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If you read nothing else on this page, read this. Almost every ZZ plant that struggles in a New Zealand home struggles for one of two reasons, and both are easy to avoid.
Water it thoroughly, then leave it alone until the soil is dry all the way through. In an Auckland winter that can mean six weeks between waterings. Put it anywhere with usable light, including a dim corner, and keep it out of hot direct sun. That is genuinely the whole thing.
The two mistakes
Watering on a schedule. A ZZ plant stores its own water underground. When you top it up before it has used what it has, the rhizomes sit wet and begin to rot. This is the single most common cause of ZZ plant death, and it looks like kindness while you are doing it.
Assuming low light means no light. The plant survives in very low light, which is different from growing in it. In a genuinely dark corner it will hold its existing leaves for a long time and simply stop producing new ones. If you want new growth, give it a brighter spot.
What normal looks like
- New growth arrives as a tightly furled spear pushing up from the soil, not from an existing stalk. It unrolls over two to three weeks.
- New stalks are pale, almost lime green, and darken over a month or so. This is not a deficiency.
- One or two new stalks per growing season is normal. Some plants do more, most do not.
- Occasional loss of an old lower leaflet is ordinary ageing. Individual leaves live at least six months and often far longer.
- Growth largely stops between May and September. Nothing is wrong. It resumes as the days lengthen.
Where it comes from
Eastern Africa, in seasonally dry bushland and forest with rocky ground. It evolved for months of no rain followed by a short wet season, which is why it treats an occasional forgotten watering as normal weather.
Zamioculcas zamiifolia grows wild across a long stretch of eastern Africa, from Kenya and Tanzania south through Malawi, Mozambique and Zimbabwe to KwaZulu-Natal in north-eastern South Africa. It is not a rainforest plant, and that distinction explains almost everything about how it behaves indoors.
Its habitat is seasonally dry: open bushland, dry forest, and rocky partially shaded sites where the ground drains fast and rainfall arrives in a concentrated wet season rather than steadily through the year. In those places the plant spends a large part of the year with no available water at all. It survives on what it stored during the rains, sitting under a canopy in filtered light rather than open sun.
The practical translation for a New Zealand home is this. Your plant is not waiting for humidity, misting, or frequent watering. It is adapted to boom and bust, and a dry spell is the half of the cycle it is best at.
Go deeper: what the wild habitat tells you about pot choice
Wild plants root into rocky, gritty ground with large air spaces and rapid drainage. The soil never holds water against the rhizome for long, even after heavy rain. A dense peat-based potting mix in a plastic pot with one drainage hole is close to the opposite of that.
You do not need to replicate African bushland. You do need drainage that empties fast. A mix cut with pumice or bark, in a pot that is not oversized, gets you most of the way there. See potting mix.
Naming and history
Described in 1829, renamed twice, and then almost entirely ignored by the houseplant world until Dutch nurseries began mass-producing it in the mid 1990s. Nearly every ZZ plant sold today descends from that commercial push.
A genus of one
Zamioculcas is monotypic, meaning the genus contains a single species. Everything sold as a ZZ plant, including cultivars like Black Knight, Raven, Zenzi and Supernova, is a selection of Zamioculcas zamiifolia rather than a separate species. It sits in the Araceae, the arum family, alongside Monstera, Philodendron, Anthurium and peace lilies, in its own small subfamily with the rarely cultivated genus Gonatopus.
Three botanists, three names
The plant was first described in 1829 by the English nurseryman and illustrator George Loddiges, who published it as Caladium zamiifolium in his Botanical Cabinet. The Austrian botanist Heinrich Wilhelm Schott, who specialised in the arum family, later recognised it did not belong in Caladium and erected the genus Zamioculcas for it. The German taxonomist Adolf Engler settled the current combination, Zamioculcas zamiifolia, in 1905.
