Sedum

Sedum, commonly known as stonecrop, is a large, cosmopolitan genus of leaf succulents in the family Crassulaceae, ranging from tough, mat-forming garden groundcovers to tender, trailing houseplants. With hundreds of species spread across the Northern Hemisphere — and a scattering into the Southern — it is one of the most familiar and beginner-friendly groups of succulents in cultivation.

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The common name "stonecrop" reflects the way many species colonise rocks, walls, gravel and other stony, nutrient-poor ground where little else will grow. Botanically the genus is a sprawling and somewhat artificial assemblage, and taxonomists have progressively split off segregate genera (such as Hylotelephium, Phedimus, Petrosedum and Rhodiola) from the traditional broad concept of Sedum. For the grower, however, the plants sold under this name share a common set of easy, forgiving habits.

Description

Sedums are perennial (occasionally annual or biennial) succulents with fleshy leaves that store water, allowing them to endure drought and poor soils. Beyond that, the genus is remarkably variable. Leaves may be tiny and bead-like, flat and paddle-shaped, or cylindrical and jelly-bean-like, and they are arranged in rosettes, along creeping stems, or densely packed like beads on a string. Growth habit ranges from ground-hugging mats a few centimetres tall to shrubby or pendent stems that spill from a hanging pot.

Flowers are typically small and star-shaped, usually with five petals, and are borne in branching clusters. They come in white, yellow, pink and red, and in many species are abundant enough to smother the foliage and draw in bees and other pollinators. Like most Crassulaceae, sedums use CAM photosynthesis, opening their pores at night to conserve water — part of what makes them so tolerant of dry conditions.

Distribution

Sedum is genuinely cosmopolitan, with the great majority of species found across the temperate and mountainous regions of the Northern Hemisphere. There are notable centres of diversity in Mexico, eastern Asia and the Mediterranean, along with many species scattered through Europe, North America and North Africa. Habitats are typically open and exposed — rocky outcrops, cliff faces, screes, dry grassland, old walls and roofs — where the plants' drought tolerance lets them thrive in thin, fast-draining soils.

This wide range explains the split in hardiness that growers encounter: species from cold mountain and temperate zones (such as Sedum spurium and Sedum acre) are frost-hardy garden plants, while those from warmer regions like Mexico (such as Sedum morganianum) are tender and grown as houseplants or under cover.

Notable species

Sedum morganianum — burro's tail; a tender Mexican species with long, trailing stems of plump blue-green leaves, popular as a hanging plant.
Sedum rubrotinctum — jelly bean plant or pork and beans; bead-like leaves that flush red in bright light and strong sun.
Sedum spurium — a hardy, mat-forming groundcover (now often placed in Phedimus), widely used in rockeries and on green roofs.
Sedum acre — biting stonecrop; a tiny, tough, yellow-flowered species that colonises walls and gravel.
Sedum dasyphyllum — a diminutive, blue-grey cushion of rounded leaves, prized in miniature and trough plantings.
Sedum nussbaumerianum — coppertone stonecrop; rosettes that turn warm orange in good light.
Sedum adolphii — golden sedum; sun-loving golden-green rosettes, a common windowsill plant.

Many former sedums are now classified elsewhere — the tall, clumping "border stonecrops" such as Sedum 'Autumn Joy' belong to Hylotelephium — but they are still very often sold and discussed under the Sedum name.

Cultivation

Sedums are among the easiest succulents to grow, which is a large part of their appeal. Almost all want plenty of light — bright indirect light indoors, or full sun to part sun outdoors — and a fast-draining, mostly mineral mix. Water thoroughly when the soil has dried out, then let it dry again; err on the side of underwatering, as the fleshy leaves carry the plant through dry spells and soggy roots quickly lead to rot. See Watering for general technique.

The key distinction for the grower is hardiness. Cold-tolerant species make excellent, low-maintenance outdoor groundcovers, rockery plants and green-roof cover, shrugging off frost and neglect. Tender species such as Sedum morganianum need to be kept above freezing and are usually grown in containers or as houseplants, moved under cover for winter. Good light keeps all of them compact and well-coloured; grown too dark, stems stretch and pale (see Common problems, below). Repot crowded or top-heavy plants into a snug container as needed — see Repotting.

Colour in many species is light-driven: leaves that are green in shade blush red, orange or amber under strong sun and cool nights. A period of bright, cool, dry conditions also encourages the best flowering.

Propagation

Sedums are famously easy to propagate, which makes them great plants to share. Most species root readily from:

Stem cuttings — snip a length of stem, let the cut end callus for a day or two, and lay or plant it on barely moist mix (see Propagation — cuttings).
Leaf cuttings — many sedums will sprout a new plantlet from a single fallen or detached leaf laid on the soil surface.
Offsets and division — clumping and mat-forming kinds can simply be pulled apart and replanted (see Propagation — offsets).

Fine seed is also produced and can be raised on a mineral surface (see Propagation — seed), though for named plants vegetative methods keep the parent's exact traits. Trailing species like burro's tail drop their beads at a touch — a nuisance when handling, but every dropped leaf is a potential new plant.

Common problems

Rot — the commonest cause of loss, almost always from overwatering, poor drainage, or standing water on the leaves; stems and leaves go soft, translucent and brown.
Etiolation — too little light stretches the stems and spaces out the leaves, and colourful forms revert to plain green; move to a brighter spot and propagate the leggy tips.
Leaf drop — some species (especially Sedum morganianum) shed their plump leaves at the slightest knock; site them where they won't be brushed against.
Pests — mealybugs (white fluff in the leaf axils) and aphids (often on soft new growth and flower stems) are the usual offenders; see Pests and diseases.

References

Horticultural information for growing these plants as ornamentals. Always confirm plant identification and any handling, grafting, or safety advice against authoritative sources before acting.