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Araceae

Anthurium

The largest genus in the arum family — Kew accepts 1,459 species — and not one thing horticulturally: it splits between the glossy flamingo flowers grown for their blooms and the velvet-leaved species grown for foliage, which want quite different treatment. Some are epiphytes, some terrestrial, some climbing hemiepiphytes. The genus-specific risk is bacterial blight, which is incurable, often latent in a new plant, and spreads in water sitting on a leaf.

Native to Mexico through tropical America to Paraguay and northern Argentina, and the Caribbean

How Anthurium generally wants to be treated

Plant care

Species pages start from this and record only where they differ.

Light
Bright indirect, never direct midday sun. Commercial production runs at 1,000-2,500 foot-candles under heavy shade; indoors the useful band is 100-500 foot-candles, and 100 is a floor rather than a target — plants hold on there but do little.
Water
Water when the top 5 cm is approaching dry, and never leave the pot standing in water. Keep water off the foliage: the blight bacterium swims across a wet leaf surface, so raising ambient humidity and misting are different acts with opposite effects.
Humidity
High — 70 to 80 per cent is the only figure any university publishes, and it is for commercial flamingo flowers rather than the velvet species. Do not chase 90 per cent and above: transpiration stops in saturated air, which strands calcium and invites rot. Nobody has published a number for the velvet-leaved species at all.
Temperature
65-85 °F (18-29 °C) all year, with a hard floor around 55 °F (13 °C). They do not want a cool winter rest and will not thank you for one.
Substrate
Coarse and largely soil-free — bark and perlite with only a minority of fines, at pH 6.0-6.5. The roots carry a velamen, the same absorptive sheath orchid roots have, which is the anatomical reason a dense mix suffocates them.
Fertilizer
Weak and frequent: a balanced feed at about 50 ppm nitrogen monthly indoors. Scale the rate to the light rather than the calendar — a plant in a dim room on a summer schedule is being over-fed.
Propagation
Division and offsets are reliable. Stem cuttings work on the species that build a visible stem with aerial roots. Seed must be sown fresh and takes around three years to flower. Sterilise the blade between plants, every time.
Dormancy
None. Growth slows in low winter light — water and feed less, but keep them warm.
Common problems
  • Bacterial blight: yellow V-shaped lesions spreading from the leaf margin, then blackening. There is no cure, it can sit latent for months in a healthy-looking new plant, and it is the reason to quarantine and to never reuse an uncleaned blade
  • Brown crisp leaf tips are usually dry air or accumulated fertiliser salts rather than underwatering
  • Thrips leave stippled silvery new growth; scale and mealybugs hide where the petiole meets the stem
  • Collapse at the base with soft brown roots is rot — Pythium, Phytophthora or Rhizoctonia — and almost always follows a dense mix or a pot left standing in water
  • No flowers on a flowering type means too little light, though the foliage species are not grown for flowers at all
  • Every part carries calcium oxalate crystals: the sap irritates skin and eyes, and a chewed leaf burns the mouth

Sources 12345678

In the collection