You Won’t Believe How Easy It Is To Grow Euphorbia grandicornis (Cow Horn Cactus)

Imagine a quirky, spiky plant that looks like it came straight out of a Dr. Seuss book! That’s the Euphorbia grandicornis, better known as the Cow Horn Cactus. With its wild appearance and easy care, this plant is a must-have for any houseplant lover or gardener. Keep reading to discover just how simple it is to grow this unique succulent.

euphorbia grandicornis

About the Cow Horn Cactus

The Cow Horn Cactus isn’t actually a cactus at all – it’s a type of euphorbia, a family of plants with thick, fleshy stems. It grows in a shrubby form with a few upright stems that can reach up to 6-7 feet tall! These stems are covered in pairs of large, whitish-brown spines that resemble…you guessed it, cow horns! In spring, clusters of tiny yellow flowers bloom adding a pop of color.

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Euphorbia grandicornis Care Guide


These plants thrive in full sun, needing at least 6 hours of direct sunlight each day. Too much hot afternoon sun can cause burns though, so provide some shade during the peak heat. When growing indoors, place it in a sunny, south-facing window or use a grow light designed for succulents.


The Cow Horn Cactus is drought-tolerant, only needing water when the top 2 inches of soil are completely dry – about once a week in spring through fall. Make sure to water thoroughly then let it drain completely. In winter when dormant, water very sparingly, maybe once a month if it starts to shrivel.


cow horn cactus

Like other succulents, this plant wants a gritty, very well-draining potting mix. Use a commercial cactus/succulent mix or make your own by combining potting soil with an equal amount of coarse sand or perlite.


Feed your plant a weak liquid fertilizer made for cacti or succulents during the spring and summer growing seasons. Avoid fertilizing in winter.

Temperature and Humidity

Daytime temperatures of 70-90°F and nights around 55-65°F are ideal. It can handle some dryness indoors but prefers 50% humidity year-round.

euphorbia grandicornis

Pests and Diseases

The biggest pests to watch for are spider mites and mealybugs. Act quickly if you see signs of these sap-sucking insects.

Euphorbia grandicornis Propagation Guide

Taking stem cuttings is by far the easiest way to propagate the Cow Horn Cactus. Seeds can be tricky to germinate and grow slowly.

  1. Using a clean, sharp knife, cut off a stem segment right below a pair of spines. Aim for cuttings 3-5 inches long.
  2. Allow the cutting to dry for a few days until the cut surface has calloused over. This prevents rotting.
  3. Once calloused, simply stick the cut end into a well-draining potting mix. You can dip it in rooting hormone first if desired.
  4. Place the cutting in a warm spot with bright, indirect light. Keep the soil lightly moist.
  5. Within 4-8 weeks, you should see new growth at the base, indicating roots have formed! Then care for this new plant just like the parent.