String of pearls

About String of pearls

String of pearls is a trailing succulent from the dry eastern Cape of South Africa, where it creeps under bushes and rocks and roots wherever a stem touches the ground. Each pea-sized leaf has a translucent 'window' that lets light in, and the thin stems spill 1-3 ft over the edge of a hanging basket (NC State, Wisconsin Horticulture). It is grown for the look, not for toughness: it rots fast if overwatered, scorches in hot sun, and old plants die back after a few years, so keep cuttings going.

Hardy outdoors only in zones 9b-12 (NC State); it is grown indoors everywhere and can summer outdoors in bright shade, sheltered from rain, once nights stay above about 50 F, coming back in well before frost (NC State, Wisconsin Horticulture).

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Bought as a nursery plant in a hanging pot, or started from a 3-5 in stem cutting laid on moist mix; seed is rarely sold (NC State, Wisconsin Horticulture).

Growing it indoors

• Light: Give it the bright light of an east or lightly curtained south window; direct hot sun scorches the beads, and in too little light the stems go thin and bare (NC State, Wisconsin Horticulture).
• Water: Water thoroughly, then let the mix dry out completely before watering again; the beads shrivel slightly when it is thirsty, which is your cue (Wisconsin Horticulture). Overwatering and root rot are the usual cause of death, so water much less in winter when it barely grows, and never let it sit in a saucer of water.
• Humidity: Ordinary dry room air suits this desert plant; it doesn't need misting or a pebble tray.
• Temperature: NC State gives 70-80 F in summer and a cool 50-60 F winter rest (Wisconsin says 55-60 F); it can't take frost, so bring it in before the first fall frost.
• Feeding: Feed lightly once in spring with a diluted liquid houseplant fertilizer, about once a year (Wisconsin Horticulture); NC State gives no feeding advice.
• Repotting: Repot every year or two into a shallow pot only a little wider, with fresh fast-draining mix (Wisconsin Horticulture); older plants are best replaced with fresh cuttings rather than repotted.

Soil

A very well-drained cactus mix, or potting mix cut with up to half sand, perlite, pumice or poultry grit, in a shallow clay pot that dries quickly (NC State, Wisconsin Horticulture).

Pot in a very well-drained cactus mix, or potting mix cut up to half with sand, perlite, pumice or poultry grit, in a shallow clay pot with a drainage hole (NC State, Wisconsin Horticulture).

Feeding

• Spring, as growth restarts: diluted liquid houseplant fertilizer. Feed lightly once, about once a year (Wisconsin Horticulture); water first so the roots are moist.
• Summer through winter: none. No further feeding; it grows slowly and rests cool and dry in winter (Wisconsin Horticulture).

Rich mix and frequent feeding make soft growth that rots; the real killer is water, not hunger (Wisconsin Horticulture, NC State).

Varieties (1)

NC State names one cultivar.

Pests to watch for

Mealybugs, Aphids, Whiteflies, Fungus gnats

Diseases and problems

Root and crown rot

In the kitchen

Safety: NC State rates it low severity: the leaves and sap contain pyrrolizidine alkaloids, eating the beads can cause vomiting and diarrhea, and the sap can cause a skin rash, so wear gloves when you take cuttings and keep it out of reach of small children.

Pets: Toxic (ASPCA): the ASPCA's succulent guide says string of pearls causes stomach upset, mostly vomiting, and lethargy if eaten; NC State lists it as a problem for dogs, cats and horses.