Yellowing Vinca, Geranium, Daisy in South Texas Heat: Water, Mulch, Drainage

Rio Grande Valley gardener's vinca, geranium, and daisy leaves yellowing in extreme heat. Asked about fertilizer, water, or other fixes.

Likely Causes

• Overwatering + poor drainage: Wet soil suffocates roots → yellowing.
• Unmulched soil: Hot sun bakes bare soil, rapid drying → stress.
• Insects: Sucking pests cause yellowing.

Action Plan

• Check soil moisture. If wet, improve drainage.
• If dry, water deeply daily during heat waves.
• Mulch 2 inches (shredded leaves, hardwood) to stabilize root zone temperature.
• Loosen planting holes with compost/potting soil at planting.

Mulch + drainage + deep watering = steady root zone. Without mulch, wet/dry swings make care nearly impossible.