Why does my Swiss cheese plant have new leaves with no splits?

On a Swiss cheese plant the new leaves open solid and heart shaped, with no splits along the edges and no holes between the veins, or they come smaller and plainer than the leaf before. Older leaves lower down may be larger and more cut, which shows what the plant can do.

The most likely cause is age. The Royal Horticultural Society says the distinctive holes usually appear only once the plant is a few years old, and every Monstera begins with plain leaves. If yours is small, under about half a metre, and growing steadily, nothing is wrong. Compare several leaves in a row: if each is a little more divided than the last, the plant is on its way.

On a mature plant, light is next. A split leaf costs the plant more to make, and a plant short of light makes the cheaper, solid kind instead. The RHS notes that in very low light the leaves tend to have fewer holes. To confirm it, look at where the plant stands at midday. If it is more than a metre or two from a bright east or west window, or a tree outside has come into leaf and shaded the room, light is the cause.

The third thing to rule out is support. This is a climber, and the RHS says a plant trained on a moss pole tends to make mature leaves with more holes. One that sprawls sideways, with its aerial roots hanging in the air, keeps its leaves small. Hard pruning has a similar effect for a while, because new stems start again with fewer holes until the plant settles down.

Expect the change to be slow. After a move to brighter light, or onto a pole, the next leaves should be larger and more divided, but each one takes weeks to unfurl in the growing season and the plant hardly makes any in winter. Judge it by the leaves made between spring and autumn.

What this plant wants

The fix

Move it closer to a bright window. Leaves split as the plant matures and the light improves.

Read on

Monstera not splitting: why new leaves have no holes

The same sign on any plant, with the causes in the order they are likely.

Swiss cheese plant care

Light, water, feeding, repotting and the rest of the entry.

Check it in the diagnoser

Opens with the plant, the part and the sign already chosen.