Crown of Thorns
Euphorbia milii
Through the year 🗓️
☀️ Summer now
Peak bloom season. Water a touch more generously in strong sun and don't let it wilt hard.
🍂 Fall
Taper water and stop feeding as day length drops; expect some leaf thinning.
❄️ Winter
Water sparingly, keep it above 55 °F in your sunniest window, and it may keep flowering right through.
🌱 Spring
Prune leggy stems (gloves and rinsed blades, since the sap is caustic) and resume monthly feeding.
The details
Light & placement
- Light
- Bright light with 3–4+ hrs of direct sun; the more sun, the more flowers
- Ideal PPFD
- 400–700 µmol·m⁻²·s⁻¹
- Grow-light distance
- 8–14 in below LED
Water & feed
- Watering method
- Soak-and-dry, but not bone-dry: water deeply when the top 1–2 in are dry. Kept slightly moister than a typical succulent, it blooms; kept desert-dry, it drops leaves.
- Fertilizer
- Balanced feed at ½ strength, monthly in spring–summer to fuel near-constant flowering.
Home & habit
- Soil
- Gritty, fast-draining cactus/succulent mix; pH 6.0–7.0
- Humidity
- Low (30–50%)
- Temperature
- 65–85 °F; keep above 55 °F
- Mature size
- 1–3 ft indoors
- Repotting
- Every 2–3 yrs in spring; gloves on, it bites
- Propagation
- Stem cuttings: rinse the milky sap off in cool water, let callus several days, then pot. Wear gloves.
When something looks wrong
- Overwatering signs
- Yellowing, dropping leaves with wet soil; soft blackened stems
- Underwatering signs
- Wholesale leaf drop; wrinkled stems; stalled blooming
- Common pests
- Mealybugs, spider mites, scale, thrips
Common problems 🩺
The usual suspects when Crown of Thorns looks unhappy. Most houseplant trouble is watering or light, not disease — see all plant problems if you are not sure which plant is the culprit.
Dropping leaves
Likely cause
Seasonal shedding, a cold snap, or overwatering.
What to do
Some loss in winter is normal. Keep it warm and let the soil dry between waterings.
Few or no blooms
Likely cause
Not enough direct sun — it flowers almost year-round given enough.
What to do
Give it 3–4+ hours of direct sun and feed through the growing season.
Soft, blackening stem base
Likely cause
Overwatering.
What to do
Gritty mix, thorough drying between waterings. The milky sap is an irritant — wear gloves when pruning.
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