How to help trees survive the heat and below-average rainfall

Published on July 15, 2022

CITY NEWS pard-tree watering.jpg

It’s easy to see how valuable trees are in our daily lives particularly when enjoying their shade on a scorching summer day. Their worth goes well beyond shading in the benefits they offer, like providing oxygen and cleaning the air, enhancing property values, lowering utility bills and providing homes for birds and other wildlife. Trees are an investment that need occasional care, but provide great value to the community.

City Forester Craig Fox, a certified arborist, provided these tips for summertime tree watering:

  • Provide supplemental water. With such hot days and plenty of summer weather yet to come, it’s important to protect trees by offering some supplemental water as they try to cope with above-average temperatures and below-average rainfall. Mature, established trees generally fare better than small, young trees during droughts, thanks to their vast root systems in the top few feet of the soil. Young trees haven’t yet developed large networks of roots and will often decline far more quickly and with fewer signs of distress.
  • How much to water. To keep trees healthy and vigorous, apply 3-5 gallons of water per inch of trunk diameter every seven to 14 days during dry spells. Trees planted in the past few years will need to be watered more often to help ensure the roots aren’t drying out. If you have a thick lawn, more water may be needed since the grass roots will also take up water. Just like with lawns, watering before 10 a.m. or after 6 p.m. is best (and required in the case of sprinkler systems).
  • How to water. Soaker hoses, sprinklers, watering devices like “gator bags” or even a slowly dripping bucket can be used to apply water. It’s best to water the ground beneath the full canopy of the tree, not just around the trunk. Sandy soils like those found on the city’s east side or northwest side drain and dry more quickly, so watering may need to be more frequent depending on your conditions. Properly watered soil should feel slightly moist to the touch, not waterlogged or soggy. Be sure to follow any watering restrictions that may be in place
  • Take these extra steps. Besides watering, other things you can do to help your tree during stressful periods include:  applying a layer of mulch a couple of inches thick beneath the canopy, but away from the trunk; limiting pruning to only dead wood or broken limbs; avoid digging around the tree or disturbing the surface where delicate roots may exist; and don’t apply fertilizer to your tree.

What symptoms should I look for?

All plants, including trees, have different ways of coping with drought and may provide different signals alerting you to their need for help.

Wilting leaves are one of the most common symptoms of drought, but can also occur when plants are overwatered. Feel the soil to understand your conditions.

Trees may also have light green leaves which eventually turn yellow, brown or straw-colored. Crispy leaf edges that look burned or leaves falling to the ground are also common signs of water stress.

Be patient with your trees before deciding it’s too late to act. Many trees are drought-deciduous, meaning they shed some or all of their leaves as a way to cope with water stress. Cottwonwoods, sweetgums, mulberries and elms are well-known for this.

A tree may put on new leaves later in the year or simply wait until the following year to releaf, depending on the conditions and time of year.

How the city can help

If your neighborhood is lacking trees and you’re interested in planting to help shade and cool the community, learn more about the free tree programs offered by the Park & Recreation Department’s Forestry Section.

The Water Department has great information, resources and training to learn more about water conservation, irrigation systems and native plants.

 

 

Photo: Newly planted trees are more likely to show signs of drought stress than established trees. Young trees haven’t yet developed large networks of roots.

 

 

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