Botanical Name — Euphorbia tirucalli
Common Name — Pencil cactus, Milk bush, Pencil tree, Indian spurge tree
Plant Family — Euphorbiaceae
Euphorbia tirucalli is a tree that grows in the subtropical climate. It is widely distributed in Africa, and found most commonly in northeastern, central, and southern Africa as well as parts of India. Nicknamed the pencil cactus, this plant is actually not a cactus at all, but instead a succulent member of the Spurge family. This plant produces a poisonous latex that can be converted to gasoline, and at one point chemists proposed the exploitation of the plant for gasoline production, estimating the harvesting potential of 10 to 50 barrels per acre of crop.
- Euphorbia plants require at least 5 - 8 hours of full sun, daily. Late afternoon sun is ideal as hot, afternoon sun can be quite harsh and cause branches to burn.
- Pencil trees prefer warm temperatures between 65 - 70 ºF. Native to subtropical climates, they are tolerant of some humidity but will thrive in arid climates.
- These plants are cold hardy to 25 ºF. Plants should be moved indoors during the peak of winter.
- Water pencil cactus sparingly. Water soil thoroughly, allowing it to dry completely in between waterings.
- Euphorbia tirucalli require a sharply-drained, gritty mixture. Use cacti or succulent soil, or amend potting soil with sand or pumice up to 50% to improve drainage.
- E. tirucalli produce small, inconspicuous yellow flowers and the tips of branchelets in stalk-less clusters. Flowering typically occurs in the summer though these plants rarely flower when cultivated indoors.
- Fertilization is not necessary. If you want to give your plants a boost, you can fertilize mature plants with a balanced 20-20-20 fertilizer diluted to a quarter strength once a week. Use a fertilizer with a lower nitrogen rating for younger plants. Only fertilize during the active growing season, spring and summer.
- Pencil trees are easily propagated by stem cuttings. Try to take a cutting that has at least three branch segments. Dip the cutting in cold water to stop sap from oozing, then allow the cutting to sit out and callous for a few days before placing it in moist sand or cacti mix. Place the cutting in a bright spot out of direct sun while it is establishing itself.
- Always wear gloves when handling this plant. The sap is highly irritant to skin and is easily released if the dermis of the plant is broken at all.
- These plants are quite resistant to pests and diseases. Root rot can become a problem if the plant is overwatered and will quickly kill the plant. Plants weakened by root rot are more susceptible to common pests, so always err on the side of underwatering.
Maintenance (pruning, legginess, repotting)
- Pencil trees are super hardy and require little to no maintenance. These pots have very shallow root systems and prefer to be root bound. These plants should only be repotted once every 3 to 4 years. These plants can be potted in shallow planters, deep, large planters increase the risk or root rot, as they can take longer to dry out.
- Always wear gloves when handling this plant as sap is highly toxic and irritant to skin.
- All parts of the plant contain a poisonous, white latex that is extremely toxic to pets and humans if ingested and highly irritant if contacted with skin. Take great care when handling this plant and keep out of reach of children and pets.