Euphorbia spinosa aka Spiny Spurge

Euphorbia spinosa requires moderate care skills due to its specific growing requirements. While drought-tolerant and generally low-maintenance once established, this Mediterranean native demands excellent drainage—ideally scree, a dry wall, or gritty alpine compost. In colder regions, it may need protection in an alpine house. Success depends primarily on providing the right soil conditions and avoiding overwatering, which can cause root rot.

Euphorbia spinosa is a compact subshrub reaching 15-30 cm (6-12 inches) in height with a spread of 15-45 cm (6-18 inches). It forms a dense, mat-like mound over 2-5 years as it matures. The growth rate is slow, which is typical of plants adapted to nutrient-poor rocky Mediterranean soils.

Euphorbia spinosa is hardy to approximately -10°C (14°F), rated H4 by the RHS, making it suitable for most of the UK and USDA zones 7-9. In regions with colder winters, it should be grown in an alpine house or protected microclimate such as against a south-facing wall. The plant is native to Mediterranean rocky habitats and may go dormant during cooler months.

Euphorbia spinosa blooms from May through August, producing clusters of tiny, bright yellow flowers surrounded by yellow to yellow-green bracts. Like all Euphorbia species, the 'flowers' are actually cyathia—specialized inflorescences where reduced male and female flowers are arranged in a cup-like structure with nectar-secreting glands. The colorful display attracts insect pollinators including bees, flies, and wasps.

Euphorbia spinosa is exclusively an outdoor plant, thriving in rock gardens, scree beds, alpine troughs, and dry walls. Native to Mediterranean rocky habitats from France to Albania, it requires full sun to partial shade and excellent drainage. The plant is hardy to USDA zones 7-9 (RHS H4). In regions with harsh winters or wet conditions, grow it in an alpine house or raised bed with sharp drainage to prevent root rot.

Euphorbia spinosa can be propagated by seed, cuttings, or division. Seeds should be sown in spring in gritty compost; germination can take 2-6 months in cold conditions but occurs within 1-2 weeks with warmth. Softwood cuttings taken from basal shoots in early spring root within two weeks when planted in sandy mix after allowing the cut to callus for a day. Division can be done in spring by carefully separating established clumps. Always wear gloves when handling as the milky sap is irritant.

Three subspecies of Euphorbia spinosa are recognized by botanical authorities. Euphorbia spinosa subsp. spinosa is the typical form found across most of the Mediterranean range. Euphorbia spinosa subsp. ligustica occurs in Liguria, Italy. Euphorbia spinosa subsp. glabriflora is native to the Balkan Peninsula and features less hairy flowers, as its name suggests. All share the characteristic spiny stems and cushion-forming habit.

Euphorbia spinosa is pollinated primarily by insects including bees, flies, and wasps. The plant's cyathia (specialized flower clusters) feature bright yellow bracts and nectar-secreting glands that attract these pollinators. Research on Mediterranean Euphorbia species shows they have generalist pollination systems, with visiting insects carrying pollen between plants. The nectar glands and volatile compounds emitted by the cyathia are key attractants.

Euphorbia spinosa is generally resistant to pests due to its toxic, milky latex sap that deters herbivores and insects. The main threats are cultural rather than biological: root rot from overwatering or poor drainage, and cold damage in harsh winters. Mealybugs and spider mites may occasionally appear in alpine house conditions. Ensure excellent drainage and air circulation to prevent fungal issues.

Spiny Spurge’s native range is Worldwide.

Spiny Spurge does best in dry soil and should only be watered sparingly.

To keep your Spiny Spurge healthy, it's important to use a potting soil that won't retain too much moisture. A soil that drains well and contains perlite or vermiculite for drainage and some organic matter for nutrition is ideal. Adding a few handfuls of perlite to regular cactus soil from the store is an easy way to create this type of soil mix.

Spiny Spurge requires abundant, bright, and direct light to thrive. The best placement for this plant is within one foot of a window to ensure it receives enough light. If you live in an area with more extreme weather, such as hot summers or cold winters, you may need to adjust the placement of the plant accordingly. During hot summer months, it is important to place the plant away from full sun, as this can cause the leaves to yellow or burn. During cold winter months, it is best to move the plant closer to the window to take advantage of the extra light that can help it survive. By keeping an eye on the current weather in your area, you can make sure your Spurge is always in the right place to thrive.

Spiny Spurge prefers dry environments, so misting the plant to provide extra humidity and allow water to linger on the leaves can create an ideal environment for fungi that can be harmful.

The Spiny Spurge is characterized by its slow growth and doesn't need fertilization in addition to its potting soil. By renewing the soil in its pot once a year, it should have enough nutrition. Remember, plants get their energy from sunlight, not from any fertilizers.

There is no verified data on the toxicity of this plant in the records of Ploi. If any person, including yourself, a family member, or a pet, consume plant material with an uncertain toxicity level, it is advisable to seek the advice of a healthcare expert.

During the wintertime, it is common for Spiny Spurge plants to go dormant and their growth rate may slow down. Therefore, the amount of waterings should be spaced out more.