The name itself is a compound of two references. Zamio comes from Zamia, a genus of cycads that the plant's stiff pinnate leaves superficially resemble, despite no relationship whatsoever. Culcas comes from the same root as Colocasia, the taro genus, via the Arabic qolqas, and points to its actual family. The species name simply repeats the first half: zamiifolia, meaning Zamia-leaved.
How it reached your living room
For over 150 years after its description the plant remained a botanical curiosity rather than a commercial one. That changed around 1996, when Dutch nurseries developed reliable large-scale propagation from leaflet cuttings and began producing it in volume. It spread through Europe, then globally, and arrived in New Zealand retail as part of the same wave.
The timing mattered. The plant reached the market just as apartment living, office fitouts and low-light interiors were creating demand for something that would survive conditions most foliage plants will not. It is one of the few houseplants whose commercial success is directly attributable to a propagation breakthrough rather than a change in taste.
Go deeper: traditional use in its native range
The plant is not only ornamental in its home range. Among the Sukuma people of north-western Tanzania, the roots have been used as a topical application for ulceration. This is a documented ethnobotanical use rather than a recommendation, and given the plant's calcium oxalate content it should not be attempted at home.
How the plant works
Underground rhizomes store water. The leaves are around 91 percent water and hold it behind a thick waxy surface. At night, under drought stress, the plant can switch on a water-saving mode of photosynthesis normally seen in succulents and cacti. Understanding this is what makes the watering advice make sense.
The rhizomes
Under the soil, a ZZ plant grows from thick, potato-like rhizomes. These are swollen underground stems, not roots, and they function as water tanks. When conditions are good the plant fills them. When rain stops, it draws them down.
This is why a ZZ plant tolerates being forgotten and why it does not tolerate being overwatered. A full tank that keeps receiving water has nowhere to put it. The rhizome tissue stays saturated, oxygen cannot reach it, and rot organisms move in. The plant has no mechanism for refusing water you give it.
Leaves that are mostly water
The glossy leaflets are succulent in the true sense. Their water content has been measured at around 91 percent, with the leaf stalks higher again at roughly 95 percent. The heavy waxy cuticle that gives the plant its polished look is functional: it drastically slows evaporation. Individual leaves last at least six months, and in practice often years.
Together these traits produce the plant's most quoted party trick. Under low interior light levels, a ZZ plant can survive around four months with no water at all. Survive is the operative word. It is not growing during that time, it is spending reserves.
A part-time succulent metabolism
Most plants open their leaf pores during the day to take in carbon dioxide, and lose water while doing it. Cacti and many succulents instead open at night, when it is cooler and less water escapes, and store the carbon for use the next day. That night-shift pathway is called crassulacean acid metabolism, or CAM.
Zamioculcas does both. Research published in 2007 confirmed it runs a weak, facultative form of CAM: under well-watered conditions almost all of its carbon comes from ordinary daytime photosynthesis, with only about 0.2 percent taken up in the dark. Put it under drought stress and night-time uptake increases roughly sevenfold. It is a small contribution in absolute terms, but it helps the plant hold its position during a dry season rather than losing leaves.
Flowering
ZZ plants do flower indoors, and most owners miss it. The flower is a small spadix, a fleshy column of tiny flowers about 5 to 7 centimetres long, in yellow to bronze, and it appears at ground level partly hidden among the leaf bases rather than held up on a stem. In its native range flowering runs from mid summer into early autumn. Indoors in New Zealand it is most likely on a mature, well established plant between January and April.
It is not showy and it costs the plant energy. Many growers remove it at the base. There is no need to do so if you would rather watch it.
Go deeper: air purification, and what the research actually says
ZZ plants are widely marketed as air purifiers. The basis for this is a 2014 University of Copenhagen study which found that in a sealed laboratory chamber, the plant removed volatile organic compounds in the order benzene, toluene, ethylbenzene, then xylene.
