The Indian tree spurge, botanically known as Euphorbia tirucalli, is a succulent tree species that are invasive in some parts of the world but has high horticultural appeal in others.
It is easy to grow from green cuttings and requires minimal care when grown in moderate to warm climates.
In this post, we will explore what a Euphorbia Tirucalli (or Pencil Cactus Tree) is and how to care for it.
Table of Contents
What is a Euphorbia Tirucalli Pencil Tree?
Euphorbia tirucalli is an attractive, shrub-like succulent plant that can grow into a spineless, leafless tree up to 20–40 feet in height in its native environment.
Although it’s called the Pencil cactus, it isn’t a cactus at all. Rather, it is part of the large spurge (Euphorbiaceae) family.
Listed as invasive in Cuba and Hawaii, these unusual plants are believed to have originated from Africa.
Some researchers suggest the plant was introduced to Africa from India many centuries ago.
There is some evidence for this as the name “Tirucalli” is a local name found in the region of Malabar in India.
Today, it can be found in tropical Africa, as well as in tropical and subtropical parts of America (including California and Florida), Asia, the West Indies, and many Pacific islands.
Typical habitats range from woodland and grassland to brushwood and savannah.
It is also found growing along rivers; in grassy hills; and on rocky outcrops and ridges in the wild.
Can Be Grown Indoors or Outdoors
As long as conditions are suitable, Euphorbia tirucalli sticks will grow indoors or outdoors.
Often sold as the pencil cactus, it is a popular houseplant in many parts of the world, including the U.S., where there are temperate climates.
Like all Euphorbia plants, Euphorbia tirucalli grows best in full sun but will tolerate partial shade.
It makes a stunning hedge and works well when planted together with other succulents and water-wise plants like aloes.
While this plant is known to grow as tall as 40 feet in its native habitat, it typically reaches 10-16.5 feet in garden settings. Indoors and in containers outdoors, pencil cactus plants can grow up to 6 feet tall.
Outdoors, the plants will often spread to a width of 6–10 feet and 1-3 feet indoors.
Euphorbia tirucalli can grow very fast in ideal conditions. But in some areas, they grow remarkably slowly, even when grown in direct sunlight.
Other Names for Euphorbia Tirucalli
Euphorbia tirucalli has many nicknames, including Rubber Euphorbia, Pencil Cactus, Pencil tree, Finger tree, Firesticks, Sticks on Fire, Sticks of Fire, and Euphorbia tirucalli sticks.
In addition, in other regions of the world, people sometimes refer to it as the African milk bush or milkbush. However, don’t confuse it with the Euphorbia mauritanica, which is also called a Milk bush.
Toxicity
Euphorbia tirucalli secrete a toxic, white, milky sap when stems or leaves are broken.
The toxic milky sap can cause severe irritation of the skin which leads to inflammation and a burning sensation. If it gets into your eyes, it can cause temporary blindness.
So you will definitely need to be sure that small children and pets can’t access them.
Flowers
The appeal of this Euphorbia pencil tree plant is partly its lack of leaves and regular branches. Perhaps this is why it is so often called the pencil cactus.
Its stems are also pencil-like and have bright flowers that are unisexual flowers.
They are either male (stamen) or female (pistol).
Unlike a cactus plant that has quite large, colorful flowers, the pencil tree’s yellow flowers are tiny and inconspicuous. Similarly, the tiny oval leaves of the plant are easy to miss.
How to Care for a Euphorbia Tirucalli Pencil Cactus
Euphorbia tirucalli are low-maintenance plants that are very easy to take care of.
Keep them in a temperate climate, water only when needed, and they will also have minimal issues with bugs or diseases.
Like most succulents, too much water is one of the most common problems, as is too little sun.
Temperature and Climate
The pencil tree does best in dry conditions where temperatures range from about 65-75 degrees Fahrenheit during the day and no lower than 50 at night. It prefers low humidity.
But as long as the soil doesn’t get bogged with water, higher humidity levels aren’t usually a problem.
It is not winter-hardy, so if you grow it outdoors, make sure you are in USDA hardiness zone 11. However, some in zone 10 also have had success.
Light
The finger tree plant likes full sun. Ideally, it should get at least six hours of sunlight every day, even in the cooler months.
If you position your pencil cactus near a window that gets lots of bright, indirect light, it will usually do well.
Alternatively, if you can’t get your plant enough light, artificial lighting, such as a grow light, is very effective.
Watering
The pencil cactus is drought tolerant, but it’s not going to thrive if you have long periods of drought. It likes to be watered when the soil is dry.
But unlike a real cactus, it shouldn’t be left growing in totally dry soil for any length of time.
At the same time, this plant shouldn’t be left with its roots sitting in wet soil because the roots can rot.
It is essential to ensure that a plant growing in a container has adequate drainage holes to avoid root rot.
They do particularly well when planted in a good quality cactus potting mix or some other well-draining soil.
Soil
Pencil trees will thrive in sandy soil that drains well. When growing in-ground outdoors, ensure you have well-drained soil.
You can make the soil drain well by adding some soil amendments like coarse sand or perlite to the garden.
Alternatively, if you decide to grow a small pencil tree indoors, you can opt to buy pre-mixed succulent soil.
