Why does my Swiss cheese plant have yellow lower leaves?

On a Swiss cheese plant this shows as a leaf near the base of the stem turning a clear yellow, often between the veins or at the edge first, then across the whole blade, while the leaves higher up stay deep, glossy green. The leaf goes soft before it goes papery, and it can hang on the stem for a week or two before it lets go.

The most likely cause is the pot rather than the leaf. This is a forest climber whose roots want air as much as water, and the mix it is meant to live in is chunky bark, perlite and coir that drains fast. Watered about every 7 days in the growing season and every 12 or so in winter, it is content. Keep to the weekly rhythm through a dark winter, when the plant is using far less, and the mix stays wet, the fine roots suffocate, and the oldest leaves are the first to be given up.

To confirm it in a minute, push a finger into the mix to the second knuckle, about 5 cm down. If it is damp, that is your answer. Then lift the pot. One that is still heavy several days after watering, or that sits in a saucer of water, holds more than the roots can use.

Two other causes are worth ruling out. A single bottom leaf yellowing while everything above it is firm, with a new leaf unrolling at the top, is just the plant retiring an old leaf. Yellowing that creeps upwards over weeks on a plant standing well back from the window, with new leaves smaller than the old ones, is a light problem.

A yellow leaf will not turn green again, so judge the recovery by the next new leaf, which should come through healthy once the mix has dried out properly. In the growing season expect to see that within a few weeks. In winter the plant is resting, and it may be spring before you can tell.

What this plant wants

The fix

Let the mix dry further between waterings and check the pot drains. Remove fully yellow leaves.

Read on

Yellow leaves at the bottom of the plant

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.