Plant care guide
ZZ Plant Brown Spots: Sun Scald, Wet Roots or Leaf Spot?
Updated · First published
Why does my Zz plant have brown spots?
Brown spots on a ZZ plant most often come from direct sun scalding the leaflets, or from mix that stays wet and damages the roots and rhizomes. Small brown spots with yellow rims, or water-soaked spots, point to a leaf spot disease.
What to do first
Look at where the spots are and feel the mix. Move a scorched plant out of direct sun. Let a wet pot dry and check the rhizomes. Remove spotted leaflets and keep water off the foliage if the spots look like a disease.
ZZ plants (Zamioculcas zamiifolia) rarely have problems. Iowa State University Extension calls the ZZ plant tough and easy to grow, with few insect or disease problems. So brown spots usually mean a care or placement problem. Leaf spot disease is possible but less common.
The spot’s position, shape and the state of the mix point to the cause. Check them before you treat anything.
Match the spots to a cause
| What you see | Likely cause | First check |
|---|---|---|
| Scalded, brown patches on leaflets facing a window | Direct sun scald | Does sun hit the plant, especially in the afternoon? |
| Brown or yellow leaflets, soft or dark stalks near the mix, wet pot | Overwatering and rot | Is the mix wet below the surface? Are rhizomes firm? |
| Small brown spots with yellowish rims, sometimes ringed | Fungal leaf spot | Has water been splashed or misted on the leaves? |
| Water-soaked spots, sometimes with a yellow halo | Bacterial leaf spot | Is the plant crowded, cold or kept wet on the foliage? |
| White or straw-coloured spots after watering | Cold water spotting | Has cold water splashed on the leaves? |
| Raised brown bumps you can scrape off | Scale insects | Do the “spots” lift off with a fingernail? |
Direct sun scald
NC State Extension’s ZZ plant profile warns that scalding and browning of leaves can occur in direct sunlight. Iowa State says direct afternoon sun may damage the foliage. Sun damage shows on the leaflets most exposed to the light and appears soon after a move to a brighter spot.
What to do: Move the plant to bright, indirect light. NC State, Iowa State and UF/IFAS all name bright indirect light as best. Scalded tissue will not turn green again. Trim badly damaged leaflets or stems if you don’t like the look.
Overwatering and rhizome rot
The ZZ plant stores water in thick, underground rhizomes. NC State says wet feet are not tolerated. UF/IFAS’s ZZ plant guide warns that roots left sitting in water may rot. Iowa State says problems develop when the plant is watered too often and the mix stays constantly wet.
Clemson Cooperative Extension’s houseplant disorders factsheet describes root and stem rot. Stems may be girdled at or near soil level by a ring of brown or black tissue. Infected roots are brown to black and may be soft.
What to do:
- Stop watering and feel the mix well below the surface.
- If it stays wet, slide the plant out and look at the roots and rhizomes. Clemson describes rotted roots as brown to black and soft. Keep firm tissue.
- If only a few roots are affected, cut them out and repot in fresh mix. Clemson recommends this approach. Use a pot with a drainage hole.
- Water again only when the mix has dried. NC State advises watering about once a month in winter and twice monthly in summer, only if the mix has dried out completely. Iowa State gives a thorough watering every 7 to 14 days as usually fine. Discard water that collects in the saucer.
For more on reading the rhizomes, see ZZ plant watering.
Fungal and bacterial leaf spots
Clemson describes fungal leaf spots as small brown spots with yellowish margins. They may show a target pattern or tiny black dots. Bacterial leaf spots look water-soaked, sometimes with a yellow halo. Under drier conditions they turn reddish-brown and speckled.
What to do:
- Remove and destroy spotted leaflets or stems.
- Stop misting and avoid splashing water on the foliage. Clemson says splashing spreads leaf spot fungi.
- Give the plant space and good air circulation.
- For bacterial spots, Clemson also advises avoiding low temperatures and crowding.
- Clemson lists copper soap and other fungicide sprays for use after infected parts are removed. Follow the label.
Cold water spots
Clemson notes that watering with cold water or splashing it on leaves can cause white or straw-coloured spots on some plants. Water at the base with room-temperature water.
Scale insects
NC State names scale insects as the pest to watch on ZZ plants. Clemson’s houseplant pests factsheet describes scales as small, immobile bumps on stems and leaf undersides. Some look like fish scales stuck to the plant. Early infestations can be scraped off with a fingernail. Isolate the plant while you deal with them.
Keep new spots from forming
- Bright, indirect light, with no direct afternoon sun.
- Water thoroughly, then let the mix dry before the next watering.
- Use a pot with a drainage hole and empty the saucer.
- Keep water off the leaves.
- Check stems and leaf undersides when you water.
Older leaflets with spots will not heal, but new stems should come in clean once the cause is fixed. For full care, see our ZZ plant care guide.
Related guides
Other zz plant problems we cover: mealybugs, fungus gnats.
References
How this guide was put together: NC State Extension, UF/IFAS Extension, Iowa State University Extension and Clemson Cooperative Extension guidance.