The same study was explicit that the effect on real indoor environments is inconclusive. Chamber conditions are not living rooms, and the air exchange rate in an ordinary home dwarfs what a potted plant can process. Buy a ZZ plant because it is a good plant, not as air filtration.
Growing it
Bright indirect light for growth, low light for survival, no hot direct sun. Water thoroughly and then not again until dry throughout. Free-draining mix, snug pot, feed lightly October to April, repot every two to three years.
Light
A ZZ plant will live almost anywhere with usable daylight, including a hallway or a bathroom with a small window. Where you place it determines how fast it grows, not whether it lives.
For active growth, put it within a couple of metres of a window with bright indirect light. In New Zealand, north-facing windows give the strongest light through the day, east-facing gives gentler morning sun, and south-facing gives the least. A spot beside a north or east window, slightly back from the glass or behind a sheer curtain, is close to ideal.
What it will not take is hours of direct summer sun through unshaded glass. The leaves are dark, waxy and hold heat, and New Zealand's high UV levels will bleach and scorch them.
Too little: no new stalks for a full growing season, and new stalks that emerge long and sparse with wide gaps between leaflets, leaning towards the window. Too much: pale washed-out patches, or dry brown scorch marks, on the side facing the glass.
Water
This is the section that decides whether your plant thrives. The method matters more than the frequency.
- Check first, always. Push a finger, a wooden skewer or a chopstick to the bottom of the pot. If it comes out with any damp soil clinging to it, do not water. The surface tells you nothing.
- Water thoroughly when it is dry throughout. Take it to a sink and water until it runs freely from the drainage holes. Half-measures leave dry pockets and encourage shallow roots.
- Let it drain completely. Give it several minutes, then tip out anything that has collected in the cover pot or saucer. A ZZ plant standing in water is the beginning of rot.
- Wait. Then repeat the check. Do not water again on a schedule.
In practice, in an Auckland home, expect roughly every three to four weeks between October and April, and every five to eight weeks between May and September. Those numbers are a starting expectation, not an instruction. A small pot in a warm bright room dries far faster than a large pot in a cool dim one.
A ZZ plant that is a week too dry loses nothing. A ZZ plant that is a week too wet may be losing rhizome tissue you cannot see.
Water quality
New Zealand tap water is fine for ZZ plants across almost all of the country. Auckland's supply is soft and low in minerals, and the plant is not sensitive in the way a Calathea is. If your water is heavily chlorinated, standing it in an open jug overnight is enough. Rainwater is a small bonus, not a requirement.
Temperature
Comfortable between 18 and 28 degrees, which covers most New Zealand indoor conditions year round. It will hold steady down to about 12 degrees but stops growing well below 15.
Cold is more of a risk than heat in a typical New Zealand house, where winter indoor temperatures often sit lower than people assume. Keep it away from single-glazed windows on frosty nights, away from draughty doorways, and away from the direct blast of a heat pump, which dries and stresses foliage from one side.
Humidity
Genuinely not a concern. This is a dry-season plant with waterproofed leaves. Ordinary New Zealand indoor humidity, typically 40 to 60 percent, suits it completely.
Do not mist it. Misting does nothing useful for a plant with this leaf structure, and water pooling in the tight joints where leaflets meet the stalk is a small invitation to fungal spotting.
Potting mix
The goal is a mix that wets thoroughly then drains and dries. A standard bagged indoor potting mix on its own holds too much water for too long.
A reliable blend is roughly two parts quality indoor potting mix, one part pumice or perlite, and one part orchid bark or coarse coir chips. Pumice is easy to find in New Zealand, is locally sourced, and is heavier than perlite, which helps stabilise a tall plant. If you would rather buy something ready-made, a cactus and succulent mix cut with a third indoor mix works well.
Feeding
Light and infrequent. Feed only during the growing season, October to April, and only when the plant is actively pushing new stalks.
A balanced liquid indoor plant fertiliser at half the recommended strength, once every six to eight weeks, is plenty. Feed onto damp soil rather than dry, so nothing burns the roots. Stop entirely from May. A slow-release granular feed applied once in spring is a good alternative if you would rather not think about it.
