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

On a rubber plant the edges of the big leaves turn brown and brittle in a band that follows the outline, while the middle of the leaf stays dark green and glossy.

The most likely cause for this plant is dry air or salt from feeding. The entry lists dry air, underwatering and salts, and its body says brown crisp edges point to dry air or feed salts. The thick leaves store water, so a rubber plant is slow to suffer from a missed week at its 9 day growing season or 18 day winter rhythm, which makes thirst the less likely of the three. Salt builds up when feed is applied above the strength on the bottle, or is not flushed out, especially in winter when the plant is not growing.

To confirm it in a minute, look at the surface of the compost and around the drainage holes for a white or pale crust, which is the salt. Then ask when the browning began. Edges that browned after the heating came on, on the side nearest a radiator, are the air. A finger pushed 3 to 4 cm into the compost tells you whether the compost has been left dry too long.

Two other causes are worth ruling out. Direct sun through glass scorches the leaves facing the window, and only those. The Royal Horticultural Society says that dry, shrivelled leaves on ornamental figs can come from insufficient humidity, dry compost or too much direct sun. Feeding above the strength on the bottle, or right through winter, is the usual way salt builds up.

Brown edges never turn green again, so judge the recovery by the new leaves, which should open with clean margins once the cause is dealt with. A new leaf takes weeks in the growing season. In winter the plant makes almost no new growth, so you may not know until spring.

What this plant wants

The fix

Water more evenly, move it away from radiators, and flush the pot with plain water every few months to wash out salts.

Read on

Brown crisp edges on the leaves

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

Rubber 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.