Caring for Trees During Drought: Watering, Mulching, and Stress Management

We need trees, especially during drought. Trees reduce air pollution and erosion, create wildlife habitat, and mitigate urban heat islands—even hotter, drier conditions from excessive reflective pavement. Here's how to best care for your trees.

• Water beyond the drip line. Most trees lack tap roots (oaks and pines are exceptions), so watering, fertilizing, and mulching at the base doesn't reach the roots. Roots extend 1.5 to 4 times beyond the canopy; in heavy clay, 5+ times wider than the dripline.
• Ensure moisture reaches 12-18 inches deep. About 90% of tree roots are in the top 12 inches of soil. Use a soil probe each time you water to verify penetration.
• Remember trees if you remove the lawn. Many established trees depend on lawn irrigation. Removing grass causes deep stress. Plan for continued water and fertilizing.
• Watch for drought stress signs. Leaves may wilt, curl, or yellow. Deciduous trees show scorched brown edges or browning between veins. Evergreens turn yellow, red, purple, or brown. Stress weakens trees, inviting secondary insects or diseases later.
• If stress appears, skip fertilizer. Roots are especially susceptible to salt burn from fertilizers when water is insufficient.
• Mulch to retain moisture. Layer 4 inches of organic mulch (bark or evergreen needles) between waterings. Avoid stones—they increase temperature and moisture loss. Pull mulch 6 inches from trunk to prevent rot.
• Maintain proper pruning. Remove broken, dead, or diseased branches. Well-pruned trees have improved structure and stability, helping them withstand dry periods.