Monstera: Why Leaves Don't Split and How to Care for It

Published 2026-10-30 · 8 min read

A Monstera deliciosa grows split leaves once it is old enough and gets bright indirect light. If yours keeps sending out whole, heart-shaped leaves, it is either still juvenile or sitting in light below roughly 250 lux at the leaf. Both are fixable, and the second cause is the one that happens indoors.

The plant sold as Swiss cheese plant is an aroid from southern Mexico and Central America. It climbs trees in the wild with thick aerial roots and leaves up to a metre long. In a British living room it grows fast, forgiving of missed waterings, and gives you the split leaves — fenestrations — most people bought it for, as long as you give it something to climb and a window worth sitting near.

What is a Monstera?

Monstera deliciosa is an evergreen climber in the family Araceae, the arums. Its leaf is glossy, leathery, and neither a true leaf nor a divided one: the plant makes holes and deep cuts as the leaf expands, the same way a tear can open in stretched fabric. The holes let light reach the leaves below it on the same vine.

Two species carry the name in most plant shops. Monstera deliciosa has leaves 30–60 cm across indoors, with both oval holes and deep cuts that reach the midrib. Monstera adansonii, the Swiss cheese vine, has leaves 10–25 cm long, mainly oval holes, and a trailing habit that suits a shelf. Both climb, both need the same treatment, and neither splits while small.

The split-leaf philodendron is not a monstera. The plant sold under that name is Thaumatophyllum bipinnatifidum, a different genus with a trunk and leaves cut all the way to the base. It is a fine houseplant; it just answers to a name that sends people looking for care advice that does not fit.

Why won't my Monstera leaves split?

Fenestration is a size signal. A cutting, or a plant that has been cut back hard, starts again with small whole leaves, and the splits return when the plant has enough leaf area to support them. That usually means several leaves after the first year, not the first weeks after you bring it home.

Light is the lever you control. A monstera that gets 8 or 9 hours of an ordinary desk lamp still sits in light that reads as dusk to the plant, because a domestic bulb delivers a few hundred lux at best at leaf height. Growth slows, internodes stretch, and the new leaves come out smaller and solid. The plant is not being stubborn; it is making the leaves its budget allows.

There is a third possibility worth ruling out: a plant with no support. A monstera that cannot climb grows along the pot rim, and the leaves stay small. Give it a moss pole and the next few leaves change shape.

How much light does a Monstera need?

Bright indirect light, with a number attached. For most of the day aim for roughly 500–2,000 lux at the leaf, which is a windowsill out of direct sun or a spot a metre back from a south-facing window. Direct summer sun through glass can exceed 20,000 lux and will scorch leaves that were not acclimatised, so the first week in a sunnier spot needs a sheer curtain.

The bands that matter in practice: below about 100 lux, the plant holds on but stops producing leaves; 100–250 lux keeps it alive and growing slowly, with small whole leaves; above 250 lux, and especially above 500, new leaves come out larger and cut. If you have a north-facing room, the plant can still work, but it needs to be within about a metre of the glass.

Measure the spot rather than guess it. Hold a phone running a free lux meter at leaf height, screen flat, and take a reading at 10:00, 13:00 and 17:00 on a normal day. Absolute numbers differ between phones by a wide margin; the pattern is what tells you whether the plant gets a bright morning, a hot afternoon, or neither.

How often should you water a Monstera?

Every 7–14 days while it is growing, which is roughly every 10–14 days in winter. The interval is not the point; the state of the compost is. Push a finger 3–5 cm into the mix. If it is still cool and damp there, wait.

Lift the pot instead of poking at it once you know the weight of it dry. A pot that feels light comes off the shelf; a pot that feels heavy goes back. Then water slowly until it runs out of the drainage hole, and empty the saucer ten minutes later. A monstera left standing in water loses roots, and the signs — yellow lower leaves, then a soft black stem at soil level — arrive a fortnight later.

What soil, pot and support does it need?

A chunky, airy mix holds up better than compost alone: roughly a third potting compost, a third bark or coco chips, a third perlite. Water runs through it rather than sitting in it, and the roots get the air they need.

Pot it 2–4 cm wider than the root ball, no more. A monstera in an oversized pot sits in wet soil it cannot drink fast enough, and repotting too generously is a common cause of root rot. Repot about every two years in spring, when roots show at the drainage holes or circle the surface.

The support is part of the care, not decoration. Tie the main stem to a moss pole or coir totem and keep the pole slightly damp, since the aerial roots that grip it take up water. Direct stray aerial roots into the pole or back into the pot. Cutting them all off does not kill the plant, but it does slow it down.

Temperature matters less than people expect: anything from 15 °C to 30 °C suits it. It dislikes cold draughts and a windowsill that drops to single figures in January more than it dislikes a warm corner.

Why is my Monstera making smaller leaves?

Small leaves with long gaps between them are a report on conditions, not a disease. Work through these in order:

Move the plant so a mid-morning reading at leaf height clears 500 lux.
Give the stem something to climb and tie it in at two points.
Check the pot: roots circling the surface mean repot into a pot 2–4 cm wider, in spring.
Feed from spring to early autumn, and flush the pot with plain water every few months.
Expect the change over three to four leaves, not overnight.

When and how should you fertilise?

A balanced liquid houseplant feed at half the label strength, every 30–60 days from spring to early autumn. Stop in winter, when growth slows and unused salts stay in the compost. Do not feed a dry plant — water first — and leave a freshly repotted plant alone for about four weeks, since fresh compost already carries nutrients.

What is wrong with my Monstera?

What you see	Likely cause	What to do
New leaves whole and small, long gaps	Too little light	Move closer to the window, add a grow light
Yellow lower leaves, compost still wet	Too much water	Let it dry out, check the drainage hole
Yellow leaves with dry, crumbly edges	Too little water, or salts	Soak the pot, then flush it through
Brown crisp tips and margins	Dry air or fertiliser salts	Raise humidity, flush the compost
Black soft stem at soil level	Root rot	Cut above the rot and re-root the tip
Leaves with holes, none with deep cuts	Young plant, or light too low	Time, and more light
White crust on the compost surface	Salts from hard water	Scrape it off, water with filtered water

Is a Monstera toxic to cats and dogs?

Yes. The ASPCA lists Monstera deliciosa as toxic to both dogs and cats, under the common name cutleaf philodendron, alongside hurricane plant, Swiss cheese plant, ceriman, Mexican breadfruit, split-leaf philodendron and window leaf plant. The toxic principle is insoluble calcium oxalate crystals.

Those crystals are shaped like needles, and chewing a leaf or a stem drives them into the tissue of the mouth. The ASPCA lists the clinical signs as oral irritation, intense burning and irritation of the mouth, tongue and lips, excessive drooling, vomiting and difficulty swallowing. A cat that nibbles a dropped leaf usually shows the reaction within minutes, and the drooling is often the first thing you notice.

The practical answer is placement, not removal. A monstera on a shelf, a tall stand or a hanging basket is out of reach; a monstera on the floor next to the cat's bed is not. Keep fallen leaves off the floor, and wash your hands after handling a stem you have just cut, since the sap irritates skin too.

When to call the vet

Heavy drooling after your pet chewed a leaf or a stem.
Pawing at the mouth, or rubbing the face along the floor or furniture.
Redness or swelling of the lips, tongue or gums.
Vomiting, especially more than once, or a pet that refuses food afterwards.
Trouble swallowing, or noisy, laboured breathing.
Any of these signs in an animal that chewed a plant you cannot identify.

In the UK, call your vet. If you are in the United States, the ASPCA Poison Control line is (888) 426-4435 and runs 24 hours a day.