Why Plants Die
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Peace lily

Spathiphyllum wallisii, Araceae

Sources last read 14 September 2026.

Middling It gives warning, with time to act.

Also called Spathe Flower and white sails.

Peace lily (Spathiphyllum wallisii), the whole plant.
Bernard DUPONT from FRANCE, CC BY-SA 2.0 · Wikimedia Commons

Peace lily is toxic

  • Toxic to cats. Toxic principle: Insoluble calcium oxalates. Clinical signs: Oral irritation, pain and swelling of mouth, tongue and lips, excessive drooling, vomiting (not horses), difficulty swallowing. ASPCA
  • Toxic to dogs. Toxic principle: Insoluble calcium oxalates. Clinical signs: Oral irritation, pain and swelling of mouth, tongue and lips, excessive drooling, vomiting (not horses), difficulty swallowing. ASPCA
  • Toxic to people. Harmful when eaten; irritates skin and eyes. Use gloves and protective gear when handling it. RHS

What the sources say about its care

Sources file this plant under other names: Spathiphyllum (ASPCA), Spathiphyllum cv. Clevelandi (Clemson Extension). Citations below point at the name its source uses.

Light
Medium light 100–150 fc
Clemson Extension, filed as Spathiphyllum cv. Clevelandi · read 11 September 2026
Partial shade
RHS · read 11 September 2026
Water
Moist but well-drained
RHS · read 11 September 2026
Humidity

No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.

ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%
Penn State Extension · read 11 September 2026
Temperature

How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.

H1B — 10–15°C 10–15 °C
RHS · read 11 September 2026
Soil
Chalk, Loam, Sand; pH Acid or Alkaline or Neutral
RHS · read 11 September 2026
Toxic to cats
Toxic
ASPCA, filed as Spathiphyllum · read 11 September 2026
Toxic to dogs
Toxic
ASPCA, filed as Spathiphyllum · read 11 September 2026
Harmful to people
Harmful when eaten; irritates skin and eyes. Use gloves and protective gear when handling it.
RHS · read 11 September 2026

How it usually goes wrong

Brown tips on the newest leaves first

Leaves on the side of the peace lily nearest a heater or vent brown at the edges while those on the far side stay clean.

Penn State Extension cites ASHRAE's recommended indoor range of 30% to 60% relative humidity; a heated room in winter drops below it. Air that dry pulls water from the leaf faster than the roots replace it, and the margins are furthest from the supply.

Telling it apart: Where the plant stands. Browning concentrated on the side facing a heater points at the air.

Penn State ExtensionPeace lily brown leaf tips and edges: causes
Long bare stretches of stem between leaves

Nothing browns and nothing drops; the peace lily simply makes less, and what it makes is stretched and thin.

Its source places it in medium light. In less light than that the plant cannot fund full-sized leaves, so it makes smaller ones and spends the difference on stem.

Telling it apart: Turn the pot and wait a fortnight. New growth that swings back toward the window is answering a light question.

Clemson ExtensionPeace lily leggy, leaning growth: causes
Soft yellow leaves low on the plant, soil still wet

On a peace lily the yellowing climbs from below. Affected leaves feel limp rather than papery, and water sits in the saucer long after it drains through.

Its source calls for soil that is moist but well-drained. Past that, water in the pot displaces the air the roots need, and damaged roots then fail to supply the leaves above them.

Telling it apart: Whether the compost has dried at all since the last watering. A pot that has not dried in a fortnight is answering the question on its own.

RHSPeace lily leaves turning yellow: causes

Not sure which it is? Ask the diagnosis questions for Peace lily.

Routine care

Watering
Keep the soil moist without letting it get soggy, and let it dry between waterings. Peace lilies respond well to bottom watering.
NC State Extension, filed as Spathiphyllum · read 13 September 2026
While growing, water and mist generously and keep humidity high.
RHS · read 13 September 2026
Feeding
Feed at a quarter of the label strength, and flush the soil between feeds. Too much fertilizer and a build-up of salts can burn roots and leaf tips.
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Feed monthly with a balanced liquid fertiliser.
RHS · read 13 September 2026
Repotting
When needed, repot in February or March.
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Move to a larger pot once roots have outgrown the container.
RHS · read 13 September 2026
Propagation
By division.
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Divide in winter or straight after flowering.
RHS · read 13 September 2026
Pruning
Pruning is not needed.
RHS · read 13 September 2026
Pests and diseases
Usually free of pests and diseases.
RHS · read 13 September 2026

Move something and watch

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About the plant

Spathiphyllum wallisii, commonly known as peace lily, white sails, or spathe flower, is a very popular indoor house plant of the family Araceae. The genus name means "spathe-leaf", and the specific epithet is named after Gustav Wallis, the German plant collector. It was first described in 1877.

From Wikipedia, CC BY-SA 4.0 · read 13 September 2026

Native range
Colombia to Venezuela
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Mexico, Tropical America, Malesia, and Western Pacific
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Colombia C America
RHS · read 13 September 2026
Climate
wet tropical
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Growth form
perennial
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Herbaceous Perennial; habit erect, mounding, rounded
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Clump forming (evergreen)
RHS · read 13 September 2026
Size
Height 12–72 in; width 12–60 in
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Height 0.1-0.5 metres; spread 0.1-0.5 metres after 5–10 years
RHS · read 13 September 2026
Flowering
Flowers cream/tan, green, white
NC State Extension, filed as Spathiphyllum · read 13 September 2026
Flowers white in spring and summer
RHS · read 13 September 2026
Uses

What sources record people using this plant for. A traditional or medicinal use listed here is a record of use, not advice to eat it or treat anything with it.

The leaves are poisonous when eaten in large amounts.
NC State Extension, filed as Spathiphyllum · read 13 September 2026

Common problems with Peace lily

More of the Araceae family

Plants with similar care

Sources

What this does not cover

The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.

Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.

If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.