Tree Talk: ‘From the merry old land of Oz’

If only Hollywood had consulted a gardener to design the sets for “The Wizard of Oz.” They’d have gotten it right.

Remember that iconic moment with Dorothy, the Cowardly Lion, the Tin Man, the Scarecrow and Toto standing on the Yellow Brick Road, looking at the Emerald City in the distance? Think of how that shot would have really popped if the road had been flanked with the chartreuse bloom stalks you see in the photograph: euphorbia characias wulfenii, sometimes sold as euphorbia veneta.
All last month and well into May, these Ozian flowers stand munchkin tall in clumps, often over 4 feet high and as wide, their domed blossom cylinders on stems lined with narrow celadon leaves. So spectacular and easy to grow is this startling and statuesque plant that it has been in cultivation in the Pacific Northwest for likely a century or longer.
There are more than 1,600 members of this genus. A number, like E.c. wulfenii, are native to the Mediterranean, many referred to as spurge or milkweed. All are easy to grow given rich, quick-draining soil and ample sunlight.

There are some surprises in this genus. Houseplant lovers may have grown African milk tree, euphorbia trigona or Crown of Thorns, euphorbia milii or E. splendens. The old-fashioned self-sowing annual, Snow-On-The-Mountain, native to central North America, is euphorbia marginata. If you ever bought gopher plant or mole plant and used it to discourage the ornery critters who give the plant its common name, you were growing euphorbia lathyris.

If last month, you noticed mahogany shoots emerging in perimeter plantings with unexpected orange blossom clusters starting to unfold, you were looking at the much loved, but much underused euphorbia griffithii “Fireglow.” In time, this dazzler forms massive clumps with long-lasting fiery orange flower heads. When the foliage emerges, it combines powerfully with solid yellow or orange tulips or underplanted with cobalt blue grape hyacinths. Most surprising of all, the poinsettia that graces nearly every home in the winter holiday season is a euphorbia — euphorbia pulcherrima.
When the blooms of euphorbia characias wulfenii lose their luster and start to turn to seed in summer, it’s time to cut the blooming stalks back to the ground. Carefully isolate each flowering stem, snip if off and compost it, but don’t remove the lower, new growth that will surround each of the old bloom stems. With all the old blooms gone, you’ll be left with a handsome mound of new growth, bluish green, to enliven your fall and winter garden and have the stems upon which next year’s flowers will emerge.
Now for the part of this story that would make the Wicked Witch of the West cackle with diabolical glee. The broken stems of many euphorbias ooze a milky sap, ergo the common name milkweed.

To some, the sap causes a severe dermatitis, much like contact with poison ivy or poison oak. Long sleeves and garden gloves are a prudent uniform when cutting the old flower heads to the ground. Euphorbias should not be planted at the edges of ponds or near koi pools as the sap in the water can be fatal to fish. In some cultures, the sap is used for poison arrows or to stupefy fish. My family physician once contacted me saying he’d been gardening and had an outburst of splotched and itchy arms and inflamed eyes with blurred vision. He’d gotten it while gardening and wondered if I had any ideas.

I responded, “My hunch is you’ve been cutting back …. [I named and described the plant] ... and you let that milky sap get on your hands and then rubbed your eyes.”

“Yes! Yes! That’s it!”

I instructed him to get in the shower and scrub thoroughly, starting with his hands, followed by his arms and then rinse his face and flush his eyes with clean, lukewarm water. I got a thank you note that made me feel like a horticultural Jonas Salk. I’d be lying if I said I wasn’t pleased with myself.  

Plants in 1- and 5-gallon cans will be in bloom in nurseries now, ready to put into your garden.

So, follow the yellow brick road to your favorite nursery and get one, two or three of these eye-popping, easy-to-grow euphorbias and stick them wherever you’d like to add some real emerald punch to your garden. For at least two months of the year, and likely even when the plant is not sporting its flamboyant flowers, your eye will be drawn to the spot. You’ll be euphoric over your euphorbia. It will put you somewhere over the rainbow!