Euphorbia mammillaris variegata

Botanical Name — Euphorbia mammillaris variegata

Common Name — corn cob Euphorbia, Euphorbia ‘White Rocket’

Plant Family — Euphorbiaceae

Background

Euphorbia mammillaris is native to South Africa where it grows in thorny bushlands. It produces a thick main stem with smaller, club-like lateral branches that grow near the base of the plant. The variegated version of the plant is speckled white and green and is more sensitive to direct sun than its entirely green counterpart.

Growth Requirements

Sun

‘White Rockets’ require very bright light, with at least five hours of direct sun being ideal. Indoors grow these plants in a south-facing window.
Variegated varieties are especially prone to sunburn, so if growing outdoors situate this plant in an area with light shade, that will protect it from intense, mid-day sun.

Temperature/ Humidity

Euphorbia mammillaris will thrive in high temperatures, above 70 ºF. They can withstand cold up to 35 ºF.
These semi-arid plants prefer arid environments and will grow well in moderate humidity but it is not required for them to thrive.

Water

Euphorbias prefer dry conditions. To water properly, saturate the soil fully and allow the medium to dry out entirely between waterings.
Water consistently during the spring and summer, and reduce watering during the fall and winter months.

Soil/Roots

These succulent plants prefer a gritty, well-draining mix. A cactus or succulent soil would work great. Soil mixtures can be amended with sand or fine pumice up to 50% to improve grittiness and drainage.

Flowering

‘White Rockets’ typically bloom from early spring to early summer. Inconspicuous, yellow cyathia are borne at the tips of stems.

Fertilization

These plants typically do not require fertilization, though it can be applied to give plants a boost during the growing season or to replenish tired soil.
Use a balanced fertilizer diluted at half-strength, once a month, during the growing season only. Cease fertilizer use during the fall and winter months.

Propagation

These plants are easily propagated from offsets branching stems. Separate offsets using sharp shears. Allow cuttings to callous for a few days before placing it in soil. Keep the soil fairly dry until roots start to develop then water as you normally would.

Health

Diseases

Euphorbias tend to be resistant to pests and diseases but there are still some things to look out for. Mealybugs and spider mites are the most commonly found pests. Treat affected plants with an insecticide or diluted neem oil.
Root rot and powdery mildew are other concerns to watch out for and most often occur as a consequence of overwatering, or poor air circulation, respectively. Always err on the side of underwatering and grow your plant in a spot where it will receive good airflow.

Maintenance (pruning, legginess, repotting)

These plants require little to no maintenance. Euphorbias grow fine, shallow roots and prefer to be root bound. Repotting should be done only once every two to three years. Up pot plants into a container that is 2 inches wider in diameter to give the plant plenty of room to continue growing.

Toxicity

All Euphorbia plants contain a poisonous sap that is very toxic if ingested and highly irritant if contacted with skin. Keep out of reach of pets and children. Wear gloves and take great care when handling this plant.