Euphorbia martinii, a natural hybrid of E. characias and E. amygdaloides, was first discovered in the late 19th century in southern France. Smaller than its parents, Euphorbia martinii reaches no more than 2 to 3 feet in height. What it lacks in size, however, the small evergreen shrub makes up for in aesthetic appeal. Rosettes of dark green, purple-tinged leaves form an attractive base for the tall spikes of red-eyed, lime-green bracts that appear in late spring to early summer. Hardy in U.S. Department of Agriculture hardiness zones 8 through 10, this warm weather beauty cannot tolerate cold temperatures, but it thrives with only minimal care in the southern United States.
Select a planting site for Euphorbia martinii that has fertile, well-draining soil and receives full sun to partial shade. For the best results, choose an area that offers protection from strong winds, as most types of Euphorbia are susceptible to wind damage.
Plant Euphorbia martinii in early spring or fall. Till the soil to a depth of about 12 inches with a garden tiller just before planting, working in a 1- to 2-inch layer of organic compost if the soil is sandy or clay. Euphorbia does not require rich soil, but it must have good moisture retention and drainage. Dig the planting hole the same depth and width as the container in which the plant was previously growing.
Water your Euphorbia martinii plant once every two weeks during the heat of summer if it is located near other plants and trees. In areas where the plant does not compete for moisture, water deeply once every three weeks. Apply water once a week in hot climates if you've planted the shrub in full sun.
Remove spent flower stalks after they fade by snipping them off with garden shears as close to the stem as possible. Invigorate older plants by pruning them lightly in early spring before new growth begins. Prune away any damaged, diseased or wayward branches. Dip the pruned stems and branches in cold water before discarding to halt the flow of toxic sap.
Propagate Euphorbia martinii in fall by cutting off a piece of new growth from the base of the plant. Trim the portion to about 4 inches in length and remove the leaves from the bottom 2 inches, if any remain. Fill a 3-inch pot with 1 part sand and 1 part organic compost and plant the cutting about 1 inch deep in the mixture. Place the pot in a shady area until spring, then plant the rooted cutting in the garden.
Euphorbia martinii is not a heavy feeder and does not require supplemental fertilisation. When propagating Euphorbia, the cutting may not produce roots by spring. In this case, leave the cutting in a shady area until fall before planting.
Always wear gloves when handling Euphorbia martinii. Like all other Euphorbias, the plant's stems contain a toxic, milky sap that causes rash and irritation when it comes into contact with skin. Wearing long sleeves, trousers that cover your legs and goggles while pruning the shrub will help prevent injury.