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How to Care for a Pencil Cactus

Unique, quirky, and very alluring, the pencil cactus is all of these qualities and more! Despite their rough reputation, the pencil cactus is a beautiful plant that is extremely low-maintenance.

It is the perfect stepping stone for gardeners who want to get into succulent gardening. Read on for this ultimate care guide on how to care for a pencil cactus.

pencil cactus care

Pencil Cactus Background

The Euphorbia tirucalli, otherwise known as the pencil cactus, is a unique shrub that has a hard time being boxed into any one category. The pencil cactus is native to the semi-arid tropical climates of both Asia and Africa.

Despite its name, the pencil cactus is not actually a cactus at all, but a regular succulent. While it is true that all cacti are succulents, cacti are a specific group that is defined by the round buds that form on their stems called areoles (this is where cacti grow their spines from).

Pencil cacti have neither areoles nor spines, yet they still carry the cactus name. This cactus are identifiable by their skinny, leafless stems which closely resemble pencils.

Pencil cacti are quick-growing plants and can grow to reach a height 6 feet tall when grown indoors in your home. When grown outdoors, however, this cactus can absolutely skyrocket to a height of 30 feet tall and 10 feet wide.

Older plants have brown branches, while new growth comes in green. During periods of cool weather, the branches can turn shades of orange, pink and yellow when exposed to bright sun. 

The pencil cacti does release a milky sap when cut into, which is toxic to pets and humans. It can cause severe irritation to the mouth and stomach and could cause vomiting. For this reason, if you grow this cactus plant in a home with pets and children, be sure to keep it out of reach!

Pencil Cactus Care | How to Grow Pencil Cactus

pencil cactus care

Sun & Light

Pencil cacti enjoy growing in full sunlight; try to aim giving your plant at least six hours of sunlight a day. While it does enjoy sunlight, it can also benefit from light shade, especially during hot summer afternoons.

Soil Type

Like with many other succulent plants, the pencil cactus prefers a dry, sandy soil. Select a potting mix that is specifically catered towards cacti and other succulents. Your soil pH should range from slightly acidic to neutral, around 5.5 to 6.0.

Water

Pencil cacti are very drought-tolerant plants and don’t require you to water it weekly. You should water your plant every 2 to 3 weeks during the spring and summer. In the fall and winter, only water your plant about once per month.

Please keep in mind they are very sensitive to overwatering. To avoid accidentally giving your plant too much water, wait until the soil is entirely dry before rehydrating your plant.

Fertilizer

One of the benefits of owning this plant is that it requires very little fertilizer. Use a balanced liquid fertilizer once during the springtime; this will be enough sustenance for your plant throughout the entire year.

Temperature & Humidity

The pencil cactus loves warm temperatures, so it is important to maintain a certain level of temperature to keep it healthy. Aim for a temperature range between 65° and 75° F, and do not allow the temperature to drop below 50° F.

While pencil cacti prefer dry climates with low humidity, they will not be opposed to normal household humidity conditions.

Choosing a Container & Repotting

The most important factor when selecting a container for your pencil cactus is drainage. As we’ve previously mentioned, they thrive on dry, droughty condition. Make sure to select a pot that has ample drainage holes at the bottom to allow excess moisture to pass through.

In addition, try selecting a container made from a porous material such as terra cotta or unglazed ceramic.

Pencil cacti can tolerate being pot-bound, but when you notice roots beginning to creep out from the drainage holes, then it’s time to repot. Wait until the soil has entirely dried up before transferring your cactus into a new pot, and remember to wear protective gear.

Remove the plant from its container and shake off the excess dirt from its roots. Now is a good time to check the roots for any signs of rot.

Snip off any parts of the root system that is shriveled or blackened. Repot your cactus in a slightly larger pot and fill it with fresh potting mix. Hold off on watering your newly repotted cactus for about a week.

pencil cactus care

Pruning & Maintenance

Pencil cactus pruning is fairly easy. It is recommended to prune any dead or damaged foliage on the pencil cactus. Removing these damaged branches will help encourage new growth for your plant.

