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Photo: Salil Kumar Mukherjee / CC BY-SA 4.0 / Wikimedia Commons
SucculentExotic

Pencil Cactus

Euphorbia tirucalli

Not a cactus: a bare, pencil-stemmed succulent spurge that grows into a small tree and shrugs off Dubai heat, but whose sap can burn skin and seriously injure eyes.

Mature size1–6 m tall, 1–3 m spreadGrowthModerateSunFull sunWaterVery low
Heat: 5 of 5
Salt: 4 of 5
Drought: 5 of 5
Shade: 2 of 5
Ease of care: 4 of 5
Use in a designGet it looked after

Every stem is full of white latex that is a severe irritant. It can burn skin, and in the eye it can cause serious injury, with temporary blindness reported and permanent corneal damage possible. Never prune, snap or move this plant without gloves, long sleeves and eye protection, and keep it away from children, pets, paths, play areas, pool decks and low windows. Its stems break easily, so site it where nobody will brush past it. If sap reaches the eye, rinse at once with plenty of clean water and get medical help promptly.

Season

Through the Dubai year

How Pencil Cactus behaves through Dubai's seasons, month by month.

J
F
M
A
M
J
J
A
S
O
N
D
24°
26°
29°
34°
38°
40°
42°
42°
40°
36°
31°
27°

Best planting window

Fresh growth at the tips

Mar – May

Shape in full protective gear

Mealybugs and scale in summer

Jun – Sep

  • Best planting window: Feb–Mar, Oct–Nov

    Wear gloves and eye protection to handle it; new plants benefit from afternoon shade in their first summer.

  • Fresh growth at the tips: Mar–May, Sep–Oct

  • Shape in full protective gear: Mar–Apr

    Gloves, long sleeves and eye protection; cut away from the face and let the latex dry before disposal.

  • Mealybugs and scale in summer: Jun–Sep

    Look in the joints between stems and treat early.

The pencil cactus is essentially evergreen in Dubai. New growth pushes from the stem tips in spring (March to May) and again in autumn when temperatures ease, and the stems keep their green through July and August highs of 40 °C and above. 'Sticks on Fire' forms take on coral tints in cooler weather and strong light. March and April are the time for any shaping, in full protective gear. Mealybugs are the main pest to watch for in summer. Cold is not a Dubai problem, though prolonged cold or wet is: NC State rates it as reliably hardy only in the warmest zones, and it rots in wet, heavy ground.

Meet the plant

Meet the Pencil Cactus

Meet the pencil cactus, the plant that looks like a thicket drawn in green pencil. There are no leaves to speak of and no flowers worth the name: just a mass of straight, slender stems, branching and rebranching until they make a soft, dense, fountain-like form that can stand several metres tall.

It is a plant for people who like structure over decoration. In a gravel bed against a wall, a single specimen gives height and a fine texture that is unlike anything else in a dry garden, a green haze by day and a sharp silhouette against uplighting at night. It shrugs off heat, drought and poor soil.

The cost is a rule: do not touch it casually. The white sap is a serious irritant, so this is a plant for the back of a bed, away from paths and play, planted deliberately and pruned carefully, with gloves and eye protection every time.

Euphorbia tirucalli is not a cactus. It is a spurge, in the family Euphorbiaceae, of African origin (Madagascar, East Africa and the Cape are all named in the literature), and it has become a common garden plant across the tropics. Its smooth, pencil-thick green stems carry out the photosynthesis; the tiny oval leaves, 1 to 2.5 cm long, appear on new growth and fall early, leaving a bare, branching mass of green sticks that can reach several metres in a warm climate. A published characterisation of the species notes high salinity and drought tolerance, qualities that suit Dubai.

The look is architectural: a dense, rounded or vase-shaped mass of fine green stems that casts light shade and reads as a soft haze by day and a sharp silhouette under uplighting at night. The cultivar sold as 'Sticks on Fire' or 'Firesticks' develops coral-red and orange tips in strong light and cool weather, and is the form most often grown for colour. Flowers are small and yellow, borne at the stem tips, and easy to miss.

The safety point is not optional. The white latex is highly irritant: NC State warns that it can cause mild to severe contact dermatitis, that eye contact can cause temporary to permanent corneal damage, and that ingestion blisters the lips and mouth. Stems snap easily, so a brush from a passing person or pet can release sap. The ASPCA lists the plant as toxic to dogs, cats and horses, though it notes that the effect by mouth is often over-rated; the real hazard is contact. Plant it well back from circulation. Crown of thorns is another Euphorbia with irritant sap, and the same handling rules apply to both.

Design

Where to use it

Specimen in gravelTall screen set well back from circulationLarge-container accent

Use pencil cactus as a deliberate specimen at the back of a large gravel bed or against a wall, at least 2 m from paths, pool decks, boundaries and play areas, where nobody will brush past it. In full sun and sandy, gritty soil it needs almost nothing. It works as a tall, fine-textured screen or a large-pot accent, but it is a poor choice for a clipped hedge along a walkway, since frequent trimming means frequent exposure to sap. Light it from below at night for a graphic silhouette.

A specimen of a Century plant (Agave americana) in the countryside within the neighbourhood of Mosqueira, north of th...

