ZZ plant

Identification and origin

Zamioculcas zamiifolia belongs to the arum family, Araceae, along with peace lilies and monsteras, and is the only species in its genus. The name combines Zamia, an unrelated genus whose foliage it resembles, with calcas, the Arabic name for elephant’s ear (Colocasia); zamiifolia means “with leaves like Zamia.”

It is native to Kenya, Tanzania, Malawi, Mozambique, Zimbabwe and KwaZulu-Natal. There it grows in grassland, dry forest and savanna woodland, where heavy rains alternate with long droughts. That explains how it works: its underground rhizomes, fleshy like tubers, store water and reserves, and its thick, waxy leaves limit water loss.

The plant has no aboveground stem: what looks like a stem is the leaf stalk (petiole) of a pinnately compound leaf that rises straight from the rhizome. Thick, swollen at the base and tapering upward, it stands upright and then arches. A leaf is often 16 in – 2 ft long, sometimes up to 4 ft, and carries six to eight pairs of elliptic, dark green leaflets up to 6 in long, leathery and so glossy they look polished. The overall effect recalls a cycad. Dark spots on the leaf stalks are normal.

Growth is very slow and comes in spurts; the plant reaches its mature size, 2–4 ft tall and wide, in two to five years, and slowly widens as new leaves emerge from the base. It rarely flowers indoors and never in low light: on a mature, well-lit plant, a green spathe wrapped around a creamy white spadix appears at soil level between spring and summer, sometimes followed by white berries.

Cultivars: ‘Raven’, whose green new leaves turn nearly black, rarely exceeds 2.5 ft; ‘Chameleon’ has golden yellow new leaves that mature to dark green; ‘Lucky’ has broad leaflets with rounded tips; ‘Zenzi’ is a dwarf (10–12 in). A cream-variegated form also exists but is harder to find.

Light

It prefers bright but indirect light, which speeds up growth. It tolerates dark rooms, even a windowless office with a few hours of artificial light a day, though it grows more slowly there; after a long spell in light that is too dim, it declines and may suddenly collapse.

Avoid direct sun, especially in the afternoon: it bleaches, yellows, curls and browns the leaflets in patches and can kill back whole leaves. Outdoors in summer, choose shade, partial shade or morning sun only.

Watering

Treat it like a succulent: its rhizomes carry it through long dry spells, while soil that stays wet makes them rot.

From spring to fall, wait until the potting mix is completely dry, deep down and not just at the surface. Then water thoroughly, ideally in the morning and with tepid water, until it runs out of the drainage holes, and empty the saucer after about 15 minutes. In winter, when growth slows, water much less often.

There is no fixed schedule: it all depends on light, warmth, the pot and the mix, and in a dim, cool corner it uses far less water. What to watch for: yellowing leaves and leaf stalks that soften at the base point to too much water; after a long drought, the plant sheds its leaflets and the tips of its leaf stalks, sometimes all of its foliage, and lives off its rhizomes.

Ordinary household humidity is enough; there is no need to mist.

Potting mix

In the wild it grows in sandy, poor soil. In a pot, use a well-drained mix based on peat, coir or bark, for example half potting soil, a quarter perlite and a quarter sand, in a pot with drainage holes.

It needs little feeding: a balanced fertilizer diluted to half strength, once or twice during spring and summer, is enough. None in winter.

Temperature

It grows best between 70–84 °F, and faster the warmer it is. Keep it above 61 °F: below 50 °F, growth slows and damage can occur, and it does not tolerate frost. Keep it away from air-conditioning and heating vents.

A plant moved outdoors to a sheltered spot for the summer should come back in during fall once temperatures fall below 61 °F. In the ground it is grown only in USDA zones 9–10, in partial to full shade.

Repotting

Rarely needed. Repot in spring once the rhizomes fill or distort the pot: their pressure can even crack it. Choose a pot only slightly larger, with drainage holes; an oversized pot stays wet too long and encourages rot. The sap irritates skin and eyes, so wear gloves.

Pruning

No pruning is needed. Remove faded, yellowed or damaged leaves and spent flowers at soil level.

Propagation

• Division: the most common and fastest method. When repotting, separate sections that each have leaves, a piece of rhizome and enough roots.
• Leaf or leaflet cuttings: slower but more productive. Take a whole leaf or individual leaflets, let the cut dry for a few hours to a few days, then push the base into a moist soilless mix or stand it in water, somewhere warm (around 81 °F) and humid. Roots appear first, then a small rhizome. Expect about a month in a greenhouse and up to nine months in a home. Cuttings from the tip of a leaf form the most rhizomes; a leaf stalk without leaflets will not root, while a fallen leaflet can.

Common problems

• Mushy leaf stalks, rotting rhizome, collapsing plant: overwatering or poor drainage, especially when cool; this is the leading cause of loss.
• Yellowing leaflets: often too much water, sometimes direct sun or an old leaf being replaced; check whether it is isolated or widespread.
• Dropping leaflets: a very long dry spell.
• Dry brown patches, bleached or curled leaflets: sunburn, even behind glass.
• Plant that weakens, then collapses: prolonged low light; a cold snap below 50 °F also damages the foliage.
• Pests: uncommon, but watch for scale, mealybugs, aphids, thrips and whiteflies.

A single symptom can have several causes: look at watering, light and temperature together before acting.

Toxicity

The plant is toxic to cats, dogs and people, with medium severity. It contains calcium oxalate crystals that, when chewed, painfully irritate the mouth and throat; eating leaves in quantity can cause vomiting and diarrhea. The sap irritates skin and eyes, so wear gloves when handling it and wash your hands afterward. Keep it out of reach of children and pets; if any part is swallowed, contact a veterinarian or Poison Control.