Watering Your Trees: How Much Is Too Much?

Little gardenerHow Much And How Often Is Enough?

According to recent data, cities in the Metro DC/Northern Virginia area average anywhere from 3 to 4 inches of precipitation during the wet summer months. In the summer months with temperatures surpassing 90 degrees with a high amount of humidity, it can be hard to determine how much water your tree needs in addition to what nature is providing. Trees receiving inadequate amounts of water will exhibit wilting, leaf scorch, and dropping of leafs and branches.

As a general rule of thumb, the bigger the tree, the more water it will need, with the average amount equal to 10 gallons per inch of diameter of the tree. You can determine approximately how much water your tree will need by multiplying the tree’s diameter (measured at knee height) and multiplying it by 5 minutes, which is about how long it takes to produce ten gallons of water from a hose at medium pressure. For example, a tree with a diameter of 5″ will need 50 gallons of water per watering, which would take about 25 minutes to produce.


    • Focus on the critical root zone when watering. Wetting foliage is a waste of water and can promote the spread of diseases.
    • DON’T use a sprinkler. This only wets the top layer of soil and doesn’t properly water the tree.
    • Water in the morning to avoid evaporation and to help trees deal with the heat throughout the day.
    • Water deeply and thoroughly 1 to 2 times a week.
      • Put your normal hose somewhere in the critical root zone.
      • Turn hose on to a dribble
      • Leave for 2-3 hours
      • Move the hose to a different spot in the critical root zone and leave for 2-3 hours. Repeat this step 1-3 times.
    • You want the soil to be moist but not soaking. You should NOT be able to make a mud ball out of the soil.
    • It’s okay for some portions of the soil to be wet and some to be dry.

Other Watering Tips:

  1. If your children have a plastic pool, dump the water around the base of your tree to conserve water.
  2. The best time to water is during the early morning or evening hours. Although not harmful, during the day when the sun is the brightest, the heat can cause evaporation, and not allow the tree to completely absorb the water, making watering inefficient.
  3. As a general rule, it is better to water deeply rather than more frequently in order to better penetrate the tree’s root system. This is particularly important with younger trees, as a shallow watering will encourage the roots to grow closer to the surface, which can cause other health problems for the tree.
  4. Avoid watering the trunk of the tree. Excess and frequent watering of a tree’s trunk can cause rotting.
  5. Do not over water your trees as this can cause just as much damage as too little water. After a good watering, the soil should be moist, not water-logged.

If you have a Canopy Protection Program you can relax knowing our plant health care technicians will notify you if your tree is being over or under watered.

2 thoughts on “Watering Your Trees: How Much Is Too Much?”

  1. Susan johnson says:

    My 3 yr old red maple has had spots on leaves, purpled to black, waxy. Leaves begin to curl up. I’ve treated with hydrogen peroxide spray. I’m exptremely sensitive to some of the pesticide/ fungicide things on market.
    I’ve picked leaves off as far as I can reach up but tree is now about 20’. & picked up fallen leaves. What can I do? And what can I use?

    1. Rtectree says:

      Hi Susan,

      I’d suggest reaching out to a Certified Arborist. It can be difficult to diagnose issues without seeing the tree in person. If you’re wary of pesticides/fungicides you may want to look into more organic options such as beneficial insect release and organic sprays. If you’re in our area we’d love to help just give us a call at 703-573-3029. If you’re out of our area we suggest going to the TCIA website and finding an accredited tree care company that operates in your zip code.

      Thanks for your comment!
      -Samantha H.

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