Euphorbia tirucalli ‘Sticks on Fire’ (Pencil Cactus)

Euphorbia tirucalli ‘Sticks on Fire’, commonly known as the Pencil Cactus, is a spectacular, drought-tolerant succulent known for its striking color and unusual growth habit. This cultivar of Euphorbia tirucalli features slender, branching stems that turn vivid shades of red, orange, and yellow, especially during cooler months. With its dramatic appearance and easy care, ‘Sticks on Fire’ is a popular choice for xeriscaping and modern landscape designs. Euphorbia tirucalli is prized by landscape designers who use it to add vertical accents in waterwise gardens, to create succulent seascapes, or to lend its fiery color to container floral displays.

Euphorbia tirucalli ‘Sticks on Fire’ – Pencil Cactus: An In-depth Look

Description

Euphorbia tirucalli ‘Sticks on Fire’ is an eye-catching, evergreen succulent shrub with thin, pencil-like stems that grow upright in a branching pattern. The plant’s most striking feature is its vibrant coloration, which ranges from bright red to fiery orange and yellow. This stunning color intensifies during cooler temperatures, particularly in winter, giving it the nickname “Firesticks”. Unlike many other succulents, ‘Sticks on Fire’ has very small, almost inconspicuous leaves that fall off shortly after appearing, leaving the colorful stems to take center stage. The plant’s smooth, cylindrical branches create a coral-like, architectural form, making it a striking addition to any garden or container.

Native Habitat

Euphorbia tirucalli is native to Africa, specifically in East Africa and parts of Madagascar, where it grows in arid, semi-desert regions. It has since spread to tropical and subtropical regions across the globe. The ‘Sticks on Fire’ cultivar has been adapted for ornamental use and is commonly found in warm, dry climates around the world, particularly in the southwestern United States.

Plant Type and Habit

Despite its common name, the Pencil Cactus is not a true cactus but belongs to the Euphorbiaceae family, which includes many popular plants such as poinsettia, croton, and crown of thorns.

The Pencil Cactus is a succulent shrub. It has a branching, upright habit, forming a thicket of slender, pencil-like stems. It often takes on a bushy, coral-like form as it matures.

Plant Size

Euphorbia tirucalli ‘Sticks on Fire’ is a relatively fast-growing plant that can reach a significant size, especially in ideal growing conditions: The plant typically grows to about 4-8 feet (1.2-2.4 meters) tall and wide, forming an impressive and colorful shrub. When grown in containers, it tends to stay more compact, usually around 2-3 feet (60-90 cm) tall.

Flowers

The flowers of this Pencil Cactus are very small and inconspicuous, usually appearing at the tips of the branches. These flowers are yellow-green and not considered a significant ornamental feature of the plant. Due to their small size, the flowers often go unnoticed, and the plant is prized more for its colorful stems than for its blooms. ‘Sticks on Fire’ blooms sporadically throughout the year, depending on the climate and growing conditions. In warmer regions, the plant may produce flowers during the spring and summer months, though the blooms are not a major highlight of this succulent.

Foliage and Stems

Euphorbia tirucalli ‘Sticks on Fire’ has very few leaves. The leaves are small, narrow, and ephemeral, typically appearing on new growth before quickly dropping off. As a result, the plant’s foliage is not its main attraction.

Providing year-round interest, the stems are slender, cylindrical, and resemble brightly colored pencils. These smooth, upright stems are primarily yellow-green but turn vivid shades of red, orange, and pink during cooler months or under bright sunlight, giving the plant its “fire” appearance. The stems are succulent, allowing the plant to store water and thrive in dry conditions. Over time, the lower parts of the stems may harden and turn woody, supporting the plant’s bushy, coral-like structure.

Hardiness

The Pencil Cactus is hardy in USDA zones 10-12, meaning it thrives in warm climates and is frost-sensitive. It can tolerate temperatures down to around 50°F (10°C), but prolonged exposure to cold temperatures or frost can damage or kill the plant. In colder regions, it can be grown in containers and moved indoors during the winter.

