Off With Their Heads

Euphorbia, that is. Why do I keep seeing gorgeous, thick clumps of chartreuse-blooming spurge all over the place, while the clump in my garden is....well...gangly would be the kindest way to describe it.

I've never quite known how to prune these beauties, and each type has different requirements. Lower growing clumps can just be sheared down after blooming, or if they get mildewed. But how to deal with the willowy show-stopper Euphorbia characias ssp. wulfenii?

 My favorite all-time pruning book, The American Horticultural Society Pruning and Training, by Christopher Brickell (DK Publishing) to the rescue...Turns out that wulfenii stems are biennial, meaning that they develop in one year and flower the next. Here's my mistake - the stems should never be shortened; in midsummer, after the chartreuse flower domes have finished blooming, simply cut down spent stems to speed up the plant's natural cycle of renewal. Each bloomed-out stem should be cut  down to the base of the plant. This won't look as bad as it sounds, because you should leave in place all the stems that haven't yet bloomed. And don't worry, this is a vigorous plant that will regenerate quickly. 

So as soon as the flowers on this lanky wulfenii in my Whidbey garden fade, I'll cut it back to the ground. Remember, ALWAYS wear gloves when pruning any euphorbia, because the stems bleed an irritating, milky substance that can cause a nasty rash. 

 

Comments

[gardenmentor]

Cheers to you for this reminder! That milky sap is nasty. I never had a problem with it. Then, pruning my 'Red Martin' a couple seasons back, I did get a rash and felt pretty queasy after working on it. I adore Euphorbia, but always approach it with caution.

[Jan LaFollette]

I have a Euphorbia g. 'Dixter' that was damaged by last December's freeze. I've cut back the dead stuff to about six inches from the ground, maybe I need to cut shorter. It does seem to have some new shoots. Question is, when should the "blooms" be cut back or should they be cut off?

[Tracy Mehlin]

And don't wait too long to cut off the spent flowers or you'll have volunteer seedlings EVERYWHERE. Or at least I do in Ballard!
(I prune Euphorbia characias ssp. wulfenii in May)

[Lynn Warner]

Hey, this reminds me of a question I've been meaning to ask you, Valerie. I'd love to use the giant wulfenii flowers in arrangements, but can't figure out how to do it. I read up and dutifully seared the cut stem ends, but when I strip the foliage that will be below the water line, each leaf scar also bleeds! Short of spending 20 minutes prepping each stem, is there a way to use them without turning the water milky?

[kate]

May I kindly suggest wearing goggles when pruning Euphorbia? It may sound dorky but in truth, I had one of those fabled horrid encounters, as have several professional gardener friends. I didn't notice it until I felt the wretched pain a few minutes later, which was debilitating for hours. I love Euphorbia and still grow nearly a dozen types in my garden but now especially I warn people that it can be toxic to the eyes. So wear those goggles when pruning it, even if you think it won't happen to you!

[valerie Easton]

Hi Kate,
Thanks for your warning - readers take heed. I can't quite imagine wearing goggles in the garden, but you're so right that we think it won't happen to us and so don't prevent a preventable and painful accident.
Val

[valerie Easton]

Hi Lynn,
I know just what you mean - the white sap oozes from all those little slits in the stem when you strip off the foliage, and it's impossible to cauterize every one of them. I have to admit I just burn the bottom of the stem to prevent major leakage, and then stick them in the bouquet. Perhaps the sap in the water will shorten the life of the bouquet (try changing the water after a few hours when hopefully the euphorbia has stopped its oozing) but it's worth it for those giant chartreuse flowers. Also, and probably obviously - never use a glass vase.
Val