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If you are growing succulent plants, it’s helpful to know that some grow best during the fall and spring, and are summer-dormant, while others grow during the hot summer months through September and October. These succulents are known as winter-dormant.

The importance of these schedules is that succulents should be fed and irrigated during their growing periods and left on their own during their dormant periods.

Let’s consider a specific, popular group of succulents.

Aeoniums are in the summer-dormant category. These plants are members of the Crassula family (Crassulaceae). Other summer-dormant members of this family include Cotyledon, Crassula, Dudleya, Graptopetalum, Kalanchoe, Pachyphytum, and Sedum.

Most Aeoniums are native to the Canary Islands in the Atlantic Ocean, which are near Morocco and the north-west coast of Africa. Because this environment is similar to that of the Mediterranean Basin, these plants grow quite well in the Monterey Bay area and other parts of California’s central coast.

The genus Aeonium is noteworthy for its creation of rosettes of various mature sizes, from four to twelve inches, depending on the species. The genus includes about thirty-five species, of which three are the most popular garden plants:

• Aeonium arboreum: cultivars include the species (bright green rosettes on a branching stem); ‘Atropurpureum’ (maroon leaves when grown in bright light); ‘Zwartkop’ (very dark, almost black leaves); and “Garnet” (a ‘Zwartkop’ hybrid with red leaves).

• Aeonium davidbramwelli ‘Sunburst’ (large rosettes, pale yellow, white and green stripes, with pink tips).

• Aeonium haworthii ‘Kiwi’ (four-inch flowers with pale yellow centers when young, maturing to red and green).

The common names of A. arboreum include Tree Houseleek, and African Cabbage Tree. They will grow into tree-like forms up to three feet high by three feet wide, with trunks and branches. This is the plant’s natural structure in maturity, but many gardeners regard it as leggy and unattractive.

The usual management of Aeoniums that develop such forms is to “behead” the rosettes and replant them. This can be done at any time of the year, although some advisors recommend the end of the summer dormant period.

Generally, cut off the rosette with about six inches of stem. Leave the cutting to dry for two or three days to allow the cutting to callus. This action, which is recommended for stem cuttings of all succulents, limits the potential for stem rot that could result from moisture,

Once the stem cutting has formed its callus, insert the stem a couple of inches into the well-draining soil mix. This could be a commercial cactus mix or potting soil mixed 50:50 with perlite, vermiculite or gravel. It will develop roots within a few weeks.

This simple process, which can be repeated multiple times during the life of the plant, propagates the Aeonium in a low-growing form that can be installed as a single cluster of plants or placed in several locations within the garden.

Mature Aeoniums will develop flower stems from the center of the rosettes. Small, star-like flowers grow in clusters. Aeoniums are monocarpic: once they flower, they produce offsets, and the stem dies. With this in mind, some gardeners enjoy the flower cluster while it lasts, and others unceremoniously remove stems that begin to develop flowers.

Aeoniums are quite easy to grow in the Monterey Bay area’s climate. They prefer morning sun and afternoon shade, well-drained soil, and regular irrigation and fertilization during their growing periods. They are not deeply rooted, so they can be grown either in containers or in the ground.

Consider the addition of Aeoniums to your garden. The different species listed in this column offer options to suit your preference. Creative landscaping could involve pairing your preferred species with plants that contrast or complement the Aeonium’s color or form.

Tom Karwin is president of the Monterey Bay Area Cactus & Succulent Society, past president of the Friends of the UC Santa Cruz Arboretum, and a Lifetime UC Master Gardener (Certified 1999–2009). Visit ongardening.com for information on this topic. Send comments or questions to gardening@karwin.com.

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