Supplemental Tree Watering During a Drought

As the growing season approaches, the impact of previous dry spells – often leaving our landscapes as much as 13 inches below average precipitation – remains a top concern for property owners. Watering trees in a drought like this becomes a vital plant care task to prevent long-term damage.

While all trees feel the effects of a dry season, younger and struggling trees are the most prone to water loss. To protect your landscape, it is essential to understand the mechanics of how to water trees properly, ensuring a balance between hydration and the oxygen roots need to survive.

Why Trees Need Supplemental Moisture

To grow and survive, trees rely on roots to deliver moisture above ground for photosynthesis. Without adequate water, this process slows down, leading to stunted growth and increased vulnerability to pests.

However, supplemental watering is a balancing act. While moisture is vital, roots also require oxygen to function. In waterlogged or oversaturated soil, oxygen is pushed out of the pore spaces. To keep your trees healthy during a drought, you must provide enough water for photosynthesis without creating an anaerobic environment that suffocates the root system.

Strategies for Deep Root Watering Trees

Most trees require roughly one inch of water every 7–10 days. However, lawn turf often absorbs surface moisture before it can reach the tree’s root system. To bypass this competition, you must focus on deep root watering your trees rather than frequent, shallow sprays.

• Check Before Watering – Pull back the mulch and check the soil 1–2 inches deep. If it’s dry, it’s time to water; if it’s moist, hold off to avoid waterlogging the soil.
• Optimal Timing – Water in the early morning or in the evening to prevent loss due to evaporation.
• Specific Depth – Aim to wet the soil to a 6-inch depth. This encourages roots to grow deeper, creating a more resilient tree.
• Mind the Drip Line – Avoid saturating the base of the trunk. Roots spread two to three times the width of the crown, so focus your efforts there.
  • For newly planted trees, focus directly under the crown as the root system is still compact.
• Protect the Foliage – Keep water off the needles and leaves to reduce the risk of fungal diseases, especially for pines, spruces, and crabapples.
• Note on Evergreens – Supplemental watering for evergreens should be continued until the ground freezes to help defend against winter desiccation.

Maximize Retention with Proper Tree Mulching

One of the most effective ways to retain soil moisture is through professional tree mulching. By creating a dedicated mulch bed, you eliminate competition from turf and keep the soil temperature regulated.

1. Clear the Drip Line – Remove turf from underneath the tree’s canopy.
2. Nutrient Layer – Apply a 1-inch layer of compost.
3. Organic Mulch – Follow with a 2–3 inch layer of organic mulch to lock in moisture.

Rebuilding Root Resilience

In cases of long-term water deficits, trees may need more than just a hose to recover. At Wachtel Tree Science, we utilize specialized treatments to rebuild a tree’s root system to improve water uptake.

• Mycorrhizae & Biostimulants – Treatments that stimulate root growth and efficiency.
• Compost Tea – Applications that build soil health and reduce disease potential

The ISA Certified Arborists at Wachtel Tree Science can assess the condition of your landscape and recommend the best course of action. If you’re concerned or have questions about watering trees in a drought, give us a call today to keep your trees healthy and beautiful.