When it comes to watering trees, slow and deep is better than quick and shallow.

A short burst of water may wet the soil surface, but much of that water can evaporate or run off before it reaches the tree's roots. Slow, thorough watering allows moisture to move deeper into the soil where tree roots can use it.

🌳 ESTABLISHED TREES

Large, established trees usually have extensive root systems. When rainfall is insufficient, water the entire root zone (beyond the dripline), not just the area immediately around the trunk.

Think: SLOW • DEEP • THOROUGH

• Water slowly enough that the soil can absorb the water without significant runoff. (A soaker hose is a great tree watering tool).
• Spread water over as much of the root zone as practical, including beneath and beyond the outer canopy (dripline).
• Aim to moisten the soil to a depth of roughly 12-24 inches in the active root zone.
• Avoid short, frequent watering that repeatedly wets only the soil surface.
• During prolonged hot or dry weather, check soil moisture regularly and water when the soil at depth begins to dry.  Apply Hydretain to increase water retention in the soil.

A garden hose on a slow trickle, a soaker hose, or a properly adjusted sprinkler (not spraying on leaves) can all work. The goal is not how fast you deliver the water — it's how deeply and evenly the water reaches the roots.

HOW MUCH WATER DOES MY TREE NEED?

There is no simple number that works for every large tree. Water requirements depend on tree size, species, soil type, weather, rainfall, root-zone conditions and drainage.

Rather than watering by the clock, check the soil.

Push a screwdriver, soil probe or spade into the ground. If the soil is cool and moist several inches down, the tree may not need more water. If it is dry, it's time to water.

As a practical starting point, about 1 inch of water applied over the root zone can be useful during a dry period, but the correct amount and frequency will vary with site conditions. Heavy clay, sandy soil, slopes and compacted ground all affect how quickly water moves into and stays in the soil. 

Don't assume that more water is better. Waterlogged soil can deprive roots of oxygen and damage tree health. 

NEWLY PLANTED TREES NEED MORE ATTENTION

A newly planted tree has a limited root system and needs regular, consistent watering while its roots establish.

For a newly planted tree:

• Water thoroughly immediately after planting.
• During the first 1–2 weeks, water frequently — often daily, depending on weather and soil conditions.
• During approximately weeks 3–12, watering every 2–3 days may be appropriate.
• After that, continue regular watering, often weekly, until the tree is established.
• Adjust your watering to reflect substantial rainfall, soil type, drainage and hot or dry weather.

A SIMPLE NEW-TREE FORMULA

A useful starting guideline is approximately 1–1.5 gallons of water per inch of trunk diameter per watering for newly planted trees. As the root system expands, the watering area and requirements change.

The important part is how the water is delivered: apply it slowly over the root ball and surrounding root zone rather than dumping a large volume of water in one spot.

RAIN DOESN'T ALWAYS MEAN YOUR TREE IS WATERED

A brief, heavy rain can produce considerable runoff, especially on compacted or sloping soil. Conversely, a slow, steady rainfall can penetrate much more effectively.

Check the soil rather than relying only on what happened at the surface.

DON'T FORGET ABOUT FALL

Trees can still need water after summer heat has passed.

If fall is unusually dry, continue deep watering until after leaf drop. Adequate soil moisture going into winter can help trees better withstand winter conditions.

WATER THE ROOTS — NOT THE TRUNK

Most of the fine roots responsible for absorbing water are concentrated relatively close to the soil surface and extend well beyond the trunk. Established tree roots can spread far beyond the trunk and often beyond the canopy (dripline).

Don't concentrate all your watering at the base of the trunk.

Instead, distribute water across the root zone, while avoiding excessive watering of the trunk itself. 

3 RULES TO REMEMBER

1. WATER SLOWLY
Give the soil time to absorb the water.

2. WATER DEEPLY
Moisten the root zone rather than just the surface.

3. WATER WHEN NEEDED
Check soil moisture and adjust for rainfall, weather and soil conditions.

HAVE A TREE-WATERING QUESTION?

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