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Plant care

Arum Lily (Calla Lily) care

Zantedeschia aethiopica

Also called Arum Lily, Calla Lily, White Calla, Pig Lily.

RHS H4USDA 8-11Toxic to petsIndoor 90–120 cm (3–4 ft) tall and 60–90 cm (2–3 ft) wide at full maturity.

Watering rhythm

2-3days

Regularly moist to wet — water every 2–3 days or plant in standing water

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Light

Bright indirect light (just back from a sunny window)

Soil

Moist, fertile loam or aquatic marginal compost

Humidity

Moderate to high (50–80%)

Temp

-5°C to 30°C

Pet safety

Toxic to pets

Mature size

90–120 cm (3–4 ft) tall and 60–90 cm (2–3 ft) wide at full maturity.

Care at a glance

Light

Bright but filtered. Arum Lily burns within days in unfiltered south-facing summer sun, and stops growing within months in deep shade. Performs best in full sun in cool-summer climates and prefers afternoon shade in areas with hot summers; deep shade reduces flowering significantly — aim for 4–6 hours of direct or bright indirect light daily. If you only have a south window, set the plant back 1.5 m or hang a sheer curtain — both knock the intensity down into the right range.

Watering

Watering arum lily: regularly moist to wet — water every 2–3 days or plant in standing water. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Naturally a wetland species that tolerates roots sitting in up to 30 cm of water; keep soil consistently moist during the growing season and reduce watering in winter to prevent rhizome rot.

Soil and pot

Arum Lily grows best in moist, fertile loam or aquatic marginal compost. Plant in rich, moisture-retentive soil or in aquatic baskets of heavy loam at pond margins; amend with generous organic matter and avoid sandy or fast-draining soils that cause drought stress. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Arum Lily sits happiest at around Moderate to high (50–80%) humidity and -5°C to 30°C (23°F to 86°F). Appreciates higher humidity as a wetland native; in hot, dry climates grow near water features or mist foliage during dry periods to maintain leaf gloss and reduce transpiration stress. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed arum lily sparingly. Feed every 2–3 weeks from spring until flowering ends with a high-potassium liquid fertiliser (tomato feed is ideal) to support large, waxy flowers; stop feeding once foliage yellows in late summer. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on arum lily in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Rhizome Rot — Overwatering in cool or waterlogged conditions during winter dormancy causes fungal rot of the rhizome; allow soil to dry slightly between waterings from autumn onward and ensure good drainage outside the growing season.
  • Botrytis (Grey Mould) — Dense, humid conditions in mild wet weather encourage Botrytis cinerea on foliage and flowers; improve air circulation, remove affected material promptly, and avoid overhead watering.
  • Thrips — Western flower thrips cause silvery streaking on leaves and flower distortion in greenhouse or conservatory-grown plants; treat with an appropriate insecticide or introduce Amblyseius cucumeris as a biological control.

Propagation

Divide rhizomes in spring, ensuring each section has at least one growing eye; can also be grown from offsets removed in autumn, or from seed sown at 21°C (70°F) in spring, though seed-grown plants take 2–3 years to flower. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Arum Lily is toxic to pets. Zantedeschia aethiopica is confirmed toxic to cats and dogs by the ASPCA (listed on the ASPCA Toxic and Non-Toxic Plant database). The toxic principle is insoluble calcium oxalate crystals (raphides) present in all parts of the plant. Clinical signs include intense oral irritation, pain and swelling of the mouth, tongue, and lips, excessive drooling, vomiting, and difficulty swallowing. Seek veterinary attention immediately if ingestion is suspected. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Arum Lily care — frequently asked questions

What is the common name for Zantedeschia aethiopica?

Zantedeschia aethiopica is most commonly called Arum Lily, but it is also known as Arum Lily, Calla Lily, White Calla, Pig Lily. The names refer to the same species, so care instructions for Arum Lily apply identically to anything sold as Calla Lily.

How much light does arum lily need?

Arum Lily grows best in bright indirect light (just back from a sunny window). Performs best in full sun in cool-summer climates and prefers afternoon shade in areas with hot summers; deep shade reduces flowering significantly — aim for 4–6 hours of direct or bright indirect light daily.

How often should I water arum lily?

Water arum lily regularly moist to wet — water every 2–3 days or plant in standing water. Naturally a wetland species that tolerates roots sitting in up to 30 cm of water; keep soil consistently moist during the growing season and reduce watering in winter to prevent rhizome rot. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is arum lily toxic to cats and dogs?

Arum Lily is toxic to pets. Zantedeschia aethiopica is confirmed toxic to cats and dogs by the ASPCA (listed on the ASPCA Toxic and Non-Toxic Plant database). The toxic principle is insoluble calcium oxalate crystals (raphides) present in all parts of the plant. Clinical signs include intense oral irritation, pain and swelling of the mouth, tongue, and lips, excessive drooling, vomiting, and difficulty swallowing. Seek veterinary attention immediately if ingestion is suspected.

What USDA hardiness zone does arum lily grow in?

Arum Lily is rated for USDA zone 8-11 and RHS hardiness H4. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Arum Lily deep-dive guides

Every aspect of arum lily care, each with its own calibrated guide:

Featured in these plant shortlists

Arum Lily qualifies for 6 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Arum Lily is also known as Arum Lily, Calla Lily, White Calla, and Pig Lily.