Zantedeschia 'Black Star' (Black Star calla lily) care

Light

In the wild zantedeschia 'black star' grows on the bright edge of a forest canopy, not in the canopy and not in the open. Indoors, that translates to within a metre of an unobstructed window, sheer curtain optional. Bright filtered light indoors or full sun to part shade outdoors brings out the darkest spathe colour. Deep shade fades the colour and weakens the stems; very intense heat and sun can scorch leaf edges. The fastest test: a hand held at the leaf casts a soft-edged shadow at noon — sharp shadow means too much sun, no shadow means too little light.

Watering

Aim for when the top 2-3 cm of soil is dry, roughly every 5-7 days in active growth for zantedeschia 'black star', but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Maintain evenly moist compost while in leaf and flower, allowing the surface to dry slightly between waterings. Never let the pot stand in water. Reduce sharply after blooming and store the rhizome almost dry over winter.

Soil and pot

Zantedeschia 'Black Star' grows best in fertile, moisture-retentive but well-drained potting mix. A peat-free multipurpose compost amended with grit or perlite, slightly acidic to neutral (pH 6.0-6.5). Good drainage is critical to prevent rhizome rot in these coloured hybrids. 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

Zantedeschia 'Black Star' sits happiest at around 40-60% humidity and 15-24°C (59-75°F). Ordinary room humidity is fine. Moderate humidity keeps foliage healthy, but keep water off the spathes to avoid spotting and grey mould. If you keep the room above 15 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 zantedeschia 'black star' sparingly. Apply a high-potassium liquid feed every 2-3 weeks during active growth to maximise the dark blooms. Go easy on nitrogen-heavy feeds, which favour foliage over flowers. Cease feeding as the plant yellows into dormancy. 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 zantedeschia 'black star' in the Growli community. Each is annotated with the most common cause so you know where to start.

• Rhizome rot — Soggy or cold compost rots the rhizome; use free-draining mix, avoid overwatering, and store dry during dormancy.
• Faded spathe colour — Insufficient light dulls the signature near-black tone; give brighter indirect light or more sun for the deepest colour.
• Botrytis (grey mould) — Water sitting on spathes and crowded, humid conditions invite grey mould; improve airflow and water at the base only.
• Spider mites — Hot, dry indoor air encourages fine webbing and stippled leaves; raise humidity slightly and treat early with insecticidal soap or a miticide.

Propagation

Lift and divide rhizomes in early spring or at dormancy, keeping a healthy eye on each piece; pot in fresh free-draining mix and water sparingly until new growth begins. Hybrids will not come true from seed. 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

Zantedeschia 'Black Star' is toxic to pets. Toxic to cats and dogs. The ASPCA classifies calla lily (Zantedeschia) as toxic because of insoluble calcium oxalate crystals throughout the plant; chewing causes oral and lip irritation, burning, drooling, vomiting and difficulty swallowing. Keep out of reach of pets. 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.

Zantedeschia 'Black Star' deep-dive guides

Every aspect of zantedeschia 'black star' care, each with its own calibrated guide:

• Zantedeschia 'Black Star' watering schedule
• Zantedeschia 'Black Star' light requirements
• Best soil mix for zantedeschia 'black star'
• Zantedeschia 'Black Star' fertilizing guide
• When to repot zantedeschia 'black star'
• How to propagate zantedeschia 'black star'
• Zantedeschia 'Black Star' growth rate & size
• Zantedeschia 'Black Star' cold hardiness
• Zantedeschia 'Black Star' temperature & humidity
• Is zantedeschia 'black star' toxic to cats & dogs?
• Is zantedeschia 'black star' toxic to cats?
• Is zantedeschia 'black star' toxic to dogs?
• Getting zantedeschia 'black star' to bloom

Featured in these plant shortlists

Zantedeschia 'Black Star' qualifies for 3 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best flowering houseplants — Indoor plants grown for their blooms — selected from the flowering species in Growli’s plant-care library.
• Houseplants toxic to cats & dogs — The common houseplants the ASPCA lists as toxic to cats and dogs — the ones to keep out of reach, each with its symptoms and a safe alternative.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Zantedeschia 'Black Star' is also commonly called Black Star calla lily or dark purple calla.

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