Peace lily

The peace lily grows on the forest floor of tropical America, in the deep shade under a closed canopy where the air stays humid and the leaf litter never quite dries out. That explains both halves of its character indoors: it tolerates far less light than most flowering plants, and it has no patience at all with dry air or a dry pot. Give it a steady supply of water, a humid room and a little more light than it strictly needs, and it will put up white spathes twice a year.

Light

It survives in low light, which is why it is sold as a plant for dark corners, but surviving and flowering are different things. For flowers it wants medium indirect light: a few metres from a bright window, or right beside a shaded one. If a mature plant has stopped flowering, light is the first thing to change and usually the only thing that needs changing.

Direct sun is the other extreme. An hour of it through glass leaves pale bleached patches on the leaves that do not recover.

Water

This is the one common houseplant that prefers its compost lightly moist rather than dried out between waterings. Water when the top two centimetres are dry, thoroughly, until it runs from the base, and empty the saucer afterwards. In a warm room that is roughly every five days in summer and weekly in winter.

It tells you when it is thirsty by collapsing, and it stands back up within a few hours of a drink, which makes it look like a forgiving plant. It is not quite. Every full wilt kills a few roots and browns a few leaf tips, and a plant that is allowed to collapse regularly slowly declines. Water it before it asks.

Hard tap water is worth avoiding. Where the water is hard, the leaf tips brown steadily whatever else you do, and rainwater or filtered water fixes it within a season of new growth.

Humidity

Dry air is the second half of the problem. A bathroom or a kitchen suits it, and in a dry living room it appreciates a tray of wet pebbles under the pot or a group of other plants around it. Misting helps for an hour and is not a substitute for either.

Feeding and repotting

Feed little and often: a balanced liquid feed at a quarter to a half of the recommended strength, monthly through spring and summer, and nothing in winter. Overfeeding is visible on this plant in a way it is not on most, as green flowers and brown leaf tips.

Repot in spring every second year, one size up only. A peace lily flowers better slightly potbound, and a pot too large holds wet compost the roots cannot reach, which is how a plant that likes moisture still manages to rot.

Pruning and propagation

Cut spent flower stalks right down at the base once the spathe has gone green and then brown, and take off yellowing leaves at soil level. Wipe the leaves occasionally; they are broad and collect dust.

Divide it at repotting. Tip the plant out, find the natural crowns where several leaves rise from one point, and pull or cut the clump into pieces each with three or four leaves and its own roots. Pot them separately, keep them damp and out of direct light for a fortnight, and they establish quickly. Cuttings do not work, because there is no stem to cut.

Ailments

Drooping is thirst and is fixed in an afternoon. Brown tips are hard water, dry air or overfeeding, in that order of likelihood. Green flowers mean too much feed. Yellow lower leaves on a plant in wet compost mean the roots are drowning, which is the one thing that will actually kill it. The ledger below has the rest.