Why Your Crown of Thorns (Euphorbia × lomi) Stopped Flowering

A 8–10 year old crown of thorns (Euphorbia × lomi, sold as ‘Somona’) hasn’t bloomed in 5 years despite healthy growth. Here’s how to encourage flowers again.

Key Factors for Flowering

• Light: This plant needs full sun—at least 4–6 hours of direct light daily. Moving it to a sunny bay window is the single most important step.
• Fertilizer: High nitrogen (first number) promotes leaves at the expense of flowers. Switch to a low-nitrogen, high-phosphorus fertilizer (e.g., 5-10-5) or a bloom booster.
• Pot size: Being slightly root-bound encourages flowering. Repotting into a larger pot often delays blooms. Only repot if the plant is severely root-bound.
• Water: Allow soil to dry between waterings. Overwatering suppresses flowering.
• Water quality: Hard tap water builds up salts. Use filtered, distilled, or rainwater.
• Age & genetics: Some hybrids are bred for a spectacular first bloom then rarely flower again. This may be the case.

Action Plan

1. Move to the sunniest window (south/west).
2. Switch to low-nitrogen fertilizer, apply monthly in spring/summer.
3. Water only when top inch of soil is dry.
4. Use pure water.
5. Be patient—flowering may resume in the next growth cycle.

If it still doesn’t bloom after a year of optimal care, it may simply be a shy-flowering hybrid. Enjoy the foliage!