How Trees Respond to Drought—and What You Can Do to Help Your Customers

By Cory McCurry, Arborologist, Rainbow Ecoscience

Technology is transforming every industry—and tree care is no exception. But can artificial intelligence truly replace the expertise of human arborists? Or is “Arborist Intelligence” still essential in the age of automation?

As climate change intensifies, droughts are becoming more frequent and severe. Understanding how trees respond to drought stress is essential for landscapers and arborists alike. In this article, we’ll explore how trees adapt to dry conditions and share expert tips on how to support tree health during drought.

How Trees Naturally Respond to Drought Stress

Trees are resilient organisms with built-in survival mechanisms. When water becomes scarce, they shift their energy from growth to survival. Here’s how:

• Stomatal Closure: Trees close the tiny pores on their leaves (stomata) to reduce water loss. This also slows photosynthesis.
• Leaf Drop and Adaptation: Some trees shed leaves early or grow smaller, thicker leaves to conserve moisture.
• Root Growth: Roots may grow deeper or spread wider to access underground water reserves.
• Energy Reallocation: Trees reduce growth, halt seed production, and may produce protective compounds to resist drought damage.

The ability of a tree to survive drought depends on its species, age, soil conditions, and the drought’s duration. While many trees can handle short dry spells, prolonged drought weakens them, increasing vulnerability to pests and disease.

Tree Drought Care: What You Can Do

1. Water Wisely

Deep, scheduled watering is key. Avoid overwatering but increase frequency during extreme drought.

• Trees: Apply 5–10 gallons of water per inch of trunk diameter (measured at breast height).
• Shrubs: Use 2–3 gallons per foot of height.

2. Mulch for Moisture Retention

Apply 2–4 inches of hardwood mulch around the base of trees and shrubs. Mulch helps:

• Lower soil temperatures
• Retain moisture
• Improve soil health

Important: Keep mulch away from the trunk to prevent rot. Avoid “mulch volcanoes,” which can stress trees further.

3. Use Proven Drought-Resilience Tools

Support your plants with science-backed products:

• Plant Growth Regulators (PGRs): Products like Trimtect and Cambistat reduce water demand by regulating growth.
• Soil Amendments: Use MoistureAide and humic acids (found in Biorush) to improve water uptake and root health.

What Results Can You Expect?

• Moisture Aid & Humic Acids: Improve soil water retention and reduce stress in mild drought conditions.
• Trimtect & Cambistat: Lower plant transpiration and help maintain hydration during severe drought.
• Proven Performance: Trimtect-treated plants show significantly lower canopy temperatures and better drought resistance than untreated controls.

By implementing these science-backed drought care strategies, combining wise watering, proper mulching, and the strategic use of PGRs and soil amendments, you can significantly enhance the resilience and long-term health of your customers' trees and shrubs. Proactive care ensures that landscapes not only survive the next dry spell but continue to thrive, safeguarding your clients’ investments and the environment.

Not sure which product is right for your customers’ trees and shrubs? We’re here to help. Contact your local Rainbow Ecoscience Territory Manager, Arborologist, or Tech Support for expert guidance.

Cory McCurry is an Arborologist with Rainbow Ecoscience