Uses

Euphorbia tirucalli ‘Sticks on Fire’ has a range of uses in both landscaping and indoor gardening:

• Ornamental plant: It is often used in rock gardens, xeriscapes, and desert gardens, where its bright color provides contrast to other plants.
• Container plant: ‘Sticks on Fire’ is popular for growing in pots and containers, making it an excellent choice for patios, terraces, and sunny indoor spaces.
• Drought-tolerant gardens: Its ability to withstand extreme drought makes it a valuable addition to low-water gardens and sustainable landscapes.

Wildlife

The Pencil Cactus does not play a significant role in supporting wildlife compared to other garden plants.

Toxicity

The pencil Cactus contains a milky white sap toxic to pets and humans. Contact with the sap can cause severe skin irritation, rashes, blistering, and eye injuries, potentially leading to temporary blindness if it gets into the eyes. If ingested, the sap can cause nausea, vomiting, and gastrointestinal distress. It’s important to handle this plant with care, wearing gloves and avoiding contact with the sap.

Deer and Rabbit Resistance

The toxic sap makes it highly resistant to deer and rabbits. These animals tend to avoid plants with irritating or harmful compounds, so ‘Sticks on Fire’ is a good choice for gardens where wildlife can be a problem.

Drought Tolerance

The pencil Cactus is drought-tolerant, making it ideal for arid climates and water-wise gardening. Once established, the plant requires very little water and can survive extended periods without rainfall.

Invasiveness

Euphorbia tirucalli is not considered invasive in most regions where it is cultivated, but in tropical climates, it has been known to spread if not managed properly. The plant reproduces vegetatively by cuttings and stem fragments. Currently, this species is listed as invasive in Hawaii and Cuba and is potentially invasive on many islands in the Pacific and tropical and subtropical areas of Asia.

Pencil Cactus Care

The Pencil Cactus is an easy-to-care-for succulent that thrives in a variety of conditions.

Light Requirements

Pencil Cactus thrives in bright, direct sunlight. It requires at least 6 hours of direct sunlight daily to maintain its vibrant colors, especially the ‘Sticks on Fire’ variety. If grown indoors, place it near a south or west-facing window. Insufficient light may cause the plant to lose its vivid colors and become leggy.

Soil Requirements

• Soil: Use a well-draining cactus or succulent mix. You can also create your own mix by combining regular potting soil with sand, perlite, or pumice to ensure good drainage.
• Containers: If planting in a pot, ensure it has drainage holes to prevent water from accumulating at the roots, which can cause root rot.

Watering

• Watering Frequency: Water your Pencil Cactus sparingly. Allow the soil to dry out completely between waterings. During the growing season (spring and summer), water approximately once every 2-3 weeks. In the dormant period (fall and winter), reduce watering to once a month or less.
• Overwatering: Overwatering can lead to root rot, so make sure to avoid letting the plant sit in soggy soil.

Temperature and Humidity

• Temperature: The Pencil Cactus prefers warm temperatures and is hardy in USDA zones 10-12. It thrives in temperatures ranging from 65°F to 75°F (18°C to 24°C) but can tolerate temperatures down to 50°F (10°C) for short periods.
• Humidity: Pencil Cactus is drought-tolerant and does not require high humidity. It does well in typical indoor conditions.

Fertilizing

Pencil Cactus doesn’t require much fertilization. Feeding it once in the spring with a balanced, diluted liquid houseplant or cactus fertilizer is generally sufficient for the entire year. Avoid over-fertilizing, as this plant thrives in nutrient-poor conditions, and excess nutrients may harm its growth.

Pruning

Prune your Pencil Cactus to control its shape and size. Use gloves and handle it carefully, as the plant’s milky white sap is toxic and can cause skin irritation.

Repotting

Repot your Pencil Cactus every 2-3 years or when it outgrows its container. Use fresh, well-draining soil during repotting, and choose a slightly larger pot if necessary.

Propagation

Propagate your Pencil Cactus through stem cuttings. Allow the cuttings to dry and callous for a few days before planting them in well-draining soil. Water sparingly until roots form.

Pests and Diseases

The Pencil Cactus can be affected by pests such as mealybugs, spider mites, and aphids, which weaken the plant by feeding on its sap. If infestations occur, treat them with neem oil.

Common diseases include root rot, often caused by overwatering, and powdery mildew or botrytis, which thrive in high humidity and poor ventilation. To prevent these issues, ensure proper watering, well-draining soil, good air circulation, and regular inspection for pests. Treat infestations with neem oil or insecticidal soap when necessary.