From the rocky parts of the world, where they have strong winds and thin soil, we get tough and colorful plants with rosettes of succulent leaves. These are the sedums and succulents (including hens and chicks), and they need very little fertilizer or water.
Most of these plants need sun, but some are good in partial shade. Their shapes are bold and kind of cute. Some spread by making a ring of little stems with new plants on the ends, all around the parents; the small ones can be replanted with ease. Because they are useful in planters, stone walls, green roofs, green walls and living wreaths, sedums and succulents are trendy right now.
There are warnings. A few sedums, like Golden Acre, are so easy to grow that they’re invasive. Others, though easy to grow in difficult, dry places, will die in rich, moist, deep garden soil—the kind most of our other plants like so much.
You’ll have an easier time with most sedums in places that are more like the rocky slopes where they originated. You can create a dense, colorful tapestry of foliage in varied colors and shapes, seemingly springing out of nowhere—just as you would find in nature.
Unlike cacti, sedums and succulents have no spines, so it’s easy to enjoy their dense, architectural foliage as summer’s bold flowers end with the season. Choose the hardy perennial types for outdoor gardening, or enjoy any of them indoors.
Good drainage is a must. Use prepared cactus soil straight from the bag, or make your own mix. For clay pots or garden troughs, use one part prepared all-purpose potting medium, one part coarse sand or perlite, and one part pea gravel or small pebbles. Clay chips can be substituted for the pebbles. This lean but healthy mixture will keep your plants from growing too fast. Use the small gravel sold for aquariums for a top dressing after planting. The soil layer can be rounded for a more dramatic look.
If planting succulents in the ground, select a free-draining area such as a slope or raised bed. Add lots of coarse sand, clay chips, small pebbles and perlite to lighten the soil. Plant them at the same depth they were growing in the pot. Add offshoots too, if you have them. Top dress with a layer of gravel for a finished look.
Keep the area moist but not soggy. After the plants take hold, they will do well with less water.
When transplanting succulents into dry stone walls, you’ll need a stickier planting mix. The wall itself will take care of the drainage. Mix some heavy clay soil with a bit of fertilizer (old-timers say manure). It should be wet enough to form a dense ball, but not dripping. Take the succulents out of their pots and brush off most of the potting mix, or collect the offshoots from larger plants—the small, young rosettes on their stems (stolons)—and plant them. Clean off old brown leaves.
Cover the roots or stem bottoms with a bit of this clay mixture, and poke them into the crevices of the wall. Work the roots of the succulents in as far as possible, poking in more of the clay mixture without breaking the stems. The succulents should quickly take hold and establish themselves.
People deliberately create planting spaces in walls, planting as they build. You can plant natural crevices in rocky outcrops the same way.
Green roofs need a lightweight planting medium, held in place with mesh atop a waterproof layer above the roof material. Soilless mix, sand, perlite and small clay balls or chips are enough. Use only the smallest and toughest types of succulents. Hens and chicks (houseleeks) were used on rooftops as a fire retardant. [pullquote]Give some of these special plants a place in your garden.[/pullquote]
The roof should not retain water or be too heavy. Maintenance is tricky. At the Morris Arboretum near Philadelphia, the horticulturist uses a harness system in case of a fall. My advice: Just make a birdhouse or garden shed a green roof, unless you’re calling in the experts.
Here are some great hardy succulents. I like the paved-with-plants look.
Hens and chicks, also called houseleeks and sempervivums. These hardy plants make fat rosettes surrounded by smaller ones on stolons. The foliage of Mars is green tipped with red. Sempervivum atlanticum has a pink edge on the leaves. Sempervivum arachnoideum has small rosettes within a network of white fibers. Sempervivum
Pink Flamingos are bright pink with green tips, while Sunset has a mixture of tones. Cmiral’s Yellow really is yellow. Jovibarbas resemble Sempervivum species and are equally good.
Sedum species. There are large, small and in-between types of sedums, also called stonecrops. The tallest ones, like Sedum Autumn Joy, resemble broccoli until the pink flowers open. Similar types have purple or variegated foliage. A new one is Purple Emperor. Sedum spathulifolium is smaller. It comes in green, red, or chartreuse and makes a goodlooking groundcover mat. Sedum rubratinctum has jellybean-shaped, rounded leaves and comes in green, pink, yellow or red. It’s petite and makes a nice mat in flowerpots or troughs. Sedum ternatum is in between. It’s a North American native plant and grows in moist places in shade to partial shade. It makes mats of juicy green foliage and blooms with white flowers in spring.
There are hundreds of types with amazing forms and colors. Shop in person or from a well-illustrated catalog, and give some of these special plants a place in your garden. Maintenance is simple. Remove weeds, spent flowers, and spoiled leaves, and tuck in a few new chicks wherever any gaps appear.