How to care for a peace lily (spathiphyllum)

The peace lily has a virtue no other houseplant has: it faints when it runs out of water. The leaves droop dramatically, you water it, and two hours later it's standing tall again. For someone just starting out, it's a built-in warning system.

The basics

• Light: medium to low, indirect. It's one of the few that genuinely tolerates a dim room. Never direct sun: it scorches the leaves.
• Water: once a week in summer, every ten to fifteen days in winter. Or simply when it faints.
• Humidity: it's tropical. Mist the leaves or set the pot on a tray of pebbles and water (without the bottom of the pot touching the water).
• Temperature: between 18 and 27°C (64 to 81°F). Below 12°C (54°F) it suffers.

A note about the fainting: it works as an occasional warning, not as a method. If you let it get to that point every week, it weakens and the leaf tips turn brown.

Why it doesn't bloom

It's the most frequent question. Three causes, in order:

1. Not enough light. It tolerates dimness, but to bloom it needs plenty of indirect light. That's the reason in most cases.
2. Not enough fertilizer. In spring and summer, liquid fertilizer for flowering plants every 15 days. No nutrients, no flowers.
3. A pot that's too big. Peace lilies bloom best when slightly root-bound. If you repotted it into something much bigger, it will make leaves for a year and not a single flower.

Brown tips

It's the classic peace lily problem, and it's almost always the chlorine and fluoride in tap water. The fix costs nothing: let the water sit in an open jug for 24 hours before watering. It can also be dry air or too much fertilizer.

About "purifying the air"

It shows up on every list of air-purifying plants, thanks to a 1989 NASA study. That study was done in sealed laboratory chambers, not in a living room. In a real room it would take an absurd number of plants to move the needle. We go into it in air-purifying plants. Keep one because it's beautiful and easy, which is plenty.

Warning

It's toxic if ingested, like all aroids. It irritates the mouth and throat in people and pets.