Euphorbia is a very large genus of plants with more than 2,000 species. About 1,200 of them are succulents, some with bizarre shapes and wide, fleshy leaves and others that look remarkably like cacti, complete with spines. They are often grown for their architectural shapes and fascinating foliage, but a few are known for their flowers. Most Euphorbias bloom in spring or summer and go dormant in winter.
The non-succulent deciduous Euphorbia plants include some of the most familiar such as milkweed and the popular holiday plant, poinsettia. Most of the succulent euphorbias are not frost-tolerant. There are a few evergreen species, like creeping wood spurge (Euphorbia antisphilitica), cushion spurge (Euphorbia polychroma) and donkey-tail spurge (Euphorbia myrsinites: not to be confused with the donkey's tail succulent) that will survive down to USDA Plant Hardiness Zone 5, but most Euphorbia species fall into zones 6 through 9, with a few hardy only in zones 10 and 11.
Euphorbia species often go by the common name of spurge. You will also see some with more descriptive common names, such as the "Basketball Euphorbia" (Euphorbia obesa).
Euphorbias are very easy to care for. They require a little pampering to become established, but once they are, they are self-sufficient. In fact, more die from too much care and watering than from neglect. Here are some tips for getting your Euphorbia plants off to a healthy start.
Euphorbias can be grown from seed, but they can be difficult to germinate (or even find). This plant is usually propagated by cuttings. Fresh cuttings can ooze sap which can be a skin irritant, so you may wish to wear gloves.
Allowing the cut stem to dry overnight will improve your success rate of rooting the cutting, as will the use of some type of rooting hormone.
Soil: All Euphorbias, especially the succulent varieties, need well-draining soil. They will rot if left in the wet soil for a prolonged period. They are not particular about soil pH and will adapt to most soils, as long as there is good drainage.
Euphorbia plants prefer a spot in full sun, although they can tolerate partial shade.
Caring for Your Euphorbia Plants
While most Euphorbias are relatively love maintenance, they do have some specific requirements:
- Water: Unlike most succulents, euphorbia does not handle long periods of drought well. Your plants might need weekly watering during the summer. Water whenever the soil is dry several inches below the surface. Water deeply, but don't let the plants sit in wet soil, to avoid root rot.
- Feeding: To help your Euphorbias get established and growing well, add some organic matter, like compost, or a balanced, organic fertilizer to the initial planting hole. If you are growing Euphorbia in a container or if your soil is poor, feed with a half-strength fertilizer monthly.
Growing and Caring for Euphorbia
Pest and Problems of Euphorbia
Euphorbia plants tend to grow mostly problem free. Between the milky sap and the spiky needles, few animals find Euphorbias tempting. However, there are a few pests and diseases to be on the alert for.
- Mealybugs and spider mites are the most common pests. They will feed on the plants, weaken, and eventually kill them. The population of both these insects can increase to large numbers rapidly. Catching them early is your best chance of controlling them.
- Root rot occasionally occurs, but it's only a problem when plants are allowed to sit in wet soil. Provide well-draining soil and limit watering to when the soil feels dry a couple of inches below the soil surface.
- Although Euphorbias like humidity, they also need good air circulation or they will be susceptible to mildews. Try correcting growing conditions before you resort to spraying fungicide on the plants, which can harm Euphorbia leaves.
Suggested Varieties of Euphorbia for Growing
Some of the most popular Euphorbia plants include:
- Euphorbia grandialata—Start out upright and spread into a bush. Thorny. Coral red bracts in summer. Grows to 6 ft. high by 8 ft. wide.
- Euphorbia lactea—Fan-like scalloped branches and black spines. Grows to tree size (16 ft.)
- Euphorbia milii, "Crown of Thorns"—Thorny, bushy plant that loves warm, wet weather. Bracts in shades of red, yellow, orange and white will open throughout the year. Grows to 6 feet high by 5 ft. wide.
- Euphorbia obesa,"Basketball Euphorbia"—Round and plump, with reddish stripes. Can handle some shade. It gets more columnar with age; grows to 8 inches high by 5 inches wide.
- Euphorbia symmetrica—A subspecies of Euphorbia obesa, it remains small and round.