Gardeners like to know precisely what they’re planting and expect everything to be labeled by variety. But in the mass-market world of succulents, details such as species, cultivar or even any appellation are often elusive. These are plants sold, after all, as party favors and boutonnieres. Here are a few common types used in container gardens, most of them tender.
Aeoniums are valued for the way their rosettes remain intact — they don’t open up the way sedums do — but they do elevate their leaves on stems as they age. Some varieties come in shades of purple and add a contrast to the planting. The darkest is Zwartkop. The variety Sunburst is a variegated green-and-yellow form with pink edging to the leaves.
The poster plant of aloes is the Aloe vera, favored for its herbal uses, but other species work well in pots and containers. Look for dwarf varieties developed for succulent combinations.
The Agave americana is an enormous and bizarre succulent in tropical gardens, but it will work as a much smaller and slower-growing agave in a container. Agaves have hazardous spines on their leaf tips and must be placed with care. Luis Marmol, gardener at Dumbarton Oaks, likes to grow a thornless species with softer, broader leaves named Agave attenuata. A smaller variety of it named Arboleda Blue grows to four feet or less and is thus easier to bring in on a frosty night, he said.
These are among the largest succulents for container growing, with a profusion of fleshy, paddle-shaped leaves. Some varieties have a thin red edging to the gray-silver leaves. Silver Peak and Silver Storm are popular varieties, the latter having bigger leaves. Both grow to about 20 inches. Give them the space they need or plant them as specimens in their own pots.
Echeveria are rosette types that are often confused with the hardy houseleeks. The rosettes are fuller and come in a beguiling array of colors that range from silver-blue to rose and gray. As a bonus, they produce delicate blooms on a sculptural, wiry stem. One of the most common varieties — Perle von Nurnberg — is also one of the most beautiful: large, rose-purple and with enormous presence in any composition. Topsy Turvy is silver-blue and curly, and Morning Light is a warm mauve. Some varieties have ruffled edges, like lettuce, and varieties of Echeveria secunda multiply to form dazzling rhythms of texture. Echeverias do best in partial shade in our region.
Several euphorbia species have a place in the succulent garden, but the most useful is probably Sticks on Fire, Euphorbia tirucalli. With its coral-like vegetation, it provides a sculptural counterpoint to all other succulents. In its arid, tropical element, it can grow eight feet high or more, but it will stay suitably stunted in a container in these parts, especially if treated as an annual and discarded at season’s end.
Haworthias are similar to agaves and aloes, except they stay small and compliant. They are downright handsome in their sculptural forms. Some radiate flat foliage, others are distinctly upright, and all are architectural. Variegated forms add another layer of ornament.
This is an upright, ribbed and cactuslike succulent useful as a vertical accent in a container composition. The most common species is Huernia zebrina, remarkable for its odd-looking flowers, perfect red-brown hoops surrounded by striped stars.
The common potted plant version is Kalanchoe blossfeldiana, but other species are more suited to the succulent composition, as an accent plant in contrast to the rosette forms. Also, they produce an effective display of dainty flowers held aloft on wiry stems. Look for Kalanchoe pumila varieties such as Silver Gray. Kalanchoe orgyalis has unusual gray-tan foliage good for contrast and is often sold as the variety Copper Spoons. A number of the panda plant Kalanchoe tomentosa varieties have fuzzy foliage with brown edging that looks almost like singeing. One of the most striking types is the flapjack kalanchoe, Kalanchoe luciae, whose leaves are green and rose, grow larger by the month and by season’s end resemble vertical clusters of pancakes. It is effective in large pots but will soon overpower a small, crowded composition.
With more than 300 species, sedums are an astonishingly diverse bunch of plant cousins. The cascading donkey tail (Sedum morganianum) acts as a trailing “spiller” in a container, though its leaves are quite keen to fall off if brushed. You are more likely to find the fleshy rosette forms easier to place, such as the silver-blue Aurora Blue, the gray-pink Sedum carnicolor and the orange-and-green Sedum nussbaumerianum. The diminutive and golden Sedum makinoi Ogon makes a great filler, as does the wispier Sedum mexicanum. Look too for Sedum rupestre Angelina, with its upright, fine growth and the bonus of slender yellow blooms in early fall. If you want absurdly fleshy, berrylike leaves, go for related graptopetalums and pachyphytums.
Sempervivums, or houseleeks, include the stalwart hens and chicks of cottage gardens and are among the hardiest of succulents. Most will survive winters if given excellent drainage and a sheltered location. In containers, they function as low-growing fillers and will increase in size. One species, Sempervivum arachnoideum, produces fine, cobweb-like hairs in its rosettes.
Sources: Succulents are ubiquitous, and because they are so hard to kill, they can be found for sale at a range of retailers, including grocery stores, home decor shops and mass merchandisers. Some independent garden centers in the Washington metropolitan area have good selections of succulents and are more likely to offer a wider range of plants with varietal labeling.
If you want many succulents at bargain prices, look for online retailers such as the Succulent Source, which specializes in mass succulents for the wedding and event-planning trades. Small two-inch plants are economical, even with shipping charges, and will grow quickly in optimum conditions. Cuttings are the cheapest but will need to be rooted indoors before planting.
Chat Thursday at noon Join Higgins for a live Q&A about gardening.