Agave

Agave's rigid, blue-grey rosette contrasts with the pencil cactus's fine, green, branching stems; both want sun, grit and very little water.

Full bloom during a rainy day

Crown of thorns

Another Euphorbia with irritant sap, so the two share handling rules and the same sharp-drainage, low-water care.

“Echinocactus grusonii”. Jardín de Cactus, Lanzarote

Golden Barrel Cactus

The golden barrel's solid sphere sits well below the pencil cactus's tall, airy mass, in the same dry bed.

Aloe vera (habit). Location: Maui, Kalepolepo

Aloe vera

Aloe's low rosettes and winter flower spikes give a soft base layer under the pencil cactus's stems, with similar water needs.

Care guide

How to grow it in Dubai

Watering

Summer: About every 10–14 days in the ground once established, more often in a pot; it tolerates drought and poor soil.

Winter: Every 3–4 weeks, or not at all after rain.

Establishment: Water every 5–7 days for the first month, then taper to every 2–3 weeks.

Soil
Free-draining, low-organic, sandy or gritty soil; waterlogging is the main hazard.
Feeding
None needed; a light, low-nitrogen feed in spring if growth is slow.
Pruning
Prune only with gloves, eye protection and long sleeves. Cut stems at a joint, point the cut end away from your face, let the latex dry before disposing of cuttings, and rinse tools after use. Never snap stems by hand.
Planting
Plant in October–November or February–March in full sun, in a gritty bed or large, heavy pot at least 2 m from paths, pool decks, boundaries and play areas. Wear gloves and eye protection when handling.
Pests
MealybugsScale insectsRoot rot in wet soil

Avoid these

Common mistakes

  • Pruning without eye protection. Sap can reach the face when a stem is cut or snapped, and the eye is the most serious risk; wear goggles, gloves and long sleeves.
  • Planting it beside a path, gate or play area. Stems snap when brushed, so give it at least 2 m of clearance from circulation.
  • Using it as a clipped hedge along a walkway. Frequent trimming means frequent exposure to the sap.
  • Treating it like a cactus in heavy, wet soil. It is a spurge and still rots in waterlogged ground, so plant it in a gritty bed.
  • Dumping cuttings where children or pets can reach them. The sap stays active; bag them and dispose of them with care.

Extra notes

Good to know

  • The common name is misleading: it is a spurge (Euphorbia), not a cactus, and its stems, rather than its leaves, do the photosynthesis.
  • NC State gives it as reliably hardy in USDA zones 11–12; Dubai's mild winters suit it, though prolonged cold or wet does not.
  • A published characterisation describes it as a drought- and salinity-tolerant plant that has been studied as a potential biofuel source.
  • It is used as a living fence or hedge in many tropical countries, but in a garden that people use, a clipped hedge means repeated exposure to the sap.

Toxicity: The sap is highly irritant. NC State warns that the milky latex can cause mild to severe contact dermatitis, that eye contact can cause temporary to permanent corneal damage, and that ingestion blisters the lips and mouth. The ASPCA lists it as toxic to dogs, cats and horses (irritant sap), noting that the effect by mouth is often over-rated. Wear gloves and eye protection when handling, and rinse any skin or eye contact with plenty of clean water; seek medical help promptly if the eye is affected.

Pros

  • Architectural mass of fine green stems that needs almost no care
  • Very drought tolerant and reported to tolerate salt well
  • Makes a tall specimen or screen in a large gravel garden
  • 'Sticks on Fire' forms add coral-red colour in strong light and cool weather
  • Few pests

Cons

  • Latex can burn skin and seriously injure eyes: gloves and eye protection are essential
  • Toxic to cats, dogs and horses, according to the ASPCA
  • Stems break easily and release sap, so keep it away from paths and pool decks
  • Grows large over time and is hard to remove safely

FAQ

Common questions

Is pencil cactus poisonous?
Yes. The ASPCA lists it as toxic to dogs, cats and horses, and the sap is a strong irritant to skin and eyes, with eye contact able to cause temporary to permanent corneal damage. Keep it away from children, pets and walkways.
Is pencil cactus a real cactus?
No. It is a spurge (Euphorbia, family Euphorbiaceae) from Africa. The 'cactus' in its name comes from its succulent, leafless look.
What should I do if the sap gets in my eye?
Rinse at once with plenty of clean running water for at least 15 minutes, do not rub, and get medical help promptly.
How much water does it need in Dubai?
Very little: about every 10–14 days in summer once established, and every 3–4 weeks in winter. It rots in wet soil.
How tall does it grow?
In warm climates it can reach several metres. In a Dubai garden expect 1 to 6 m over time, depending on pot size, water and pruning.

Not sure how it suits your garden?

Ask about Pencil Cactus on WhatsApp

Sources

  1. 1. NC State Extension Gardener Plant Toolbox: Euphorbia tirucalli
  2. 2. ASPCA: Pencil Cactus
  3. 3. University of Arkansas Extension: Plant of the Week, Pencil Cactus (Milkbush)
  4. 4. Euphorbia tirucalli L.: comprehensive characterization of a drought tolerant plant (PMC)
  5. 5. RHS: Euphorbia tirucalli

Last reviewed 2026-10-05 by Ghaf Gardens horticulture desk.

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