When handling a pencil cactus (especially when cutting into one), remember to wear protective clothing to avoid getting the sap onto your skin.

In addition, it is always important to use sterile, clean equipment when pruning your plants. Dip your pruning shears in rubbing alcohol and wipe them off with a clean towel to prevent the spread of bacteria.

How to Propagate Your Plant

Pencil cactus can easily be propagated via stem cuttings. Follow these easy steps to turn your pencil cactus into pencil cacti!

Remember to wear gloves, goggles, and other protective clothing before handling your plant.

  1. Cut a 6 inch piece of stem from your plant. This should be healthy and green with no signs of damage.
  2. Dip the pencil cactus cutting into water in order to stop the sap from flowing out of the plant.
  3. Lay the stem out and allow the cut-end to dry out and callous over.
  4. Fill a planter with succulent potting mix and moisten it beforehand.
  5. Plant the cut-end of the stem in the potting mix and place it in a bright location. Keep the soil consistently moist as the stem tries to establish itself and grow roots.
  6. It can take roughly 4 weeks for the stem to establish and form roots. Look for signs of new growth on the stem. After the stem has shown clear signs of rooting, you can begin to care for it as you would with any other pencil cactus.

Pests

Like many other houseplants, pencil cacti are susceptible to common pests such as aphids, spider mites, and mealybugs. These three common pests are incredible detrimental to the health of your plant. While their presence is a nuisance to plant owners, they are fortunately very easy to get rid of.

Dabbing your affected plant with a cotton ball soaked in rubbing alcohol is one effective method of controlling an existing pest infestation. Insecticidal soap and neem oil also make excellent pest deterrents, as well as pest preventatives.

Pests often attack plants that are sick and stressed, so taking meticulous care of your pencil cactus is the number one prevention method. These plants become stressed when they have too much water and not enough sunlight.

Diseases

Like many drought-friendly plants, the pencil cactus is susceptible to root rot, a fungal infection of the roots, and is caused by overwatering.

When a plant such as the pencil cactus is overwatered, the soil stays wet longer. This wet soil wreaks havoc on the plants roots and can cause them to break down and rot, which in turn starts to rapidly kill the plant.

While this is a fast-killer, it can be remedied if caught early. If you suspect your plant is a victim of root rot, put on your protective gloves and remove your plant from its pot.

Rotted roots are mushy and blackened. Take a sterile pair of scissors and snip off any rotted roots. When you’re finished, repot your plant in a clean pot (with drainage holes!) and fill it with fresh soil.

FAQ

How poisonous is a pencil cactus?

A pencil cactus can be a very toxic plant due to the sap that secretes from the stems, according to The American Society for the Prevention of Cruelty to Animals (ASPCA). Contact with skin or eyes can cause severe irritation.

Don’t let this be a turn off, many gardeners have great experiences owning a pencil cactus as long as the right protection measures are taken. Always make sure to use gloves and goggles when handling your cactus, and keep it away from pets and children.

Can you touch a pencil cactus?

As mentioned above, the pencil cactus is toxic so it’s best to not touch it. If you do touch it, be sure to wear gloves to protect yourself.

Is pencil cactus good for home?

Yes, you can grow a pencil cactus indoors in your home. While they can be grown outdoors, please keep in mind that they are hardy to USDA zones 11 and 12 and survive best in hot, dry climates.

How fast do pencil cacti grow?

Unlike other cacti, the pencil cactus is a fairly fast grower and has been known to grow up to 20 inches in a single growing season.

Can I grow my Pencil Cactus cutting in water?

Yes, you can do water propagation! Allow your pencil cutting to dry out and callous first. After a few days, place the cuttings in a propagation station with water and water for roots!

The pencil cactus is a low-maintenance, easy plant to care for. Not to mention how funky it looks in your home! I highly recommend giving this quirky succulent a chance, I’m sure you’ll love it!

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Author

  • Jen

    Jen got her first plant in college from her mom and the rest, as they say, is history! She's owned hundreds of plants over the years and loves learning how to grow each one. She believes everyone needs to own at least one plant in their home and loves sharing her knowledge with others.

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