A ZZ plant that is not growing is nearly always short of light or in the wrong season. Feeding it more will not start growth, and unused fertiliser salts build up in the mix and damage roots.
Repotting
Every two to three years, or when rhizomes are visibly pressing against the sides of the pot or lifting the surface of the soil. ZZ plants are content slightly snug, and a pot that is too large holds a reservoir of wet soil that the plant cannot use.
Go up one pot size only, around 3 to 5 centimetres in diameter. Repot in spring or early summer, when the plant can put out new growth into the fresh mix. Terracotta is a genuinely good choice here, since it wicks moisture out of the mix and forgives generous watering.
Size and growth expectations
Indoor plants generally settle between 45 and 90 centimetres tall, with mature specimens in good light reaching around a metre. Growth is by whole new stalks emerging from the rhizome rather than extension of existing ones, which is why the plant appears to do nothing for months and then produce a complete new frond.
One to three new stalks per growing season is a healthy rate for an established plant. Dark-leaved cultivars including Black Knight and Raven are slower again.
Go deeper: cleaning, staking and shaping
Cleaning. The gloss is the point of this plant, and dust reduces both the look and the light reaching the leaf. Wipe leaflets with a soft damp cloth every couple of months, supporting each stalk from behind with your other hand. Avoid commercial leaf shine products, which clog the leaf surface.
Splaying stalks. Older plants often open outward from the centre. This is usually a light issue: stalks lean towards the brightest side and gradually pull the plant apart. Rotate the pot a quarter turn every time you water. A discreet ring stake will hold an established plant together, though correcting the light is the real fix.
Pruning. Remove a yellowed or damaged stalk by cutting it right at soil level with clean secateurs. Do not shorten a stalk part way, since it will not branch and the cut end simply dies back. Removing whole stalks does not stimulate new growth, so prune for appearance only.
Propagation
Three methods, in order of speed. Dividing the rhizomes gives you a finished plant immediately. A stem cutting takes a few months. A single leaflet takes the better part of a year, and is the most quietly satisfying thing this plant does.
All three work because of the same underlying ability: ZZ plant tissue can form a new rhizome from almost nothing. A detached leaflet, given warmth and time, will grow a small tuber of its own before it grows a single root or leaf.
Method 1: Division
Fastest and most reliable. Best done in spring or early summer at repotting.
- Do not water for a week or two beforehand. Slightly dry mix falls away more cleanly and reduces rot risk at the cut surfaces.
- Slide the plant out and gently work the soil off the rhizome cluster so you can see what you are doing.
- Find a natural separation point where a rhizome has both its own roots and its own stalks. Ease it apart by hand where possible, and use a clean sharp blade only where you must.
- Leave the divisions in open air in the shade for a few hours so the cut surfaces dry and seal.
- Pot each division into free-draining mix in a pot only slightly larger than the rhizome. Water lightly once, then treat as normal.
Method 2: Stem cuttings
A whole stalk, or a section of one, will root and form a rhizome. This is the middle option: slower than division, but each new plant starts with a full frond already attached.
- Cut a healthy stalk at its base with clean secateurs. You can use it whole, which looks better, or cut it into sections at least 15 centimetres long.
- Strip the leaflets from the bottom few centimetres, then let the cut end callus in the shade for a few hours.
- Either stand it in a narrow vase with just the cut end covered, changing the water twice a week, or push it a few centimetres into moist free-draining mix.
- Keep it warm and in bright indirect light. Expect the first roots at around three weeks in water, with a small rhizome forming behind them over the following two to three months.
- Pot up once roots are several centimetres long and you can feel a firm swelling at the base.
Water lets you watch progress and is more fun, but water-formed roots adapt poorly to soil and the risk of rot is higher over long periods. Soil is slower to show results and more reliable. For a single treasured cutting, use soil.
