Marin Master Gardeners
University of California
Marin Master Gardeners

Marin IJ Articles


Not So Crass -- Getting to Know the Crassula Family

February 25, 2008
Janice Austin
 

During the winter deluge, it may be hard to remember summer drought is on its way and with it, a need for hardy drought-tolerant plants. Meet the Crassulaceae family, succulents that are one of the most practical, low water use options, with highly varied, even stunning, choices for garden and container plantings.
There are more than 190 species in the Crassula genus, crassus meaning “thick,” referring to the plump, water-storing leaves of this succulent. The essential secret to success in cultivating Crassula is to provide them good soil drainage, through amending heavy clay soils with organic material or builder’s sand, or by planting them in rocky areas that slope, or in raised beds or even vertically, or tucked into unmortared retaining walls. Without this key factor, they will quickly rot.
While spiny cacti are succulents, they are not the only form of water-storing succulent, and members of Crassula are friendlier forms of succulents. Unlike invasive succulents like Ice Plant (Carpobrotus)and Red Apple (Aptenia cordifolio)which engulf Bay area coastal hillsides, Crassula make better, “user-friendly” choices for your garden. They can be far more interesting than the familiar solo sentry Silver Jade Plant (Crassula arborescens)at the front door.
Brilliant Crassula hybrids, like ‘Flame’ (Crassula coccinea) light up gardens with the seasons, leaves changing from spring greens to autumn reds. Or consider Ever Living Plants (Sempervivums), once planted on rooftops to protect homes from lightning strikes, with common ‘Hen and Chicks’ varieties of rosette clusters in warm maroons and reds to icy grays or greens. Always excellent in shallow bowls or tubs, when mulched with gravel, smooth pebbles or glass beads, they become extraordinary in massed, combination plantings. Turned loose on a rocky slope, which receives full to partial sun, these succulents can make crazy quilts of colorful textures. One variety of Ever Living Plant that especially appeals to children is the Cobwebs Plant (Sempervivum arachnoideum) with its oddly webbed clumping rosettes and multiple babies.
Another star in the family is Kalanchoe, which sports leaves smooth to hairy in texture, with toothy margins to scalloped edges, and in colors ranging from pinks, reds, greens, blues and silvers. Kalanchoe grandiflora shines as a groundcover, which can thrive even under trees. For colder areas, consider Stone Crops (Echeveria), many of which originated in the mountains of Central and South America. They do well in cold if kept dry and well-drained and can brighten sheltered outdoor areas, along buildings and walls. Echeveria undergo seasonal color change, from mauves, oranges, pinks and greens, and produce dainty, bell-shaped flowers held above the foliage. Try Echeveria ‘Afterglow,’ bright with large mauve leaves outlined in red, with deep crimson flowers. For something whimsical, try an Echeveria with heavily frilled, pink or red-edged leaves, such as ‘Crinoline,’ ‘Cinderella,’ ‘Party Dress,’ ‘Blue Butterfly,’ or ‘Easter Bonnet.’ Strikingly different, experiment with Echeveria ‘Black Prince,’ which attains an ebony hue when grown in bright light. Problem-solver varieties include E. elegans, a stubby, blue-green variety which spreads quickly and blushes pink when stressed by drought, like the tough E. imbricata, which performs well with little care.
Sedums also claim the Crassula family, with more than 800 types under cultivation, historically used for medical applications from fever to scurvy, gout to heartburn. In garden settings, Sedum, such as the resilient and colorful blue and purple-tinged S. commixtum, present effective backdrops for showcasing larger leaved plants. Attractive garden “blankets” can be made with Sedum pachyphyllum, red-tipped blue-gray leaves with yellow, star-shaped flowers, or with the Jelly Bean Plant (Sedum x rubrotinctum)whose stubby red leaves spiral around the stems. Pink-flowered Autumn Joy (Sedum herbstfreude)or Sedum sieboldii, along with scarlet-blossomed Munstead Red (Sedum telephium)make reliably attractive plantings. For something fun in hanging containers, plant Burro’s Tail (Sedum morganianum)or Baby Burro’s Tail (Sedum burrito), plants which trail over edges like living ropes with pink or wine-red flowers in spring.
Graceful Aeonium, while not as frost-tolerant as some in the Crassula family, develops boldly branching rosettes which tolerate drought conditions. The popular ‘Schwartzkopf’ (Aeonium atropurpureum), when grown in strong light, has deep maroon leaves. Equally showy is ‘Tri-color,’ (Aeonium decorum tricolor), with variegated yellow and green leaves edged in bright red. An easy-to-propagate favorite, Aeonium subplanum, has deeply green, flattened rosettes and sprouts multiple plantlets on its stems ready for cutting. For attractively tidy bunches of geometric crowns in the garden, plant Aeonium undulatum pseudotabulaeform, hard to say, but simple to grow.
Why grow succulents? With diverse form, color and texture, they present creative drought-tolerant solutions in multiple settings. Generally easy to propagate, some simply need stem cuttings to dry (“heal”) before planting. When given good drainage, they can thrive. Even in wetter conditions, they may do well if given porous soil mixes, or if planted on sunny slopes. Planting is best done in warm spring or autumn, in wide, shallow holes, with slight mounding in the hole’s center to allow the short roots to spread out. If you remember that succulents in the Crassula family like to dry out before watering, you should get on beautifully together.
To learn more about plants with low water needs, please come to the Master Gardener “Drought-Tolerant Plants” seminar with Richard Ward of the Dry Garden in Oakland. The event is on Thursday, March 6th, Social Hour 6:30-7:30 p.m., Seminar 7:30-9:00 p.m. at the Marin Art and Garden Center, Livermore Pavilion, 30 Sir Francis Drake Blvd., Ross. For information call (415) 455-5263. $5 donation at the door.
Webmaster Email: banielsen@ucanr.edu