Common Name: Pencil cactus
Water when dry
Cactus-like, leafless accent tree or table top bush
Most commonly used varieties: Euphorbia tirucalli ‘rosea’
There are over 1,600 wonderful plants in the genus of Euphorbia. A number of them make excellent interiorscape plants for sunny locations. Our Christmas favorite, the poinsettia, is a Euphorbia. The Crown of Thorns is a Euphorbia. But today, we are going to focus on a favorite one which is named E. tirucalli. Nicknames for this unique plant include pencil cactus and finger tree for the sticklike branches it grows and milk bush due to the white sap it produces. All are fitting titles for this easy-to-care-for fascinating succulent.
Euphorbia tirucalli is probably most known as a tropical, subtropical ornamental shrub that grows in semi-arid tropical climates. It is indigenous to tropical eastern and southern Africa and can grow to 30-feet-tall with a 6-foot spread in the wild, but the interiorscape plant rarely exceeds 6-feet-tall. In the southern United States, it is used as a landscape plant. In Brazil, it is often used as a hedge due to its branching capabilities and it’s tolerance to drought.
When the plant is young, the many-branched stems carry small half-inch long leaves, but these soon disappear leaving the stems smooth, cylindrical, glossy green and pencil-thick. Whenever it goes through a growth spurt the new branches will produce more of the baby leaves and shed them as the branch matures. Most of the stems stand upright, producing branches by forking into two equal-size sections at fairly frequent intervals in strong light. In lower light the intervals between branches are stretched. The main trunk and branches become woody and brownish as the plant matures, but the younger branches are green and cylindrical like so many pencils.
High light with a minimum requirement of 200 fc. These succulent Euphorbias need full sunlight all year long to flourish and continue to look vibrant indoors. To be successful in the interiorscape give pencil cactus bright light or a full sun window, as they’ll take all the light you can give them.
Water your pencil tree only when it’s completely dry. The plant will thrive in the driest atmosphere and is highly drought tolerant so water infrequently. Let the soil dry between waterings to the point of the plant starting to shrivel, then give them as much water as necessary to make the entire potting mixture moist. In their native African environment, they have evolved in a climate with occasional downpours then long periods of no rain. In the interiorscapes we need to mimic this type of feast or famine watering. Water more often during the active growing periods and in mid-fall gradually reduce the amount of water given. During the winter rest period water only enough to keep the mixture from completely drying out.
Normal room temperatures are suitable during the active growth period (spring, summer, and early fall), and they do best if given a winter rest period at 55 degrees. Can you talk your clients into that?? Because they like these cooler temperatures they will do well in building lobbies where the temperature may get cool in the winter months.
Fertilize only once or twice per year. They need very little extra food. Over the years if you have a good growing location, they will need a bigger pot. This will be partly due to getting top heavy as they grow and falling over. Repot into a larger pot with soil of a sandy mix. Any stems that happen to break off while transplanting are easy to grow as new plants. Let the wound heal overnight then plant them in a sandy mix.
Occasional mealybugs and scale. Spray with Brand X or hand wipe.