Euphorbia grandicornis

cow’s horn euphorbia
Columnar euphorbia with crumpled zig-zag form and ornate thorns is a living sculpture. Freely branches into shrubby form. Great in pots with good drainage.
Euphorbia grandicornisEuphorbia grandicornis
height 3–6ft
width 3–6ft
tolerates Drought, Deer , Gophers, Heat, Pots, Rooftops, Neglect, Wind
water
needs		 Low – Moderate
water
info		 Columnar euphorbias are very drought tolerant but will grow faster if they receive some summer water, usually every couple weeks to a month once established (let the plant dry out between waterings). If you aren’t getting summer growth you may be underwatering. These plants prefer a dry winter; outdoors in central California, they won’t need supplemental winter water once established.
hardy
to		 28F
exposure Part Shade – Full Sun
indoor
outdoor		 Outdoor
drainage In Ground: Cactus Mix, In Pots: Cactus Mix
fertilizing All Purpose
origin E Africa
california
native		 No
sunset
zones		 13, 16, 21–H2

Sunset Zones Map

Outdoor Exposure Guide

Growing Notes

Columnar euphorbias can get surprisingly large, so be sure to note the size, and place your plant accordingly.
They respond well to pruning. They will look scarred for a while, but then will push new growth wherever they are pruned, often giving you several new growth points. Take care when pruning, as euphorbias have toxic sap that can cause a skin rash or damage to the eyes (make sure to rinse repeatedly with water if sap gets anywhere near your eyes).
They like a warm sunny exposure but do surprisingly well in shady areas as long as they aren’t given extra water during winter.
As columnar euphorbias grow they will transition from colorful and smooth new growth to dull, brown and rough older growth. This is called corking, and it is totally natural. Think of this like an oak tree where the new shoots are shiny and green, but then eventually you get a trunk covered in rough dull bark.
Soft dark brown spots on Euphorbia are usually a sign of rot. Carve these spots out with a sterile knife immediately (carve all the way back to healthy-looking tissue). Rot usually results from overwatering, but it can also be caused by drastic under-watering. Occasionally this will start at the base of the plant, which means the roots have rotted. If you’d like to save the plant you’ll need to remove the top above the rotten base, let the top sit for two weeks in a shady spot, and then replant in very sharp-draining soil. Place the cutting in a warm spot to re-root, preferably not in harsh sun.