Tree Care Tips: Watering for Health and Longevity

Nearly every plant process, including photosynthesis, respiration and transpiration, depends on water to function properly. Water is just as essential as—if not more essential than—nutrients because it allows trees to absorb and transport what they need to grow and thrive.

Trees move and sway, and clients often share that they love watching their trees “dance in the wind.” Water plays a role here too, acting as a natural lubricant that allows trees to bend more easily. During drought conditions, trees can become desiccated, which may lead to broken or snapped limbs. Proper root development is key to stability, and regular watering helps make trees less susceptible to snow and wind damage.  

Trees absorb water primarily through their root systems, with significantly less uptake through bark, leaves or needles. Many well-meaning tree owners try to water their trees by spraying the leaves. While it’s true that photosynthesis occurs in the leaves and requires water, that water must first be absorbed through the roots and then transported upward. Watering the leaves or needles can cause more harm than good, as it creates a favorable environment for fungal diseases. Most water is lost through evaporation via the stomata—tiny pores on the leaf surface. The majority of trees replenish their water supply overnight and rely on soil moisture to do so.

Smart Watering Tips

Trees and shrubs need water to survive, making irrigation essential, but not always simple. While insufficient water is clearly damaging, over watering can be just as harmful. Summer is a critical period before trees shed their leaves in preparation for winter. Giving trees the right amount of water at the right time helps them thrive through this important transition.

Here are a few tips:

      • Watering is best done in the early morning or late afternoon, when temperatures are cooler  and foliage can dry before sunset.

      • Newly planted trees and shrubs should be irrigated twice per week. Established trees typically need water once a week. Adjust frequency based on rainfall, species and drought tolerance.

      • Avoid applying water directly to the trunk or leaves. Irrigate deeply in the root zone.

      • Fertilizing in autumn can support recovery from dry conditions and promote healthy spring growth.

Watering Newly Planted Trees in Chicagoland Summers

The amount of water a newly planted tree needs depends on multiple factors, including temperature, wind and rainfall. Each tree is unique, influenced by its species, soil type and root development. Proper watering keeps trees thriving—and tree owners happy.

Most newly planted trees decline or die from overwatering, as their roots require oxygen to grow. Here’s a general guide: 

How Often to Water

      • To check moisture, dig a small hole at the root level or use a tensiometer to measure water tension. Most large tree roots are found within the upper 12 to 18 inches of soil.

      • Water every one to three days for the first two weeks after planting.

      • On non-watering days, the soil should feel moist, but not soggy. If it’s soggy, skip watering.

      • Check moisture by inserting a finger or small trowel 6 to 10 inches below the surface. 

      • After two weeks, reduce watering to once or twice per week.

      • Continue weekly watering during the growing season for three to five years, or until the tree is fully established.

      • Adjust based on rainfall, drought or extreme heat.

Watering Mature Trees in Chicagoland Heat
 (More Than 5 Years Old)

      • Water once every seven to 10 days, depending on rainfall. Deep, infrequent watering is more effective than daily light watering. The best time to water is early morning or late afternoon when evaporation is lowest.

      • To check moisture, dig a small hole at the root level or use a tensiometer to measure water tension. Most large tree roots are found within the upper 12 to 18 inches of soil.

      • Provide 1 inch of water per week during the growing season, not including rainfall. For a large tree with a root spread of 30 by 30 feet, this equals about 560 gallons—roughly 10 full 55-gallon barrels. That’s nearly an hour of watering with a garden hose at full flow. Sprinklers reduce flow and increase watering time. To estimate how much water your sprinkler delivers, place a collection cup on the ground while watering.

      • Position sprinklers on the ground near the trunk, directing water outward toward the dripline. Avoid spraying bark or leaves. Soaker hoses use less water but must be moved frequently for adequate coverage.

      • Preserve soil moisture by adding a 2- to 4-inch layer of organic mulch. Mulch limits evaporation and reduces competition from turf and other plants. Keep mulch away from the trunk—“mulch like a donut, not like a volcano.”

A Little Care Goes a Long Way

In the greater Chicago area, where summer heat and sporadic rainfall can take a toll, consistent watering makes all the difference. Whether it’s a young sapling or a decades-old shade tree, giving trees the right amount of water at the right time helps them stay strong, stable and healthy for years to come.