Method 3: Leaflet cuttings
The method Dutch nurseries built the commercial ZZ industry on, and the one that requires real patience at home. A single detached leaflet will produce a rhizome of its own.
- Pull or snip individual leaflets from a healthy stalk, taking the small stub where the leaflet joins the stalk if you can. Whole leaflets outperform halved ones.
- Let them callus in the shade for a few hours.
- Push each leaflet upright about one centimetre into moist, free-draining mix, cut end down. A shallow tray of several dozen is the traditional approach.
- Keep the mix barely moist, never wet, in bright indirect light and as warm as you can manage.
- Wait. Then wait more. Do not disturb them, and do not throw them out because nothing is happening above the soil.
Commercial trials give a useful picture of the timeline. Under nursery conditions with a 16 hour photoperiod, leaflet cuttings reached 90 to 100 percent success at forming roots and a rhizome, with apical leaflets from the tip of the stalk averaging 4.3 rhizomes per cutting after six weeks against 1.4 for leaflets taken from the base. Grown on at 29 to 32 degrees, those cuttings became saleable plants in six to eight months. Below 26 degrees, leaf development was measurably delayed.
A New Zealand windowsill is not a Dutch glasshouse. At typical indoor temperatures, expect a rhizome in roughly three to nine months and a first true stalk somewhere between nine months and a year and a half. Start them in October so the warm months do the work.
Go deeper: why success rates are so high, and rooting hormone
Research comparing leaflets taken from the apical, middle and basal positions on a stalk found all three positions equally capable of rooting and forming rhizomes, at 90 to 100 percent success. What differed was quality rather than survival: whole leaflets produced more roots, better root scores, larger rhizomes and a bigger first shoot than half-leaflet segments. The initial size and weight of the cutting correlated directly with the size of rhizome it produced.
The practical conclusion is to use whole, large, healthy leaflets and take as many as you like from anywhere on the stalk. Cutting leaflets in half to get more propagules works, but each resulting plant starts smaller and slower.
Rooting hormone is not necessary. Trials using IBA dips have shown improved callus and root development, so it will not hurt, but a plain leaflet in warm moist mix succeeds at very high rates on its own.
Diagnose a problem
Tick everything you can actually see on your plant. The more you tick, the better this gets at separating causes that look alike.
Water problems
Overwatering and underwatering both cause yellowing, which is why they get confused. The difference is texture. Overwatered tissue goes soft, dark and mushy. Underwatered tissue goes thin, wrinkled and papery.
Rhizome and root rot
The serious one, and the most common cause of ZZ plant death. It is a fungal or bacterial infection of waterlogged tissue, usually the result of soil staying wet longer than the plant can use it. Contributing causes are a pot with no drainage, a cover pot holding standing water, a mix that is too dense, a pot too large for the plant, or watering to a calendar rather than a check.
How to identify it
- Yellowing that appears on several stalks at once, rather than working up one stalk from the bottom.
- Stalk bases that feel soft when gently squeezed, or that have gone dark and translucent near the soil.
- Stalks that pull free from the soil with almost no resistance.
- Soil still visibly damp more than two weeks after watering.
- A sour, swampy or sulphurous smell from the soil surface.
- Rhizomes that are soft, brown or grey rather than firm and pale. This is the definitive test.
Take the plant out of its pot and look. There is no way to diagnose rot from above the soil, and every day you spend guessing is a day the rot spreads. A healthy rhizome is firm and pale, like a raw potato. A rotting one gives under thumb pressure.
How to treat it at home
- Remove the plant and wash all the old mix off the rhizomes under a gentle tap so you can see every surface.
- With a clean sharp blade, cut away every soft, dark or smelling section until you are cutting into firm pale tissue. Wipe the blade between cuts.
- Remove any stalk attached to a rhizome you have had to cut out entirely. It has no support left.
- Leave the remaining healthy rhizomes in open air in the shade for a few hours to a full day so the cut surfaces dry and seal.
