Houseplantfoliage houseplantSome care needed

Dieffenbachia

Dieffenbachia seguine

Before you grow or eat this

The sap is strongly irritant. Chewing any part causes immediate intense burning, profuse drooling, swelling of the mouth and tongue and temporary loss of speech — the origin of the name dumb cane. Severe swelling can obstruct the airway, which is why this is rated above the other oxalate aroids. Do not grow it within reach of small children or pets that chew plants. If chewed, rinse the mouth and offer water, and seek medical or veterinary advice immediately if there is any swelling affecting breathing or swallowing.

A big-leaved aroid grown for bold variegation, and the houseplant with the most consequential sap in common cultivation. The common name records what the sap does: severe oral irritation and temporary loss of speech.

Position: Bright, out of direct sun
Water: moderate demand
Drainage: Free-draining
Grows to: 90–180 cm × 60–90 cm
Frost: Frost tender
Difficulty: Some care needed

August

Nothing to do

No sowing, planting, harvesting or pruning window falls in August.

Dieffenbachia’s year

Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.

Activity	J	F	M	A	M	J	J	A	S	O	N	D
Prune				April.	May.

Timing that travels

The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.

Conditions it needs

Light: Partial shade, Dappled shade
Frost: Frost tender
Grows best at: 18–27 °C
Soil: Peat-free compost
Soil pH: 5.5–6.5
Drainage: Free-draining
Water needs: moderate
Drought: poor tolerance
Waterlogging: poor tolerance
Heat: good tolerance
Wind and exposure: poor tolerance

Where these figures come from

LightSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — position
Checked 2026-08-13
FrostSourced guidancehigh confidence: Royal Horticultural Society: Dieffenbachia — hardiness
Checked 2026-08-13
Grows best atSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — temperature
Checked 2026-08-13
SoilSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — soil
Checked 2026-08-13
Soil pHSourced guidancemoderate confidence: Plant Finder — Missouri Botanical Garden: Dieffenbachia seguine — culture
Checked 2026-08-13
DrainageSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — soil
Checked 2026-08-13
Water needsHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
DroughtHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
WaterloggingHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
HeatHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Wind and exposureHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

On your soil

Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.

Soil	Verdict	Why
Heavy clay	Works, with one condition	Dieffenbachia will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Sandy	Works, with one condition	Dieffenbachia will crop on sandy, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure.
Chalky and alkaline	Struggles here	Dieffenbachia struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely.
Loam	Grows well here	Dieffenbachia grows perfectly well on loam without special measures, though it is not the soil it would choose.
Silty	Grows well here	Dieffenbachia grows perfectly well on silty without special measures, though it is not the soil it would choose.
Peaty and acid	Works, with one condition	Dieffenbachia will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Shallow over rock	Works, with one condition	Dieffenbachia will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure.
Made ground and urban soil	Struggles here	Dieffenbachia struggles on made ground and urban soil: The soil is substantially too alkaline for it: it wants pH 5.5 to 6.5, and this soil sits around 7.2 to 7.8. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy. A container or a raised bed of imported soil sidesteps the problem entirely.

Not sure which you have? Four hand tests will settle it.

Space and spacing

Mature height: 90–180 cm
Mature spread: 60–90 cm
Rooting depth: 25 cm

Where these figures come from

Mature heightHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Mature spreadHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Rooting depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

In a container

Minimum volume: 5 litres or more
Minimum depth: 20 cm

Where the container figures come from

Minimum volumeHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Minimum depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Where and how you can grow it

Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.

Method	Suitability	What it needs
Indoor pot	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Container	Well suited source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13	Indoors, or outdoors in summer only
Windowsill	Marginal source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13
Open ground	Not suitable source Sourced guidancemoderate confidence Royal Horticultural Society: Growing method suitability Checked 2026-08-13	Tender: will not survive a British winter outdoors.

Growing it

PruningWear gloves and wash your hands afterwards. The sap causes severe irritation to the mouth, eyes and skin, and cutting a stem releases a great deal of it.
ProtectionTurn the pot regularly. Dieffenbachia leans hard towards its light source and, being top-heavy, an unturned plant eventually falls over rather than merely looking lopsided.
WateringThorough, and then leave it alone until the top two or three centimetres are dry; always empty the saucer. The thin leaves have few reserves so it wilts sooner than most, but it also rots readily at the base if left standing wet in a cool room. Reduce from October. The classic winter failure is a plant by a cold window watered on a summer habit — the lowest leaves yellow and drop, the stem goes soft at soil level, and the plant is usually past saving by then. Wear gloves when cutting it: the sap is a serious irritant to skin, eyes and mouth.
FeedingMonthly at half strength through spring and summer, nothing from October to March. Dieffenbachia grows quickly in warmth and good light and rewards feeding with big leaves; in poor light it grows anyway, but tall and thin with a bare lower stem, and feeding accelerates that rather than fixing it. A leggy plant is cut back hard in spring — it reshoots readily from the stump, and the cut top roots easily.

Where this guidance comes from

PruningSourced guidancehigh confidence: Royal Horticultural Society: Dieffenbachia — handling
Checked 2026-08-13
ProtectionSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — cultivation
Checked 2026-08-13
WateringSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — cultivation
Checked 2026-08-13
FeedingSourced guidancemoderate confidence: Royal Horticultural Society: Dieffenbachia — cultivation
Checked 2026-08-13

The bud you cut to becomes the new shoot, and it grows in the direction it points — which is why an outward-facing bud opens the plant up and an inward-facing one crosses the middle.

What goes wrong

Problem	How often	Notes
Aphids	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13

Safety and edibility

Cats and dogsCan be dangerous — treat as urgent

Listed as harmful to cats or dogs

Dieffenbachia is listed as harmful if eaten. The sap carries insoluble calcium oxalate crystals at higher concentration than the other common aroids, together with proteolytic enzymes. Chewing causes immediate intense burning and swelling of the mouth, tongue and throat, and the swelling can be severe enough to interfere with swallowing or breathing.

source

Sourced guidancehigh confidence

ASPCA Animal Poison Control Center — toxic and non-toxic plant list — American Society for the Prevention of Cruelty to Animals: Dieffenbachia seguine — toxic plants list
Veterinary Poisons Information Service — VPIS, London: Dieffenbachia seguine — clinical effects

Checked 2026-08-13

Affected parts: all parts, sap.

Pets and livestockpetschildren
The sap is strongly irritant. Chewing any part causes immediate intense burning, profuse drooling, swelling of the mouth and tongue and temporary loss of speech — the origin of the name dumb cane. Severe swelling can obstruct the airway, which is why this is rated above the other oxalate aroids.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Dieffenbachia seguine — toxicity
- Plant Finder — Missouri Botanical Garden: Dieffenbachia — toxicity
Checked 2026-08-13
Do not grow it within reach of small children or pets that chew plants. If chewed, rinse the mouth and offer water, and seek medical or veterinary advice immediately if there is any swelling affecting breathing or swallowing.

Sources for this page

GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society

Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-14.