May 30, 2006

Crown of thorns cactus

Euphorbia milliiI call this the plant only a man could love. And the fellow who originally gave me a piece of his definitely loved it. He didn't believe in pruning and it had grown into this great monstrous thing that looked like an escapee from a horror movie, with drooping, spiny branches on a plant three or four feet high and almost as wide. I would take guests around to gawk at it on his front porch in the summer, and their jaws inevitably dropped. He had grown his from a cutting his now deceased mother had given him, she in turn having received it from a neighbour who'd brought it over to North America from Vienna decades ago, so this is a plant with a lot of history.

So meet Euphorbia milii, the crown of thorns cactus. Despite the name, it was not found in Palestine two millenia ago, being a native of Madagascar. As a member of the vast and varied Euphorbia genus, it has the characteristic white sap that can irritate your skin. Seeing as you can't get up close and personal with this fellow without heavy gloves on, that rarely causes problems.

To take a cutting, I get a good grip on one of the sturdy thorns and nip off a branch with pruners or sturdy scissors. After I rinse away the white latex with water, I leave the cutting to dry for at least a couple of days so the end won't rot. Then I just stick it in potting soil (carefully!) and keep it a little on the damp side until new growth appears. It's an easy-care plant and while it prefers normal care, will get by quite nicely with a little neglect. Given enough sun and a bit of fertilizer it will produce little orangey red blooms, but for me, they are not the highlight. There are a lot of newer cultivars available with showier, more numerous blooms for which it might be worth making an effort to stimulate bloom, but I've never tried very hard.

The crown of thorns cactus will react to stress (especially when brought back inside in the autumn) by dropping some or all of its leaves, but it recovers quickly and the new growth is quite attractive, particularly if the plant has been pruned to a nice shape. I haven't been too successful in shaping this one, but in the past I've had some beauties. I tend to give them away when they get large and start over with fresh cuttings.

Mine is now occupying a strategic position in my flower bed that used to serve as a corridor for cats. "Used to" is the operative term. Felines recognize someone with larger claws and keep a respectful distance.


jdlahunt said...

hi,glad i found your blog,i just recently bought a crown of thorns by mail and it was shipped to me bareroot,i have potted the plant but it looks sick and not healthy,the leaves are turning yellow ,drooping and drying up."help!!"i dont know anything about this plant but want to keep it alive and growing.should i water it now .any info will be greatful.thanks

Anonymous said...


I'm from Sydney Australia and i have a passion for euphorbia milii's. I noticed that in your picture you posted that the plant was placed indoors. I just wanted to suggest that they grow and flower more often and brighter in the sun. Around 70% sunlight and 30% shade. And to remember to not water it to often as it causes the roots to rot.
I hope i helped. Thanks

RAH said...

"Despite the name, it was not found in Palestine two millenia ago, being a native of Madagascar."

You forgot to mention, although it's implied by saying they're from Madagascar, that despite the name the crown of thorns isn't a cactus either. Splitting hairs I suppose but cactus are only native to the Americas. Euphorbias are often, of course, mistaken for cacti.

--Just a nitpicker cruising the net.

P.S. Like the blog though

Janet said...

Rah, you are absolutely right. I just limit my myth-debunking to one per post... ;o)

When a plant has a misleading popular name, I tend to use another popular name if it's available - I call evening primrose "sundrops", for example. Are there any commonly used names for Euphorbia milii besides Crown of thorns cactus?

Anonymous said...

I have a cutting and wasnt sure how to propigate it so I went to the garden center and she said to
put it in water (change the water daily) till it roots then plant it in dirt. I loved it so much I ended up buying on at the garden center in case the cutting doesnt make it.

My neighbor in Florida has one outside in a pot and its beautiful.

Do you think the water will rot it before the cutting gets a root?
Thanks. janet

Janet said...

I have no idea, Anonymous (April 30). That is pretty well the opposite of the method I was told to use and which has worked every time for me (which is in the post).

I'm sorry I was asleep at the wheel, so I'll answer the older comments now. JDL, as you've probably learned, this plant reacts to stress by dropping leaves. It does this to me almost every year when I bring it in for the winter. The sudden change in conditions scares it. It always recovers.

Anonymous July 6, I'm in Canada. In the winter, the plant comes in. Trust me, they don't grow better outside in a Canadian winter.

Anonymous said...

I had a Crown of Thorns that was destroyed in a fire two years ago. I have looked for two years to find another and just did so this past weekend. I was searching for information on the www and found your blog. The Crown of Thorns is a stiking plant and I found it in a small (starter) size at Home Depot in three colors. I am really excited. Can anyone tell me how low the temperature can go before I have to bring it indoors?

Janet said...

Laura, it's a tropical plant and will not tolerate freezing. Other than that, I can't tell you for sure. I would suspect that under about 45F (7C), you're taking a risk.

I prefer to bring it in before the nights get too nippy so that it won't drop all its leaves on me.

Betty said...

Help! I have a huge (about 35 years-old) crown of thorns that spent the summer in the garden and is now in serious trouble. The spines are soft and the branches are hollow and black inside.

What can I do? There is some new growth at the bottom which I can probably root, but is the main plant a goner?

Thanks very much.

Janet said...

Betty, I'm not an expert on plant diseases by any means, but I suspect the plant is doomed. If it were mine, I'd remove a couple of healthy shoots and root them and keep them far away from the mother plant. You can try to save it, but I wouldn't get too hopeful if I were you.

Michele said...

Hi Janet,
I live in Fort Pierce, FL and have three magnificent crowns of thorns growing close together in front of my place. They are 4' tall and were in full bloom... until temps went below freezing here this week. I didn't think of covering them because last year, temps went down to 30F for a couple of nights and this had not bothered them. But this time, with temps down to 28F, all of the leaves and flowers froze on one of the plants. Incredibly, the two others still have intact leaves & flowers. With temps going to 27F tonight, I will cover them of course and I'm thinking of putting a heater under the cover. My question is, do you think that this type of plant has a chance to survive after losing all of its leaves to frost? I cut off all the the frozen leaves, was this the right thing to do?
Many thanks, Michele

Janet Ursel said...

Crown of thorns drop their leaves in response to stress anyway, so losing leaves and flowers shouldn't cause any longterm problems, as long as the stems are intact. My guess is that your plants will recover, although they might lose the extremities of branches too.

I don't know how much freezing they can take before there's more serious damage though. Covering them definitely sounds like a good idea. You might want to take a few cuttings and bring them inside, just in case.

Gerri said...

This pic is exactly like my plant. Thank you so much for your helpful hints. I bought my crown of thorns at my church bazaar last year and it has been blooming since. I love it! Now I know how to clip it and make new plantings. What about trimming in the winter? Is it not a good idea? Thank you so much.

Janet Ursel said...

Sorry for the delay, Gerri. As far as I know, it doesn't matter which season you trim it in.

Deb said...

I have inherited the crown of thorns after my dad passed away. It was long and lanky so I trimmed it back. How do I prevent it from getting long again? I was hoping to keep it shrub like if that is at all possible

Janet Ursel said...

Deb, you can prune this plant quite brutally without worrying too much. Whenever I can't seem to get the shape of mine under control, I start a new one. LOL. Not exactly expert advice, but at least it works.

Gerri said...

Mine was getting long and lanky. I had bought it at my church social. I looked on line and followed the directions. I just cut off the long shafts and just re-planted the cut off portion right back in the ground. My plant is just beautiful and getting wider now. I noticed that it is growing like a weed again, so I will do the same thing. Not all the shoots I cut propagated, so don't be dismayed. Good luck.