- Repot into fresh free-draining mix in a pot sized to what is left, which will often be smaller than the original. Do not reuse the old mix.
- Do not water for at least a week. Then water sparingly until you see new growth.
Recovery is realistic if you have caught it with firm rhizome remaining. If every rhizome is soft, the plant cannot be saved, but healthy leaflets taken from unaffected stalks can still be propagated. That is worth doing before you give up on it.
Underwatering and severe drought
Far less dangerous, and usually reversible. The plant draws down its rhizomes first, then begins sacrificing leaves.
How to identify it
- Leaflets that have lost their plumpness, feeling thin and papery rather than firm.
- Wrinkling or slight inward curling along the leaflet, and a loss of gloss.
- Whole stalks drooping or leaning outward while remaining firm at the base.
- Soil pulled away from the sides of the pot, and a pot that feels noticeably light.
- Yellowing that starts on the oldest lower leaflets and works upward.
How to treat it
If the mix has gone hydrophobic and water runs straight through, stand the pot in a basin of room-temperature water for 20 to 30 minutes so it rehydrates from below, then drain fully. Otherwise water thoroughly at the sink. Do not fertilise a drought-stressed plant, and do not water again until it is dry throughout. Leaflets will firm up within a few days. Stalks that have fully yellowed will not recover and can be removed at the base.
Light problems
Too much sun bleaches and burns on the window side only. Too little light does not damage anything, it just stops the plant growing and makes new stalks stretch and lean.
Sun scorch
Caused by direct sun through unshaded glass, most often between November and February, and most often after a plant has been moved from a dim spot to a bright one without transition.
How to identify it
- Damage on the side of the plant facing the window, with the shaded side untouched. This asymmetry is the giveaway.
- Pale, washed-out or yellowish patches on the upper leaflet surfaces, which may later dry to crisp tan or brown centres.
- Sharply defined edges to the damaged areas rather than a gradual fade.
- Onset over days after a move or a run of hot clear weather, not gradual over months.
How to treat it
Move it back from the glass, or add a sheer curtain. Scorched tissue does not repair, so remove badly marked stalks at the base once the plant has stable growth elsewhere. When you next move a plant into brighter conditions, do it over two weeks in stages rather than all at once.
Insufficient light
Not damage, and not urgent. It is a growth ceiling.
How to identify it
- No new stalks across an entire October to April growing season.
- New stalks that emerge unusually long and thin, with wide spacing between leaflets and fewer of them.
- The whole plant leaning towards the light source.
- Existing leaves looking perfectly healthy, which is what makes people miss it.
How to treat it
Move it closer to a north or east-facing window, or add a simple LED grow light on a timer for eight to ten hours a day. Rotate the pot a quarter turn at every watering. Stretched stalks will not shorten, so cut the worst offenders at soil level once new, better-proportioned growth has established.
Pests
ZZ plants are unusually pest resistant. The waxy leaf surface deters most insects, and healthy plants are rarely troubled. When pests do appear it is usually spider mites in a dry warm room, or mealybugs brought in on a new plant.
ZZ leaves are heavily waxed and water beads straight off them. Any spray you use needs a wetting agent, or it will roll off before it makes contact. In New Zealand, Grosafe Enspray 99 works both as a treatment and as a wetting agent for exactly this reason.
