Why does my Swiss cheese plant have brown crisp edges on the leaves?

On a Swiss cheese plant the edge of a leaf goes tan to brown and brittle, in a thin even band that follows the outline, including the edges of the splits. The middle of the leaf stays green, and the plant otherwise looks healthy.

The most likely cause for this plant is dry air or a dry spell. It is comfortable in ordinary room humidity, but the Royal Horticultural Society notes that central heating browns the leaf edges, and a pot left to dry right through between waterings does the same. Watered every 7 days or so in the growing season and every 12 in winter, it should never get that far.

To confirm it in a minute, push a finger into the mix to the second knuckle. If it is bone dry and the pot is light, the plant has been left too long. If the mix is moist, look at where the plant stands. Browning that began when the heating came on, on the leaves nearest a radiator, a heater or an air conditioner, points to the air.

The third cause is salt. Look at the surface of the mix and around the drainage holes for a white or pale crust. It builds up in a plant fed above the strength on the bottle, or watered with a little at a time so that nothing flushes through, and the RHS advises rainwater or filtered water for this plant, especially where the tap water is hard.

The brown parts never turn green again, and the plant cannot repair them, so judge the recovery by the new leaves. Once the cause is dealt with, the next few leaves should open with clean edges. In the growing season that takes a few weeks. In winter the plant makes hardly any new growth, and it will be spring before you can say.

What this plant wants

The fix

Water more evenly and move it away from heaters and air conditioning. Group it with other plants.

Read on

Brown crisp edges on the leaves

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.