Pencil Cactus (aka Euphorbia tirucalli or ET) is not a cactus. It is a rugged succulent plant that can grow to be over thirty feet high in the wild. However, it can also be kept to a more moderate height of 6-8 feet when kept as a houseplant.
These attractive and interesting plants take on a great deal of character as they age, and older plants develop thick inner branches with rough, gray, highly textured bark. The foliage is an attractive shade of green throughout most of the year and transitions to yellow, orange or red during the cooler months.
In this article, we will share information on growing, caring for and appreciating this fascinating plant. Read on to learn more.
Pencil Plant Care
Care varies somewhat depending on whether you want to keep your pencil plant indoors or outdoors.
Pencil Cactus Indoor Care
Light: This plant enjoys the full sun making it an excellent choice for a very sunny window setting. Rotate the plant periodically for balanced growth and even color development during the cooler months.
Water: The house plant should be watered weekly during the growing season. Take care to provide well-drained soil and plenty of drainage holes in the container to avoid root rot. Cut back to monthly watering during the cooler months.
Temperature: Although this plant can tolerate temperatures from 25-100 degrees Fahrenheit, it prefers temperatures ranging from 50-70 degrees Fahrenheit. Ideal pencil cactus temperature range is 65ºF – 70ºF, so it does well year-round indoors at normal household temperatures.
Soil: Use a high quality, well-drained cactus or succulent mix with a pH of about 6.0.
Fertilizer: You may feed your finger plant seasonally with a controlled-release fertilizer or use a weak liquid solution on a weekly basis. Mature plants do well with a 20-20-20 fertilizer. Younger plants do better with a lower nitrogen rating. Some people do not fertilize pencil plant at all.
Pencil Cactus Outdoor Care
Light: Outdoors, pencil cactus does well with either partial or full sun. It’s best to place the plant so it gets sun exposure on all sides for balanced growth and coloration.
Water: It’s better to give too little water than too much. Outdoors water deeply about once a month during the growing season and once every couple of months during cool weather. These drought tolerant plants may do well with only rainwater.
Soil: When planting outdoors, it’s a good idea to add some light, finished compost and/or some loam to your soil to improve its aeration and draining capabilities.
Fertilizer: If you keep a worm composting bin, you will find that a layer of worm compost or worm castings spread over the top of the soil annually provides all the nourishment your ET needs.
Pests: With their toxic sap, these plants are fairly pest resistant. Common succulent pests, such as plant mites, colonies of mealybugs, cactus scale and aphids may be a problem for over watered and weakened plants, but for the most part, Euphorbia tirucalli is pest free. [source]
Transplanting, Repotting & Propagation
If you plan on transplanting a milk bush, do it while the plant is still small. Moving a tall pencil cactus is difficult due to weight and breaking branches.
Remember, you want to limit exposure to the toxic, irritating sap. If you want to relocate an outdoor pencil tree make sure to wear goggles, gloves, long pants and a long-sleeved shirt. Change clothes and wash up as soon as you are done.
Repot Your Pencil Tree Frequently
These plants grow rapidly, and you may need to repot annually or at least every couple of years. It’s best to allow the soil surrounding any succulent to dry before repotting.
Remove the plant from its pot and knock away or shake off all the dry soil. If the roots become damaged, treat affected areas with a fungicide to prevent root rot.
Related Reading: Another Unusual Cactus Cephalocereus senilis aka Old Man Cactus Plant
Put the plant into a new container and add a light, well-draining soil mixture. Standard cactus or succulent mix works well. You may wish to add some light, finished compost to provide nourishment and relieve you of the task of fertilizing.
Don’t water the newly potted succulent for about a week. This will encourage root growth and discourage root rot.
Pencil Plant Propagation Is Easy
There’s not much need to relocate these plants because these cactus plants are so easy to propagate from cuttings. Remember to protect yourself from the sap when taking cuttings. Dip the cut end in cold, fresh water to stop the sap flowing.
Leave the cutting in the open air for a week or so to form a callous. Pop it into a pot of moist sand, succulent mix or cactus mix. You’ll probably see growth within a week to ten days.
Is Pencil Cactus Poisonous?
When you picture the Pencil Cactus in your mind’s eye, you are unlikely to realize that it is closely related to such diverse plants as African candelabra cactus, poinsettias, crown of thorns, Mediterranean spurge and flowering spurge. One thing these plants all have in common is irritating/toxic white sap.