| Pest | What you see | Where to look | Confirm it |
|---|---|---|---|
| Spider mites | Fine pale stippling or speckling across the leaf surface, loss of gloss, and eventually fine webbing | Undersides of leaflets and the tight joints where leaflets meet the stalk | Hold a sheet of white paper under a stalk and tap it. Moving specks the size of dust confirm mites |
| Mealybugs | White cottony blobs, and a sticky residue on lower leaves or the surface below the plant | Leaf joints, the base of stalks, and just below the soil line on the rhizome | Touch one with a cotton bud dipped in isopropyl alcohol. Mealybugs go translucent brown |
| Scale | Small firm brown or tan bumps that look like part of the plant, plus sticky residue | Along the stalk itself, and on the underside of the leaflet midrib | Scrape one with a fingernail. Scale lifts off and leaves a mark. A natural blemish will not |
| Fungus gnats | Small black flies drifting around the pot and the room, worst just after watering | The top few centimetres of soil | Press a slice of raw potato onto the soil for two days, then lift it and look for larvae underneath |
Treating spider mites
Mites thrive in warm, dry, still air and reproduce fast, with a life cycle as short as five days in summer. Speed matters.
- Isolate the plant immediately, away from every other plant in the house.
- Take it to a shower or outside and rinse thoroughly, paying attention to leaflet undersides and joints. This alone removes most of the population.
- Treat with a registered miticide. In New Zealand, Yates Mavrik or Grosafe Enspray 99 are both effective and available at Mitre 10, Bunnings and garden centres. If using Mavrik on this plant, add Enspray 99 as a wetting agent so it holds on the waxy leaf.
- Repeat every five to seven days for at least three treatments. Eggs are not killed by contact sprays, so a single application always fails.
- Wipe the leaves clean between treatments and check the plant weekly for a month afterwards.
Treating mealybugs and scale
Both are protected by a waxy or armoured coating, which is why generic sprays underperform against them.
- Isolate the plant.
- Remove every visible insect individually with a cotton bud dipped in isopropyl alcohol. This is tedious and it is the part that actually works.
- Follow with a horticultural oil across the whole plant. Grosafe Enspray 99 or Yates Conqueror Oil both suit, and they work by smothering rather than poisoning, so full coverage is essential.
- Check the soil line and just below it. Mealybugs frequently colonise the rhizome where nobody looks, and a plant that keeps reinfesting almost always has them there.
- Repeat every seven to ten days for three to four rounds.
Treating fungus gnats
Fungus gnats are a symptom rather than a disease. They breed in soil that stays damp, so on a correctly watered ZZ plant they should not have anywhere to live.
- Let the soil dry out completely and thoroughly. On this plant that is safe, and it breaks the breeding cycle by itself.
- Cover the soil surface with a one centimetre layer of pumice or coarse grit so adults cannot reach the soil to lay.
- Yellow sticky traps catch the flying adults and let you monitor whether numbers are dropping.
- If they persist, treat the soil with a product containing Bacillus thuringiensis israelensis, which targets the larvae and is harmless to the plant.
- Then look at why the soil was staying damp. That is the actual problem, and it is the same one that causes rot.
Other issues
| What you see | Most likely cause | What to do |
|---|---|---|
| One lower leaflet yellows and drops occasionally | Normal ageing. Individual leaves live months to years, then are shed | Nothing. Remove it if you prefer the look |
| Brown crispy tips and edges only, rest of the leaflet fine | Fertiliser salt buildup, or prolonged dryness combined with heat pump air | Flush the pot with plenty of water at the sink, stop feeding for two months, and move it away from direct heat pump flow |
| Leaflets drop off intact and green, without yellowing first | Cold shock, or a sudden environmental change such as arriving from a shop | Move to a stable spot between 18 and 28 degrees, away from draughts and cold glass, and leave it alone for a month |
| Stalks splaying outward, plant opening at the centre | Uneven light, and normal weight distribution as stalks mature | Rotate a quarter turn at every watering, improve overall light, and use a discreet ring stake if needed |
| Whole plant looks dull, has lost its shine | Dust, or early spider mite damage | Wipe with a soft damp cloth. If the dullness persists after cleaning, check for mites |
| Rhizomes pushing above the soil or deforming the pot | Root bound, and due for repotting | Repot in spring, one size up only, into free-draining mix |
| New growth is pale lime green | Nothing. This is what new ZZ growth looks like | Wait. It darkens over three to four weeks |
| Nothing at all has happened for months, in winter | Seasonal dormancy | Reduce watering, stop feeding, and wait for October |
| Black or brown mushy patches spreading up a stalk from the soil | Rot advancing upward from the rhizome | Act now. See rhizome and root rot |
Safety and pets
Mildly toxic, not dangerous. All parts contain sharp microscopic crystals that cause immediate mouth pain and irritation if chewed. Unpleasant rather than serious, and the pain itself usually stops animals after one bite.
