Reviving a Yellowing, Dry Euphorbia

Euphorbia Turning Yellow and Dry: Sunburn and Root Bound

A 10-year-old euphorbia (likely Euphorbia trigona) indoors in LA shows yellowing, drying stalks. It receives only 2 hours of direct sun daily, watered sparingly (monthly misting), and hasn't been repotted in 3 years.

Diagnosis

• Sunburn: Yellowing on stalks exposed to intense direct sun (even through glass) causes permanent scarring.
• Root-bound/old soil: After 3 years, the plant needs fresh, well-draining mix and a larger pot (pot height ≈ 1/3 plant height).
• Underwatering: Monthly misting is insufficient; water thoroughly when soil is dry.

Action Plan

1. Repot in fresh soilless cactus mix, slightly larger pot.
2. Remove dry, yellowed stalks with sterile knife (caution: sap can irritate).
3. Water deeply when soil is dry; use a wooden skewer to test moisture.
4. Provide bright indirect light; if moving outdoors, acclimate gradually with shade cloth.

Follow-Up

Owner confirmed sunburn from previous outdoor exposure. Sunburned tissue won't recover but won't spread. Repotting and proper watering will stimulate healthy new growth.