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

On a ZZ plant this is a dry, tan to brown patch or edge on the leaflets, with the gloss gone from the area around it. The leaflets facing the window are marked first and worst, and the leaflets on the shaded side or the middle of the clump are still glossy and green.

The most likely cause is direct sun through glass. The entry says it bleaches the gloss off the leaflets and leaves dry brown patches that never green up again, and the NC State plant toolbox says scalding and browning of the leaves can occur when the plant is placed in direct sunlight.

To confirm it in a minute, stand where the plant stands at midday on a clear day and see whether a beam of sun reaches it. Look at which leaflets are marked. If they are only the ones facing the glass, it is sun. The second cause on the entry's list is a hot, dry spot, so check whether it sits beside a radiator or a heater.

The other thing to rule out is salt. The page on brown crisp edges names a pale crust on the surface of the compost or around the drainage hole, left by feeding, and the entry feeds only two or three times a year at half strength. Dry air is less likely, because the Royal Horticultural Society says average household humidity is enough for this plant.

Damaged leaflets never recover, so you judge the recovery by new stems, which unfurl bright green and glossy once the plant is out of the sun. This plant grows slowly, perhaps five new stems a year in bright indirect light by the entry's account, and almost none in winter.

What this plant wants

The fix

Move it out of the sun beam and away from the heat. Damaged leaflets do not recover, so cut the worst stems out at the base.

Read on

Brown crisp edges on the leaves

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

ZZ 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.