How to grow crown of thorns
Overview
Crown of thorns (Euphorbia milii) is a succulent shrub grown for its long-lasting, colourful bracts and thorny stems. It thrives in hot, dry positions and is highly drought-tolerant once established.
Varieties
- Euphorbia milii 'Short & Sweet' — Compact, dwarf form with red bracts, ideal for small pots.
- Euphorbia milii 'Pink' — Common pink-flowered variety, very free-flowering in full sun.
- Euphorbia milii 'Yellow' — Rare yellow-bracted form, often sold as a grafted plant.
Soil Preparation
Crown of thorns needs a sharply draining, slightly acidic to neutral soil (pH 6.0–7.0). Mix coarse sand or perlite into standard potting mix; for garden beds, add gravel to heavy clay. Avoid any soil that holds moisture for more than a day.
Growing Guide
Plant crown of thorns in a free-draining, gritty or sandy soil in full sun. Space plants 40–60 cm apart; they can be grown as a low hedge or in large pots. Water sparingly after planting until new growth appears, then allow the soil to dry completely between waterings. In subtropical and tropical zones, protect from heavy summer rain by placing under an eave or in a well-drained raised bed. Avoid any organic mulch that stays wet against the stem.
Care
Feed monthly from spring to autumn with a low-nitrogen liquid fertiliser (e.g., 2-7-7) to promote blooms. Prune lightly after flowering to shape and remove dead stems. Repot every 2–3 years in spring using a cactus mix.
Companion Planting
Pair with other sun-loving succulents such as Agave, Aloe, and Portulaca. Avoid planting near moisture-loving ferns or leafy greens that require regular irrigation.
Common Pests & Risks
Scale insects and mealybugs can cluster on stems and under leaves; treat with horticultural oil or a systemic insecticide. Spider mites may appear in dry, hot weather; increase air circulation or spray with water. Root rot from overwatering is the most common disease.
Troubleshooting
Yellow leaves: overwatering or poor drainage; reduce water and check roots. Brown leaf edges: low humidity or salt buildup; flush soil with rainwater. Stems rotting: fungal infection from wet soil; cut back to healthy tissue and repot in dry mix. No flowers: too much shade or high nitrogen; move to full sun and switch to low-N fertiliser. Leaf drop: cold shock or sudden temperature change; protect from frost.