ZZ Plant Care: Light, Watering, Yellow Leaves, and Repotting

A ZZ plant (Zamioculcas zamiifolia) grows best in bright, indirect light but tolerates low light, and it needs very little water: let the potting mix dry all the way through, then water thoroughly and let the pot drain. Use a fast draining mix in a pot with a drainage hole, keep it in a room between about 60 and 80°F, and feed only a few times while it is growing. Yellow leaves and soft stems almost always mean too much water. ZZ plant contains calcium oxalate crystals, like its relatives in the arum family, so keep it away from pets and children who might chew it.

Why ZZ plants are so forgiving

A ZZ plant grows from thick, potato like underground stems called rhizomes, which store water and food. That stored water is why a ZZ can go weeks without watering, shrug off a missed watering, and handle the dry air of homes and offices. It is also why overwatering is the main way people lose one: rhizomes that sit in wet mix rot. Glossy, upright stems with neat rows of leaflets are a sign the plant is happy.

Light

ZZ plants are famous for coping with low light, and they will live for years in a dim office or a hallway. Growth in low light is slow, though, and new stems may lean toward the nearest window. In bright, indirect light, such as a few feet from an east or west window, they grow faster, push up more new stems, and keep a deeper green. Avoid hot direct sun through a south or west window, which can yellow or scorch the leaflets. A ZZ that has been in a dark corner should move to brighter light gradually over a week or two.

In a room with no window at all, a grow light on a timer for 10 to 12 hours a day keeps a ZZ growing.

Watering

Water only when the mix is dry all the way down, not just at the surface. Push a finger or a wooden skewer deep into the pot, or use a moisture meter. When it is fully dry, water slowly until it runs out of the drainage hole, then empty the saucer. In a bright, warm room that is often every two to three weeks. In low light or cool rooms it may be a month or longer. When in doubt, wait a few more days.

Slightly wrinkled or curling leaflets, or stems that start to lean on a plant with bone dry mix, mean it is ready for a drink. Mushy stems, a sour smell, or yellowing at the base of several stems on a plant in wet mix mean the opposite.

Why ZZ plant leaves turn yellow

• Overwatering. By far the most common cause, especially when several stems yellow from the base at once. Stop watering, let the mix dry completely, and check the rhizomes. Firm, pale rhizomes are healthy. Soft, brown, or smelly ones are rotting and should be cut away before repotting in fresh, dry mix. Our guide to root rot in houseplants covers the rescue steps.
• Old stems aging out. One older stem yellowing while new stems come up is normal.
• Too much direct sun. Pale, yellow, or bleached patches on the side facing a sunny window.
• Cold. Temperatures below about 45°F, or leaves touching frosty glass, can yellow and damage the leaflets.

Cut fully yellow stems off at the soil line. They will not turn green again. Our guide to yellow leaves on houseplants explains how to tell the causes apart.

Soil and pots

Use a fast draining mix. A cactus and succulent mix works well, or a general indoor potting mix with about one third perlite added. A pot with a drainage hole is essential. Clay pots dry faster than plastic and are a good choice for anyone who tends to overwater, and their weight helps balance a tall, top heavy plant.

Repotting and dividing

ZZ plants grow slowly and like to be snug, so most need repotting only every two to three years. Repot when the rhizomes press against the sides, crack a plastic pot, or push the plant up out of the mix. Move up only one or two inches in pot width, keep the rhizomes at the same depth, and wait about a week before watering so any damaged roots can heal.

Repotting is also the time to divide a large plant. Gently pull or cut the clump into sections, each with several stems and its own rhizomes, and pot them separately. Single leaflets or stems can also root in water or mix, but they are very slow and may take many months to form a new rhizome and shoot.

Temperature and feeding

Normal room temperatures suit ZZ plants. Keep them above about 50°F and away from cold drafts, doors that open to the outdoors, and heat vents. They need little fertilizer. Feed with a balanced liquid houseplant fertilizer at half strength every month or two while the plant is pushing out new stems, and skip feeding when growth slows in cool, dim months.

Pests and cleaning

ZZ plants have few pest problems. Dust dulls the glossy leaflets, so wipe them with a damp cloth every few weeks, which also lets you spot mealybugs or scale early. Skip leaf shine products, which can clog the leaf surface. If you do find pests, our guide to mealybugs and scale on houseplants explains how to treat them.

Pet and child safety

All parts of a ZZ plant contain calcium oxalate crystals that can irritate the mouth, lips, and stomach if chewed, causing drooling, pawing at the mouth, or vomiting in pets. Place it where pets and small children cannot reach it, and wash your hands after handling cut stems or rhizomes. If a pet chews a plant, call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435. If a child eats part of a houseplant, call Poison Control at 1-800-222-1222.

Bottom line

Give a ZZ plant bright, indirect light if you can, a fast draining mix in a pot with drainage, and water only after the mix is completely dry. Overwatering causes most problems, so check the rhizomes when stems turn yellow, repot only when crowded, and divide large clumps to make new plants.

Related reading

• Snake plant and ZZ for low light rooms
• Low mess houseplants
• Soil moisture meters for houseplants
• Jade plant care: light, water, and pruning

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