ZZ plants (Zamioculcas zamiifolia) are known as some of the easiest houseplants around — and for a good reason. Not only do these hardy and symbolic plants thrive in a range of soil, temperatures, and humidity conditions, but they can also tolerate low light and don’t require much fertilization. But even these extremely low-maintenance plants occasionally have problems, usually due to over-watering. This guide will take you through everything you need to know about the most common causes of ZZ plant leaves turning yellow or brown and how to remedy the problem at home.
Common Reasons ZZ Plant Leaves Turn Yellow
The most common cause of yellow leaves on a ZZ plant is due to over-watering. If ZZ plants are allowed to stand in water or left in too-wet soil, they may develop yellow leaves and root rot. Pests are rare but may include aphids and spider mites. Other yellow ZZ plant foliage causes include over-fertilization or direct sun exposure.
8 Common Causes of ZZ Plant Leaves Turning Yellow
By far, the most common cause of ZZ plant leaves turning yellow or brown is due to over-watering. ZZ plants are very drought tolerant and usually only need watering once every two weeks during the active growing season, the spring and summer. During the rest of the year, ZZ plants usually only need to be watered about once a month.
Because they’re semi-succulents, ZZ plants can grow in dry and even drought-like conditions. They store water in their fleshy leaves, as well as their tuberous rhizomes. The plants grow in semi-arid conditions in their native habitat of eastern Africa, Tanzania, Kenya, and South Africa.
When they receive too much water, the plants may respond with yellowing foliage, drooping, mushy stems, or browning. Prevent this problem by watering only when the soil feels dry to several inches down. Ensure the plant is in a pot with adequate drainage holes; terra cotta is a good choice for ZZ plants. Use potting soil that contains sand to help with drainage.
Prevent root rot by watering infrequently and using pots with adequate drainage. Avoid placing gravel or rocks at the bottom of the plant’s container, and never use soil from your garden or re-use potting soil from other plants. Pot ZZ plants in a well-draining, pasteurized potting mix.
ZZ plants can tolerate and even prefer, dry conditions. But, like other plants, they still need water to survive. If you notice yellowing, browning, or drooping foliage on your ZZ plant (and the soil is not wet), under-watering may be the cause.
Underwatering may be especially pronounced in the summer, when temperatures are hot. Check for under-watering if your ZZplant is exposed to bright light, or if your plant is placed near a heating vent or register.
Fix the problem by slowly pouring water into your ZZ plant’s soil. If the soil is extremely dry, it may deflect water. Allow the excess to drain through the pot’s holes, then repeat until the soil has absorbed an adequate amount of water. Going forward, water when the top few inches of soil feel dry to the touch.
ZZ plants grow best when they’re placed in spots that receive bright but indirect light or filtered light. This is usually found in an east-facing window, a few feet from a south- or west-facing window, or a south- or west-facing window that remains covered by a sheer curtain. These conditions best mimic the dappled sunlight the plants receive in their native habitat.
While ZZ plants can live for years in low-light conditions, they won’t necessarily thrive or experience optimal growth. You may notice yellowing leaves if the plants don’t receive enough light. Place your ZZ plant in an east- or north-facing window to ensure it’s getting the right amount of light.
If your ZZ plant is exposed to bright direct light, such as often found in a west- or south-facing window, its foliage may turn brown. The afternoon sun may be especially harmful, so protect your ZZ plant from harsh light exposure.
For more, see our in-depth guide on where to position ZZ plants in the home.
ZZ plants don’t require much feeding to thrive. In fact, too much fertilizer can harm your ZZ plant, leading to yellow or brown leaves.
In most cases, your ZZ plant only needs to be fertilized twice yearly, once in spring and once in summer. Wait two months between feedings and use diluted fertilizer.
If your ZZ plant has been in the same container for a long time, the soil may become depleted of nutrients. This may cause foliage damage. Feed the plant using a 5-5-5 or 4-5-4 liquid fertilizer diluted to 1/2 strength, or a 10-10-10 fertilizer diluted to 1/4 strength.
