How often to water newly planted young trees?

Asked October 4, 2017, 10:02 AM EDT

I have three newly planted young trees two days ago. Dogwood (caliper: 3.5 in.), Japanese Maple (caliper: 3.5 in.), Flowering cherry (caliper: 5 in.). I just soaked them with 10 gallons of water each last night. I read online about watering young trees. They said, check the soil. If the soil is wet or moist, do not need watering. But in the same breath, newly planted trees will benefit from daily watering for two weeks after planting. I found it contradictory. How often and how much should I water these newly planted young trees?

Spokane County Washington trees and shrubs irrigation and water management

1 Response

Hello and thank you for contacting us,

It sounds like you've planted some beautiful trees and we'll do our best to help you get them off to a good start. You can also contact us directly at 477-2181 or mastergardener@spokanecounty.org.

As for the contradictory advise about watering, the goal is to keep the soil moist around the tree roots, without drowning them. In most cases, especially with trees planted in the spring, it can take watering daily to keep the soil moist. In the fall, or in any cool weather, it may not take daily watering to keep the roots moist, because water isn't evaporating as quickly as it does in the heat.

Maybe what they should have advised is to check the soil every day, and be ready to water daily. The critical issue is not to let the roots dry out, and that is accomplished by keeping the soil moist, not dry or soaking wet. You can adjust the amount of water up or down based on the season and the moisture level in the soil.

Another issue to be aware of is how well your soil drains. How often you water newly planted trees depends on soil drainage. Soils that drain quickly will require more frequent watering than those that drain slowly. The best way to know how often and how much to water is to check the soil moisture down to 6 inches below the surface, and water when dry. Fast draining, sandy soils that are common around the cities of Spokane and Spokane Valley may need watering daily. Slower-draining soils like those around Greenbluff, Saltese, and areas south of the cities will be okay with less frequent watering.

The general recommendation for watering new trees is to give them about 1.5 gallons per inch of trunk caliper at every watering. That would be 5.25 gallons each for the dogwood and maple, and 15 gallons for the cherry. This is only a starting point however, as the goal remains evenly moist soil around the roots. You can use these recommendations as a starting point and adjust up or down from there based on soil moisture levels. You can also stick with the 10 gallons each if that is working, but you might give a little extra to the cherry.

I hope this information helps you, please feel free to contact us with any more questions. You might find the "Tree Owner's Manual" useful. You can find it at the following link: https://www.na.fs.fed.us/pubs/uf/tom/090202_tom_lr.pdf

Thanks for contacting us and best of luck with your new trees!