My sister Glenda called and invited me to a homemade strawberry and blueberry pudding feast on Sunday, and being a great cook, I couldn't pass up the opportunity.
On my way into the house, I stopped to take a look at a plant she calls a “crown of thorns,” which is in a large pot on her porch. After Glenda introduced me to her plants a few years ago, I bought one myself, so I like to check on its growth periodically.
Well, mine died the first winter, either from cold or lack of water. I'm not sure which. Glenda has kept her crown of thorns alive and beautiful for about five years, so I consider her an expert on the subject. I grow it as an outdoor plant on my balcony in summer and as a houseplant inside in winter. So what is this thorny plant with pretty red flowers that look like they might hurt you if you touch them?
Crown of thorns is Euphorbia millii or E. millii. Euphorbia is a large genus of smooth, thorny shrubs and cactus-like succulents that grow from 4 inches to 20 feet tall in the Euphorbiaceae family.
There are over 1,600 species of Euphorbia, including poinsettia, castor bean, and cassava. Common names include Christ plant, Christ thorn, crown of thorns, or crown of thorns. It is popular as an ornamental plant and is grown as a garden shrub in warmer climates.
The North Carolina Department of Education describes the plant as a deciduous perennial herbaceous shrub with bright green leaves and greenish flowers that are housed in long-lasting bright red or yellow bracts.
The plant is loosely shaped, spiny, and irregularly shaped with thick black thorns. Due to its historical presence in the Middle East, it is believed that the stems of this plant were used in Christ's crown of thorns, which is where the common name comes from.
The red bracts of the flower represent blood. In its native country of Madagascar, the plant grows to a height of 5-6 feet, but in the United States it typically grows to a height of 3 feet, or 2 feet when grown as a houseplant.
Crown of Thorn grows best in full sun with some mid-afternoon shade. It needs well-drained, dry soil with low humidity. It does not like wet or cold soil or temperatures below 35 degrees.
Although it looks dangerous, if you're brave enough, you can propagate it by taking cuttings from the tips. First, make sure you wear thick gloves. Second, be careful when taking cuttings, as the white latex liquid inside the thorns can cause a mild toxic reaction if it comes into contact with your skin or eyes.
Allow the sap to dry, then place the cuttings in a growing medium such as Pro-mix25, which my gardener friend Lisa Todd says is a peat-based mixture mixed with perlite and partially composted pine bark.
It produces pairs of 2, 4 or 6 dainty red flowers at the ends of grey stalks. The stems are easily identifiable by their long thorns, which can be dangerous to unwary gardeners, children and pets. When the flowers begin to fall off before the plant goes dormant in winter, it can get a bit sticky and messy.
This plant has no known serious pests or diseases, but indoor plants are known to be susceptible to leaf spots, stem and root rot, scale insects, mealybugs, thrips and mites.
I spoke with Glenda and she told me that she's had to repot this bramble twice over the years that she's had it grow. As an aside, she told me that although she loves the plant, she probably won't repot it again, given its size.
Now, five years later, it's 32″ tall and 28″ wide. I only water it when the soil feels dry. In the spring and summer, I keep it on the edge of a sunny porch or on a sunnier deck.
In the fall and winter, she brings it indoors and places it in front of a sunny window because if it doesn't get enough sun, the pretty red flowers turn pink. Crown of thorns is not an easy plant to find, but I will look for it and give it another try.
If you have any other gardening questions, please contact a Master Gardener Extension volunteer at the UGA Extension Carroll County office at the Carroll County Agricultural Center, 900 Newnan Road, Carrollton, at 770-836-8546 or by email at ccmg@uga.e .
