Tree Planting and Care

How to Properly Water Your Trees

By Arbor Day Foundation | July 27, 2018

Guest post by John Lang of Friendly Tree.

Now that summer is in full swing, watering your trees properly is one of the best ways to keep them healthy and stress-free. With much of the Southwest United States currently in drought conditions, consistent watering is key to happy trees. But did you know — the most common watering mistake is actually too much water?

Whether it’s too much or too little, watering can be tricky if you don’t know how to do it. Follow this guide to ensure your trees make through summer with flying colors:

When to Water

During a summer afternoon, up to half of the water can be lost to evaporation. The best time to water is in the morning or evening, so the roots have a chance to absorb most of the water.

Unfortunately, there’s no magic schedule for watering trees. How often you should water will depend on the size of your tree, soil conditions, and weather conditions. Newly planted trees require much more water than established ones.

The best way to determine when trees need water is to check the soil. What you’re aiming for is moist — not soggy — soil. In the absence of rain or moisture, check the soil with a garden trowel to a depth of two inches. If the soil is dry to the touch, your tree needs water.

How Much

The rule of thumb for established trees is 10 gallons of water for each inch of the tree’s diameter. You can use a ruler at knee height to measure or just use your best guess.

Deeper is Better

Perhaps the most important element of watering when it comes to trees is the “how.” Slow and deep is your best bet, which is why drip lines are the preferred method of watering (although spray from a garden hose will certainly work). Drip irrigation also loses less water to evaporation compared with overhead watering or sprinkler systems.

Deep watering allows the critical root zone to take up adequate moisture. When setting up a drip line, be sure it extends to the entire area beneath the tree’s canopy and to a depth of 10 inches if possible.

Consistency is Key

Allowing the soil to completely dry out — or allowing it to stay soggy — will result in a tree that is stressed and therefore more prone to disease and infestation. Keeping the soil consistently moist is essential to healthy trees.

Choosing the Right Species

In regions where drought is typical, choose drought-tolerant species when planting new trees. Drought-tolerant trees are adapted to dry climates and will not only grow better, but help you to conserve water as well.

Newly Planted Trees

Young trees are still establishing their root systems and therefore need more water. Water newly planted trees once a day for the first couple of weeks after planting, and once a week after that during the growing season.

Remember to check the soil to ensure you are not over watering. Once the roots begin to extend beyond the root ball, you can water on a normal schedule.

Mulch is Your Best Friend

Mulch is a highly effective way to keep the soil from drying out quickly, especially during excessive heat. Applying mulch 2-4 inches deep will help conserve moisture and regulate the soil temperature.

Ask an Arborist: Why do we Mulch? 

Water Year Round

Don’t forget to water your trees in the winter during dry spells. Just because they are dormant doesn’t mean your trees aren’t growing. Water when air and soil temperatures are above 40 degrees F and when there is no snow cover. Your trees will thank you later!

 

About the Author

John Lang is a Certified Arborist and a member of the Friendly Tree team, a family-owned New Jersey tree care service, dedicated to the thoughtful and careful maintenance of your trees and shrubs. Friendly Tree Service has been in business for 26 years and remains passionate about trees and nature. With a highly trained staff that treats every property as their own and state of the art equipment, Friendly Tree is on the cutting edge of the art and science of Arboriculture.

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  • Connie July 18, 2019 at 7:08 pm

    Tree suckers at bottom of tree. 4 yr old cotton less cottonwood trees. Do I cut them off? When is best time & how to do safely?

    • Sheereen Othman August 29, 2019 at 9:20 am

      Hi Connie,

      The best way is to cut the sprouts down as low as you can. Prune and remove the shoots as you see them grow to help keep it manageable. Here is a great article from Davey Tree Experts with more details on how to manage suckers.

  • Dolores Salazar July 2, 2020 at 9:45 pm

    New trees but leaves dry out as soon as they sprout.. Help

  • Pablo E. July 28, 2020 at 1:49 pm

    I have two comments…
    Keeping the soil consistently moist is essential to healthy trees, true, however, most people not involved in the tree business can’t tell the difference between moist and wet, which to most, is a synonym. Thus, I usually instruct tree owners to test soil 4″-6″ deep. Squeeze the soil by making a fist. Note if water trickles between knuckles then to wet… when opening hand and soil crumbles, then too dry and it needs watering, otherwise, tree does not require watering, wait until soil dries a bit more..
    Mulch is Your Best Friend, might be so when properly applied. I have seen to many trees under-perform because of improper usage of mulch. Never ever pile mulch against the trunk. This is a sure way to attract insects laying eggs and voila, a plague is born; furthermore, the mulch acts as a sponge, which by holding moisture destroys the bark of the tree at the crown. Best to keep mulch away from the trunk by at least 6″. Finally, refrain from using dyed mulches as these include mineral and biological coloring. Manufacturers state its safe to use on trees, however, no one has tested if it is safe for the soil life (nematodes, worms, amoeba, fungi, etc).

  • Jim July 30, 2020 at 10:07 pm

    10 gallons per inch of diameter? That’s alot of water.

    • The Dude August 27, 2020 at 4:24 pm

      Yeah that’s what I was thinking? My new 20f plum has 3.25 diameter so 32.5 gallons of water…

      What I have done is drill two small holes in a 5 gallon bucket and placed it on the rootball area and let it drain out – about 5 gallons in 5 hours. …every 3 days. Seems to be working perfectly trees are healthy, leaves look good. soil is consistently moist to about 8 inches without being wet (as far as I can check)

  • Tom September 4, 2020 at 1:33 pm

    Is that 10 gallons per inch per week? Per month? Give us a time period., please.

    • Dave September 29, 2020 at 6:38 am

      That is 10 gallons per inch each time you water. WHEN you water depends upon your specific weather conditions. You would water enough to keep your soil moist (not dry, not wet). Therein lies the trick – like Goldilocks finding the porridge that was just right. So, check your soil when you THINK you should water and if too dry (see above) water immediately and check again a day earlier than you did the last time. If too wet, wait another day or two and check again. Then repeat. Watch the weather conditions (temperature as well as humidity). If you do this enough times you can soon figure out pretty well when it is time to water. You will also need to pay attention to the type of tree you have as drought tolerant trees (I live in central Texas so we have a number to choose from) and I try to wean them off of supplemental water as they establish. They are local native trees and should accommodate our long dry spells. I still watch the tree for signs of stress (they are very good at telling on themselves) and will turn on the irrigation systems when I see that. Sorry that there is no perfect formula for everyone. Hope this helps you set a path to success.

    • Tim October 1, 2020 at 1:50 pm

      Exactly

      The measurement is meaninglessness unless a time period is provided.