Pencil Cactus / Sticks on Fire
Euphorbia tirucalli
description
Pencil Cactus is a branching succulent with slim pencil-like green stems and caustic sap.
benefits
- Low—water tolerant
- Сan handle lower humidity level
- Drought-tolerant — forgives missed waterings
- Low maintenance
- Suitable for containers
warnings
- Toxic to cats
- Toxic to dogs
How to care for Pencil Cactus
sunlight
Native to dry, open parts of Africa, Pencil Cactus grows with plenty of sun. Give it the brightest spot you have indoors, ideally close to a south or west-facing window.
Bright indirect light
This is tolerated, especially for green forms, but growth may become sparse if the plant sits far from a window. Keep it within a few feet of bright glass.
Direct sun
Several hours of direct sun suits an established plant. Acclimate it over 1-2 weeks when moving it into stronger light, especially in summer. The 'Sticks on Fire' cultivar needs strong sun to keep its orange-red color.
watering
Let the potting mix dry out completely before watering. Pencil Cactus stores water in its stems, so soggy roots are far riskier than a short dry spell.
Spring through early fall
In active growth, water roughly every 2-4 weeks indoors. Soak the soil thoroughly until water drains out, then wait until it is dry all the way through the root ball before watering again.
Cooler, lower-light months
Water about every 4-8 weeks, and only when the mix is completely dry. Growth slows in cool or dim conditions, so the plant uses much less water.
Bright heat, a small terracotta pot, and a gritty mix dry faster. Low light, cool rooms, a large pot, or dense soil can extend the wait considerably.
humidity
Preferred humidity
Native to dry parts of Africa, Pencil Cactus is comfortable in average household air and does not need misting or a humidifier. It tolerates humidity down to about 20% when watered appropriately.
Very dry air can contribute to slight stem wrinkling or shriveling, but check the potting mix first: underwatering is the more likely cause. Avoid consistently humid, stagnant conditions, which can encourage rot.
temperature
Preferred range
Winter minimum
Native to warm, dry parts of Africa, Pencil Cactus is happiest in steady indoor warmth. It handles dry heat well, but cold slows growth and can damage its water-filled stems. Keep it away from chilly windows and bring outdoor plants inside before nights fall below 10°C (50°F).
nutrition
March - August
Feed about once a month while it is actively making new stems, using a liquid cactus or succulent fertilizer at half the label strength. Apply to already-moist soil. Skip fertilizer in autumn and winter, or whenever growth has slowed in low light.
Nitrogen
Nitrogen supports the green, pencil-like stems. A diluted cactus fertilizer provides enough; too much can cause soft, weak growth.
Potassium
Potassium supports sturdy growth and helps the plant cope with bright, dry conditions. A general cactus or succulent fertilizer supplies it without overfeeding.
soil
Gritty, fast-draining soil
Pencil Cactus stores water in its stems, so its roots need plenty of air and must dry quickly after watering. Use cactus soil mixed with extra pumice, perlite, or coarse grit, ideally about one-third to one-half mineral material.
pH 6,0 - 7,5
This is slightly acidic to slightly alkaline, a range most cactus mixes naturally suit. Avoid strongly acidic, peat-heavy mixes, and refresh compacted soil with gritty material when repotting.