Temperature drops may cause leaves to turn yellow, wilt, and then brown. ZZ plants grow best when the ambient temperature remains between 65 and 85 degrees F. Fortunately, this is a typical range for many indoor spaces.
Any colder, and the plant may suffer damage. Temperatures below 45 degrees F can kill ZZ plants. Keep them away from cold drafts, such as near windows or doors, and away from air conditioning vents.
Similarly, too-high temperatures aren’t suitable for ZZ plants, either. Avoid placing them near heating registers or directly in the south- or west-facing windows where temperatures tend to rise. This can dry soil out too quickly and damage foliage.
ZZ plants grow best when humidity levels remain between 40 and 50 percent. For most homes, this is a typical range.
If humidity is extremely low, you can raise moisture levels in the air by placing your ZZ plant’s pot on a tray filled with pebbles and water. As the water evaporates, it increases humidity levels around the plant.
Remember that overly humid conditions aren’t optimal for these dry-loving plants.
Fortunately, ZZ plants rarely have pest problems. However, you may notice the following:
- Aphids: These insects strip sap from the ZZ plant’s foliage, leaving yellow marks. Treat aphids using mild horticultural soap.
- Spider mites: Often found in dry conditions, spider mites form almost-invisible webs around plants. Isolate the infested plant and use insecticidal soap or treatment to kill the mites.
- Fungus gnats: Fungus gnats thrive in wet soil. Use sticky traps or Mosquito Bits and avoid over-watering.
How to Fix Yellow Leaves on a ZZ Plant
The best way to prevent and fix yellow foliage on a ZZ plant is by providing it with optimal growing conditions that mimic its natural habitat. This includes:
- Bright indirect, or medium light
- Watering only when the top inches of soil feel dry
- Using well-draining potting soil and containers with adequate drainage holes
- Fertilizing infrequently using diluted fertilizer
- The temperature stays between 65 and 85 degrees F year-round
- Humidity between 40 and 50 perfect
- Avoiding over- and under-watering
- Prune any withered stems away periodically.
- Consider repotting your ZZ plant every 2 to 3 years if it has outgrown the current potting vessel.
ZZ plants are considered mildly toxic, so it’s prudent to wear protective gloves when handling these plants for any extended period of time.
Yellowing ZZ Plant Leaves FAQs:
Can yellow or brown ZZ Plant leaves turn green again?
No, yellow or brown leaves will not turn green again. Remove them carefully from the plant.
Can direct sunlight cause ZZ Plant leaves to turn yellow or brown?
Yes, direct sunlight can be too harsh for a ZZ plant. It prefers bright indirect or medium light, such as found in an east- or north-facing window.
Does the type of water cause ZZ Plant leaves to turn yellow or brown?
ZZ plants aren’t overly sensitive and can be watered with tap water. However, rain or distilled water is always a good choice for houseplants.
Can over-fertilizing cause ZZ Plant leaves to turn yellow or brown?
ZZ plants don’t need much fertilizer, and overfeeding can damage foliage. Only fertilizer twice during the growing season, using heavily diluted fertilizer and waiting two months between feeding.
ZZ Plant Leaves Turning Yellow or Brown – The Final Word
ZZ plants are known for their glossy beauty and low maintenance needs. But even these easy-care plants can experience yellowing or brown leaves. Most issues are due to over-watering. Other common culprits are under-watering, overexposure to light, overfertilization, and temperature fluctuations.
If you’re looking for your next ZZ plant to add to your collection, see our in-depth guide to the best plant shops delivering ZZ plants nationwide.
Linsay is an American copywriter based in the Pacific Northwest with a background in academic writing and research. Linsay holds Master's degree in both Anthropology and Library and Information Sciences and has written for numerous national and international publications including USA Today, SFGATE, Hunker, and The Bump across an array of topics in the gardening, green living, and travel sectors. When she's not writing, you'll usually find Linsay reading, kayaking, sailing, snowboarding, or working in her garden.