Diagnosing Brown Leaves on Carolina Jasmine in Texas

Carolina jasmine (Gelsemium sempervirens) turning brown and dying back in Schertz, TX (Zone 8b) after three years suggests a cultural or disease issue, not insects—especially since a garlic-based spray didn't help.

Likely Causes

• Fungal leaf spot or root rot from poor drainage or excessive moisture. Jasmine hates "wet feet."
• Drought stress despite your watering—clay soil can repel water when dry, then suffocate roots when wet.
• Nutrient deficiency (especially iron in alkaline Texas soils) causing chlorosis and dieback.

Action Plan

1. Remove all brown/dead foliage and dispose of it in trash (not compost) to reduce inoculum.
2. Apply a copper-based fungicide or chlorothalonil (Daconil) per label, covering all foliage and stems. Repeat in 10–14 days.
3. Improve drainage: Aerate around the root zone, incorporate compost, and ensure water doesn't pool.
4. Water deeply but infrequently—once a week in dry spells, soaking the root zone to 12 inches. Avoid daily light sprinkling.
5. Hold fertilizer until spring. Then apply a balanced 10-10-10 or a slow-release shrub fertilizer.
6. Clean the bed: Remove weeds, leaf litter, and decaying mulch. Refresh with 2 inches of pine bark mulch, keeping it off stems.

When to Worry

If new growth also browns, or entire stems die back to the ground, the root system may be compromised. In that case, consider replacing with a more disease-resistant vine like crossvine (Bignonia capreolata) or coral honeysuckle (Lonicera sempervirens).

With prompt sanitation and corrected watering, established Carolina jasmine often recovers fully.