Like most of the arum family, Zamioculcas contains insoluble calcium oxalate in the form of raphides: needle-shaped crystals held under pressure in the plant tissue. When an animal or child bites into a leaf or stalk, the crystals are released into the soft tissue of the mouth. The effect is mechanical rather than chemical, which is why it hurts instantly rather than hours later.
Symptoms in cats and dogs
- Pawing at the mouth or rubbing the face along the floor, often the first sign in cats.
- Sudden heavy drooling.
- Head shaking, and reluctance to eat.
- Vomiting or diarrhoea if a quantity has been swallowed.
What to do
Remove any remaining plant material from the mouth and offer water, milk or a small amount of food to help flush the crystals through. Symptoms usually settle within a few hours. Contact your vet if drooling persists beyond that, if there is any swelling around the mouth or throat, or if breathing seems affected, which is rare but possible.
For people
The same applies. The sap can irritate skin and eyes, so wash your hands after pruning, repotting or taking cuttings, and avoid touching your face while you work. Wear gloves if you have sensitive skin.
The ZZ plant is often described as extremely poisonous. It is not, and it does not appear on the ASPCA toxic plant list at all. Separately, a rumour that circulated from around 2010 claiming ZZ plants cause cancer is entirely false and has no scientific basis.
The sensible position is the same one you would take with a Monstera or a peace lily. Keep it out of reach of animals that chew plants and of small children, and enjoy it.
Questions
Why has my ZZ plant not grown in six months?
If those six months were between May and September, nothing is wrong. Growth stops over a New Zealand winter and resumes as days lengthen. If it covers a full October to April season with nothing, the answer is almost always light. Move it closer to a north or east-facing window and expect a response the following spring rather than immediately.
Can a ZZ plant really live in a room with no window?
It can survive surprisingly long in very low light, drawing on stored reserves, but it cannot grow there indefinitely. A windowless room with lights on during working hours, such as an office, is workable. A genuinely dark room is not a long-term home. If you want to use one, consider rotating two plants between the dark spot and a bright one every few weeks.
How do I tell overwatering from underwatering when both look yellow?
Feel the base of the stalks. Overwatered plants go soft, dark and mushy at soil level, and the soil is still damp. Underwatered plants stay firm at the base while the leaflets go thin and wrinkled, and the pot feels light. If you are still unsure, take it out of the pot and look at the rhizomes. Firm and pale means dry. Soft and brown means rot.
Is the black ZZ plant cared for the same way?
Yes, with one adjustment. Dark cultivars such as Black Knight and Raven emerge bright lime green and darken to near black as they mature, and the dark pigment develops best in good light. In a dim corner they will stay greener. They also grow more slowly than the standard green form, so give them more time before concluding anything is wrong.
My ZZ plant fell over and snapped a stalk. Is it wasted?
No. A snapped stalk is a free propagation opportunity. Trim the broken end cleanly, let it callus for a few hours, and either root the whole stalk or strip it into individual leaflets. See the propagation section above.
Should I mist my ZZ plant or use a humidifier?
Neither. This is a dry-season plant with waterproofed leaves, and ordinary New Zealand indoor humidity suits it completely. Misting achieves nothing and can encourage fungal spotting where water pools in the leaf joints.
How long will a ZZ plant live?
Decades, with reasonable care. ZZ plants are long-lived, slow-growing and essentially free of the accumulated problems that shorten the life of faster plants. A well-kept specimen will outlast most of the furniture in the room.
