How to Prune a Pencil Cactus

Pencil cactus (Euphorbia tirucalli), also known as milk bush and pencil tree, grows in U.S. Department of Agriculture plant hardiness zones 10b through 11, and is commonly grown as a houseplant in cooler climates. Pencil cactus displays slender, pencil-like stems with few, inconspicuous leaves, flowers and petal-like bracts. The pencil cactus can grow up to 30 feet tall outdoors, though growth is generally slow, and remains much smaller when grown in containers. Pruning is rarely required, but you might need to head back some of the branches if it outgrows its space.


Clean and disinfect the bypass pruner blades with a solution of diluted bleach, using one part bleach to nine parts water. Reserve the bleach solution until after you finish pruning the pencil cactus.


Wear a pair of thick rubber gloves when pruning pencil cactus because the stems contain toxic, milky latex that can cause blistering and dermal rashes if it comes in contact with skin. The long, thick gloves often used when washing dishes work well because they provide protection to your forearms as well as your hands. Long sleeves, pants, covered shoes and goggles should also be worn, especially when pruning large specimens with more latex in the stems; the sap can cause severe eye irritation.


Cut any broken or dead stems back to the nearest healthy branch union, cutting just outside the joint so you don't leave a stub. This can be done at any time throughout the year.


Cut the plant back to the desired height and width if it becomes too large for its container or space in the garden. Cut back to a branch union to conceal the cut. You can also cut branches to stimulate new branching and give the plant more of a bush form.


Spray the cuts with water immediately after making a cut to stop the latex from oozing out of the stems.


Clean the pruners in the reserved bleach solution to remove all the toxic white latex, then dispose of the solution. This is important because you don't want to pick up your bypass pruners without gloves later and get a rash or blister.

Things You Will Need

  • Bypass pruners
  • Chlorine bleach
  • Rubber gloves
  • Protective clothing
  • Spray bottle


  • Wash hands thoroughly after pruning pencil cactus, even if you wear gloves.
  • To propagate, allow the cut end to callous, then root the cut end in sand or sterile perlite.
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