to 3 weeks. Seedlings can be transplanted to individual pots when they have at least three leaves.
Pests and Diseases of Crassula
Crassulas are also susceptible to bacterial soft rot, powdery mildew, and black ring disease. These diseases are easy to identify and can be treated or dealt with when they are discovered.
Toxicity of Crassula
Crassula plants are generally nontoxic to people. Crassula ovata is slightly toxic to cats, dogs, and some other animals.
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