All members of the Euphorbia family contain this poisonous, irritating sap. That of the pencil cactus is the most powerful of them all. That’s why it is so important to protect your eyes, hands and skin when pruning.
Avoid casual contact with the plant. Place your “sticks on fire” plant carefully so people are not constantly brushing up against it and breaking its branches.
You should especially keep kids and pets away.
What You Need To Know About Pruning Euphorbia tirucalli
Euphorbia is used as a hedge plant in Africa due to its dense growing habit. Indoor plants may need trimming and tidying up to control size and improve appearance.
Outdoor plants able to grow freely will not need as much pruning. It’s a good idea to thin the stems from time-to-time to allow light and air circulation. Indoors or outdoors, be sure to prune in a balanced way so the plant does not become top-heavy causing landscaping plants to break and fall and potted plants to tumble over.
Always prune stems back to the main trunk. Don’t chop them off in the middle as this produces an ugly appearance and cause the plant to branch out.
Drop cut branches into a tub of cold water to control the sap spillage. Wipe sap off the main trunk with a cool, damp cloth to help stop its flow and to prevent accidentally coming in contact with it as you work.
When pruning, take great care not to get the sap in your eyes or on your face. Topical exposure to the diterpene esters found in the sap can cause numbness, tingling and burning sensations.
Getting the sap in your eyes can cause corneal damage and may result in temporary blindness. [source]
If you get sap on your skin or in your eyes, flush with copious amounts of fresh water immediately.
When washing milk bush sap from the skin, wash gently with clean, running water. Don’t scrub or rub.
When flushing the eye, use clean, running water and continue flushing for about twenty minutes to be sure every trace is removed.
In either case, if this does not relieve your symptoms completely, seek medical assistance. [source]
What To Do In Case Of Accidental Ingestion
If you have children or pets, be aware of the symptoms to watch for in the event of accidental ingestion.
- Burning in and around the mouth
- Irregular heartbeat
- Stomach cramps
- Skin Rashes
The type of symptoms present and their severity depend upon the amount of the plant that is ingested. In case of ingestion, remove any remnants of the plant from the child or pet’s mouth and rinse with clean water.
If the victim is a child, follow up by calling your pediatrician or the Poison Control Center at 1-800-222-1222 immediately. Follow instructions carefully, and remember to take a sample of the plant along with you if you are instructed to go to the emergency room.
If your child is experiencing high temperature, shortness of breath, seizures and/or unconsciousness, don’t waste time. Call 911. [source]
The latex sap found in Euphorbia is also toxic to cats, dogs, and equines (horses, donkeys and mules). [source]
If you find your cat or dog is vomiting and/or experiencing irritation in and around the mouth, you may suspect pencil cactus poisoning.
With equines, you would see oral irritation, trouble swallowing and symptoms of pain in the stomach and scouring, but these animals cannot regurgitate.
If you think your pet has consumed Euphorbia tirucalli, call your veterinarian or the ASPCA poison hotline (888-426-4435) for advice. If you are instructed to bring your pet in to your vet’s office or to an emergency clinic, be sure to take along a sample of the plant. [source]
Is It Safe To Keep Pencil Cactus At All?
Dire as all this sounds, you needn’t go overboard with alarm.
There are lots of potentially poisonous plants, but luckily most of them taste terrible and accidental ingestion is rare.
If you place your pencil cactus plant sensibly, so people and pets are not constantly knocking up against it, you are unlikely to have problems with accidental skin exposure.
Just remember to be very careful when pruning and wear eye protection. Pencil cactus doesn’t just drip sap. It has been known to squirt or spray it! [source]
Even The Worst Gardener Can Grow Happy, Healthy Pencil Cactus
If you have a brightly lit, warm, dry space, you can expect your Pencil Tree to quickly and easily grow. These unique looking plants make attractive and unusual specimen plants in the garden, solarium or greenhouse. They pair well with a beautiful container to dress things up.
It’s possible to control your plant’s size with regular pruning, but be sure to follow all the safety precautions we outlined here. Remember to place your plant where it can be seen but not bumped!
If you are a forgetful gardener or one who tends to be absent frequently, this drought loving plant may be just the right choice for your sunny window, deck or rock garden. Pencil plants grow easily and demand so little. If you have lots of light and a little water, you and your pencil cactus will get along just fine.