Fertilizer
Euphorbia tirucalli stick plants don’t usually need fertilizer to grow. However, if you see that your plant is not doing well, you can give it a boost with a balanced liquid fertilizer in spring.
A slow-release fertilizer is ideal, as it will provide nutrients over an extended period of time.
Alternatively, you can use a liquid fertilizer every two weeks. Be sure to water the plant thoroughly after applying fertilizer.
How we usually go about fertilizer is that we use self-dissolving fertilizer pellets.
How it works is that it slowly dissolves into the soil on its own, so there’s no worry about over-fertilizing.
Pests and Diseases
There are no particular pest or disease problems that attack Euphorbia tirucalli sticks, but it’s best to keep a check on common bugs like aphids, nematodes, spider mites, and mealybugs.
Fungal and bacterial conditions can be problematic from time to time as they can cause root rot.
Root rot is a fungus that affects the root system of the plant. It causes the roots to rot and decay, which can lead to the death of the plant.
Signs of root rot include wilting plants, yellowing leaves, and stunted growth. Root rot can be treated with fungicide, but it is important to catch it early before it has a chance to kill the plant.
Repotting
If your pencil cactus has been in its current pot for more than two years, you may want to consider whether it is time to repot it.
Use a pot that is at least 2 inches larger than the current pot. Be careful not to damage the roots when repotting.
Fill the pot with cactus soil, making sure to pack it down well. Water the plant well and place it in a sunny spot.
The soil should be allowed to dry completely between waterings. If you see any signs of mildew or fungus, treat them with a fungicide.
You can repot your pencil cactus plants easily if they outgrow the pot. Remove it gently and trim any dead or shriveled roots. Pot in some fresh cactus potting mix.
Propagation
Pencil tree plants are particularly easy to propagate from cuttings, but be sure to wear rubber gloves to make sure the sap doesn’t get on your skin.
Green cuttings from branches should be about six inches long.
Dip the cut end into water and then let it dry for about a week before sticking it directly into the soil in your garden or the pot.
Pruning
When caring for a pencil cactus plant, it is important to remember that they have delicate finger-like branches. If you grow your pencil cactus plant in a pot, you may want to prune its finger-like branches.
However, using shears to prune the plant can be dangerous because you may accidentally cut off more than needed. It is best to use your fingers to carefully pinch off the branch instead.
If you do need to use shears, make sure to cut away from the stem and avoid coming into contact with the milky sap.
Ideally, when you prune a pencil cactus, you can use the cutting to propagate new plants.
FAQ
How poisonous is Euphorbia Tirucalli?
Euphorbia tirucalli is highly toxic. If exposed to skin, it is extremely irritating, causes burning sensations, and can cause mucous. If the milky sap enters the eyes, it can possibly blind the person. If swallowed, call emergency services as soon as possible as it will burn the inside of the mouth. Keep this plant away from small children!
How tall does Euphorbia Tirucalli grow?
Euphorbia tirucalli, commonly known as Indian Tree Spurge or Pencil Tree, can grow as tall as 20 to 40 feet tall and up to 10 feet wide. When planted outdoors, these are massive cactus plants. However, they can be trimmed down and grown inside in a pot.
How often should I water my Pencil Cactus?
Euphorbias tirucalli, or pencil tree cactus, does not require a lot of water. The rule of thumb is to only water the plant when the top portion of the soil is dry. You can easily stick your finger into the soil to find out. Equally important is to have your plant in a container that has drainage holes at the bottom.
Does Pencil Tree Cactus need full sun?
Euphorbias tirucalli, or pencil tree cactus, like other euphorbia plants, likes direct sunlight. These plants should get anywhere from 4 to 6 hours of direct sun each day. If it doesn’t, you will notice your plant starting to fade.
Conclusion
The pencil cactus is easy to grow and maintain. While it’s a stem succulent rather than a cactus, it thrives in similar conditions with warm temperatures, lots of sunlight, and minimal watering.
Other Euphorbia Plants
Euphorbia plants make excellent indoor and outdoor plants for those who want easy-to-maintenance plants that are drought-tolerant. Some Euphoria varieties bloom flowers that are very eye-catching and brighten up your front yard’s curb appeal. Below are some sample of other types of Euphobia plants.
Euphorbia Milii: Well known as the “Crown of Thorns,” it is believed to have originated in the Middle East. According to Christianity, Jesus Christ wore a crown of thorns crafted from this plant. Consequently, some call it the Christ Plant or Christ Thorn. It blooms with vivid and dark red flowers that can be grown both indoors and outdoors in warm regions.
Euphorbia Trigona: African Milk Tree, Cathedral Cactus, and Candelabra Cactus are some of the names given to this species. It’s a plant that grows vertically and doesn’t extend much wider than its base, making it ideal for landscaping in warm areas.
Euphorbia Leucodendron: The Euphorbia leucodendron, commonly known as the Cat Tails Euphorbia Plant, is a succulent shrub with spineless branches that, in perfect conditions, can develop into a small tree. It is a wonderful plant for landscaping. Its natural habitat is the subtropical region of Madagascar, where it can reach heights in excess of 10 feet.
References
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.