Houseplants

Dumb cane

DieffenbachiaAraceae
Also: Dieffenbachia, Leopard lily
AT A GLANCE
Bright indirect light Water: average H1aheated glasshouse 60 cm–1.2 m tall · 40–60 cm wide In a pot: yes

The common name 'dumb cane' refers to the temporary loss of speech that can follow chewing the sap-filled leaves or stems, due to painful swelling of the mouth and throat — the most severe household toxicity risk among this KB's aroid houseplants, so site it out of reach of pets and young children rather than merely being mindful.

Care

Light

Tolerates medium light, but variegated leaf patterns are more pronounced in brighter conditions.

Water

Water when the top few centimetres of compost have dried out; sensitive to both overwatering and prolonged drought.

Soil

Peat-free, free-draining houseplant compost.

Pruning

Remove yellowing or damaged lower leaves at the base; a leggy plant can be cut back hard in spring and will usually resprout from the cut cane.

Feeding

A balanced feed at half strength monthly in the growing season. Nothing in winter — a plant in low light with wet compost and fertiliser is the standard route to soft, collapsing stems.

Propagation

Cut the bare cane into 10cm sections and lay them horizontally on warm, damp compost, or root the leafy top as a cutting. The sap is an irritant, so wear gloves and keep the work away from children and pets.

Month by month

Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.

  1. MarchResume feeding monthly as growth picks up. how ›
  2. AprilA good time to cut back a leggy, bare-stemmed plant if wanted — it typically resprouts readily from the cane. how ›
  3. OctoberReduce watering as growth slows for the cooler months. how ›

Months based on climate: UK. Your choice stays on this device.

  1. MarchResume feeding monthly as growth picks up. how ›
  2. AprilA good time to cut back a leggy, bare-stemmed plant if wanted — it typically resprouts readily from the cane. how ›
  3. OctoberReduce watering as growth slows for the cooler months. how ›

Months based on climate: Northern Italy. Your choice stays on this device.

  1. MarchResume feeding monthly as growth picks up. how ›
  2. AprilA good time to cut back a leggy, bare-stemmed plant if wanted — it typically resprouts readily from the cane. how ›
  3. OctoberReduce watering as growth slows for the cooler months. how ›

Months based on climate: Central Italy. Your choice stays on this device.

  1. MarchResume feeding monthly as growth picks up. how ›
  2. AprilA good time to cut back a leggy, bare-stemmed plant if wanted — it typically resprouts readily from the cane. how ›
  3. OctoberReduce watering as growth slows for the cooler months. how ›

Months based on climate: Southern Italy and islands. Your choice stays on this device.

Common problems

Severe mouth and throat irritation if chewed

How to spot it. Not a plant health problem, but the household safety issue the common name refers to.

What to do. The sap contains calcium oxalate crystals that cause intense burning and swelling if the leaves or stems are chewed — keep well away from pets and young children; this is more severe than most other aroids in this KB.

Lower leaves yellowing and dropping

How to spot it. Oldest, lowest leaves fade and fall while new growth is healthy.

What to do. Often natural ageing; if it happens rapidly or affects many leaves at once, check watering isn't excessive.

Bare, leggy stem

How to spot it. Leaves only near the top of an increasingly tall, bare cane.

What to do. A natural growth habit over time — cut back hard in spring to encourage bushier regrowth from lower on the stem.

Questions

Dumb cane: is it hardy?

H1a: True houseplant, needs above 15°C. It survives heated glasshouse.

Can it grow in a pot?

Grown exclusively as a pot plant in the UK climate.

Dumb cane: when do you prune it?

Remove yellowing or damaged lower leaves at the base; a leggy plant can be cut back hard in spring and will usually resprout from the cut cane.

When do you feed it?

A balanced feed at half strength monthly in the growing season. Nothing in winter — a plant in low light with wet compost and fertiliser is the standard route to soft, collapsing stems. Feeding months, UK: April–September.