Why are my ZZ plant leaves turning yellow?
A ZZ plant hardly ever complains, so a yellow leaflet is alarming. Sometimes it is just the plant renewing itself; sometimes it is a warning from under the soil.
A ZZ plant with yellow leaves is almost always getting too much water: the soil stays wet and the rhizomes begin to rot. If it is just one old leaflet low down and the rest of the plant is green and firm, that is normal renewal and there is nothing to fix.
Why does a ZZ plant turn yellow?
The ZZ plant (Zamioculcas zamiifolia) stores water in thick rhizomes below the soil, so it copes with drought far better than with damp. Oklahoma State University Extension warns that those rhizomes rot when the plant is overwatered, and the University of Connecticut goes further: too much water is about the only thing that kills it. Once the roots stop working, the leaves stop getting what they need and turn yellow.
There are other, less common causes:
- Age. The oldest, lowest leaves eventually yellow and drop, one at a time. Most guides treat this as normal.
- Strong direct sun. The University of Florida recommends bright, filtered light with no direct sun. In harsh sun the leaflets can scorch and develop patches that fade to yellow.
- A very long dry spell. According to the same university, in prolonged drought a ZZ sheds its leaflets and keeps the swollen stalk bases as a reserve. That is a survival trick, not a disease.
How can you tell which cause it is?
The pattern of the yellow tells you a lot. Look at the whole plant before you change anything.
- One or two low leaflets, slowly, with green new shoots: age. Snip them off if you like.
- Several stems yellowing at once, damp soil, soft base: overwatering, and probably rot already.
- Dry, bleached patches on the window side: sun.
- Wrinkled leaflets falling off, soil bone dry for ages: thirst, which is rare.
The real test is the soil. Push a finger or a wooden skewer halfway down the pot: if it comes out damp while the plant is yellowing, you have your answer.
Can low light make a ZZ plant yellow?
Not directly, but it sets up the problem. ZZ plants are famous for tolerating dim corners, yet there they drink very little, and a “normal” watering in a dark spot leaves the soil wet for weeks. See how the gap between waterings changes from spot to spot:
| Where it lives | In July | In January |
|---|---|---|
| South- or west-facing window | 7 days | 13 days |
| East-facing window | 8 days | 15 days |
| North-facing window | 12 days | 24 days |
| Hallway or corner with no window | 18 days | 34 days |
If your plant lives far from a window, our guide to the best plants for low light is worth a read too.
How do you save an overwatered ZZ plant?
First, stop watering and empty the saucer. If the stems are still firm, simply let the soil dry right out and water less often from then on.
If any stems are soft at the soil line, take the plant out of its pot. A healthy rhizome is firm and pale; a rotten one is soft and dark. Cut away the rotten parts with clean scissors, let the cuts dry, and replant in fresh, dry, free-draining compost in a pot with a drainage hole. After that, water sparingly and only once the soil has dried.
Stems that have already turned yellow will not go green again. Cut them off at the base; the plant sends up new shoots from the healthy rhizomes.
How do you prevent yellow leaves on a ZZ plant?
- Water by the soil, not the calendar. Only when it is dry halfway down, or nearly all the way. Our guide on how often to water a ZZ plant explains the test.
- A pot with a hole and a light mix, with bark or perlite.
- Bright light, but no direct sun on the leaves.
- Even less water in winter. Growth slows and the soil takes longer to dry.
In short
| What you see | Likely cause | What to do |
|---|---|---|
| One old leaflet, low down | Age | Nothing, or snip it |
| Several yellow stems, damp soil | Too much water | Stop watering, let it dry |
| Soft stems at the base | Rhizome rot | Unpot and cut out the rot |
| Patches on the window side | Direct sun | Move it out of the sun |
| Wrinkled, falling leaflets, dry soil | Long drought | Water thoroughly |
Quick questions
Should I cut off yellow leaves? You can, at the base of the stem. They will not recover, and removing them makes it easier to spot any new ones.
Will fertiliser fix it? Rarely. On a yellowing ZZ the cause is usually water, and feeding a sick root does not help.
Will the plant recover? If firm rhizomes remain, yes: it will shoot again, if slowly.
A plant that rarely warns you
A ZZ plant gives few signals, and by the time it does, something has been wrong for a while. Verdejar helps you avoid getting there: it works out the timing from your light, your pot and the season, and reminds you to water only when it is needed. See also the ZZ plant page.
Sources: University of Connecticut Extension · Iowa State University Extension · Clemson Home & Garden Information Center · UF/IFAS Extension. The days between waterings come from the Verdejar watering engine.