ZZ plants are sold as hard to kill, and mostly they are. The one thing they handle badly is mix that never dries. Clemson Extension’s care tips put it first: do not overwater, and do not let the plant sit in water.
A calendar cannot tell you when the mix has dried. Light, warmth, pot size and mix all change that. This guide explains why the ZZ copes with dry spells, what the extension services recommend, and how to check before you pour.
Why a ZZ can wait
Zamioculcas zamiifolia grows from thick, underground rhizomes. NC State Extension describes bulbous, fleshy rhizomes that store water and make the plant highly drought tolerant. Clemson calls them bulbous rhizomes that store water.
Its home climate explains the design. Illinois Extension says the ZZ comes from East Africa, where heavy rain alternates with prolonged drought. The rhizomes store water and nutrients, and the thick, waxy leaves limit water loss.
That storage is also why the ZZ dislikes constant moisture. Illinois says it is intolerant of sustained soil moisture. NC State says wet feet are not tolerated, and that the plant can be treated much like cactus and other succulents.
How often: what the sources say
| Source | Advice |
|---|---|
| NC State Extension | Water routinely but let the mix dry out between waterings. About twice a month in summer, only if the soil has dried out completely. Once a month in winter. |
| Clemson HGIC | Water 1–2 times a month, only after the potting medium has completely dried. |
| Illinois Extension | Water routinely, letting the soil dry between waterings. Reduce to once a month in autumn and winter. |
| Iowa State Extension | Keep on the dry side. Water thoroughly, then let the mix dry nicely. In most cases every 7 to 14 days is fine. |
| UF/IFAS EP480 | Do not let the plant sit in water. Allow the soil to become dry between waterings. |
The frequencies differ because conditions differ. The rule they share is the important part: water thoroughly, then wait until the mix has dried. Iowa State warns that problems develop when the plant is watered too often and the mix stays constantly wet.
How to check before you water
Virginia Cooperative Extension says most houseplants do not need a rigid schedule, but they do need frequent checks. For a ZZ:
- Feel the mix. Push a finger in. Virginia suggests checking 2.5–7.5 cm (1–3 in) deep, depending on pot size. For a ZZ, NC State and Clemson want the mix dry, not just the surface.
- Lift the pot. Virginia notes a very light container is a sign of dry mix. Lift it after watering so you know the full weight.
- Look at the mix edge. Dry mix can shrink away from the pot wall, which Virginia lists as an underwatering sign.
If the mix is still damp, wait and check again in a few days.
How to water
- Water thoroughly. Iowa State says water should flow out of the bottom of the pot.
- Discard the excess. Iowa State and Clemson both say not to let the plant sit in water. Clemson adds: make sure the pot has fully drained before you set it back in a decorative pot or saucer.
- Re-wet mix that sheds water. Virginia Cooperative Extension explains that very dry peat- or bark-based mix can become hydrophobic and let water run straight through. Give two or three slow applications, or bottom water for 15 to 30 minutes, never more than 60.
- Wait for the dry-down. Then check again.
Is it thirsty or overwatered?
Wilting does not settle it. Virginia Cooperative Extension says wilting is the first symptom of both problems.
| Check | Points to thirst | Points to overwatering |
|---|---|---|
| Mix | Dry, shrunk from the pot edge | Wet for days, may smell rotten |
| Pot | Very light | Heavy |
| Leaves | Dry or brittle, brown edges, leaflets dropping | Yellowing on new and old leaves, leaves dropping |
| Stems | Upright or wilting | Soft or mushy, especially at the base |
| Other | Stunted growth | Fungus gnats, stunted growth |
These are Virginia Cooperative Extension’s general houseplant symptoms. For the ZZ specifically, UF/IFAS notes that the plant is very drought tolerant but leaf drop may occur. Outdoors in drought, it says the leaflets and upper leaf stalk fall off, leaving the swollen stalk base to carry the plant until the next rain. So dropping leaflets with bone-dry mix after a long gap point to thirst.
Soft, collapsing stems with wet mix point the other way. University of Maryland Extension describes root rots that turn root tips dark brown and mushy, can blacken the lower stems, and make plants wilt even when the mix holds enough water.
If you suspect rot
Clemson says overwatering can lead to root rot. UF/IFAS adds that root rot may occur when ZZ plants grow in poorly drained or compacted mix with too much water for an extended period. It suggests taking a sample to a local extension office for diagnosis if problems persist.
Virginia Cooperative Extension’s fixes for overwatering are:
- Clear any blocked drainage holes.
- Let the mix dry out.
- Repot into new mix.
- Prune off dead or dying stems, leaves or roots.
University of Maryland Extension adds: use clean pots and sterile potting mix, keep the affected plant away from others, and take cuttings only from healthy tissue. If you need new plants, Illinois says division and leaf cuttings both work. Division is quicker.
Our root rot guide walks through the checks in more detail.
What speeds up or slows the dry-down
- Light. NC State says the ZZ grows in very low light but does best in bright, indirect light. Virginia Cooperative Extension says brighter light raises water use and dries the mix faster. A ZZ in a dim corner needs water less often.
- Season. NC State and Illinois both cut watering to once a month in the cooler months, when the plant is not actively growing.
- Temperature. Clemson says to keep the plant above 16 °C (60 °F). UF/IFAS says growth slows and injury may occur below 10 °C (50 °F). A cold plant uses little water, so wet mix lingers.
- Mix. Clemson suggests a coarse, well-draining mix of 50% peat- or coir-based potting soil, 25% perlite and 25% sand. NC State asks for well-drained potting soil; UF/IFAS says any well-drained peat- or bark-based mix can be used.
- Pot. Virginia notes terracotta dries faster than plastic or glazed pots. It also warns that a pot that is too large leaves roots in a zone that stays too wet.
Feeding and water quality
ZZ plants grow slowly and need little feed. Clemson says to fertilize only once or twice during the growing season with a balanced fertilizer. UF/IFAS rates its salt tolerance as slight. Do not add fertilizer to fix a struggling plant; check the roots first.
For tap water, chlorine and hard water, see our tap water guide. For a full care overview, see the ZZ plant care guide.
The short version
- Use a well-drained mix and a pot with drainage holes, not much bigger than the root ball.
- Check the mix every week or two. Water only when it has dried.
- Water until it drains, then empty the saucer.
- Expect roughly twice-monthly watering in a bright summer spot and monthly or less in winter, but let the check decide.
- If stems turn soft and the mix is wet, stop watering and check the roots.
References
- NC State Extension Gardener Plant Toolbox: Zamioculcas zamiifolia
- Clemson Cooperative Extension HGIC, J. Jordan: ZZ Plant (Zamioculcas zamiifolia): Indoor Care, Growing Tips & Plant Guide
- Iowa State University Extension and Outreach: I recently purchased a ZZ plant. How do I care for it?
- University of Illinois Extension, E. Swihart: Houseplant spotlight: the ZZ plant
- UF/IFAS Extension EP480, R. J. Henny and J. Chen: Florida Foliage House Plant Care: ZZ Plant
- Virginia Cooperative Extension SPES-804: Properly Watering Container Houseplants
- University of Maryland Extension: Root Rots of Indoor Plants