Provo City

Watering

Tree Care

How often should you water your trees?
It depends. Different species of trees have different water needs. Some trees require lots of water; other trees are well adapted to arid conditions and require very little. The age and condition of your trees also influences how frequently you will need to water. Young, newly-transplanted trees require more frequent watering than do mature, established trees. Soil type, air temperature, humidity, light levels, and wind movement will also influence how often you will need to water your trees.
 
Typically, young and newly transplanted trees should be watered once every two to three days. Mature trees should be watered every seven to ten days. To gage exactly when your tree needs to be watered, gently dig down a couple of inches into the soil and feel around. If the soil feels wet or moist, do not water. Check the soil again in another day or two. If the soil feels dry, go ahead and water.   
  

Watering Techniques
  • Frequent, shallow irrigation should be avoided. It encourages surface rooting which makes the tree vulnerable to desiccation. It also compacts the soil surface and interferes with water infiltration.
  • Infrequent, deep soaks are better for trees. They promote a deeper root system and more drought-tolerant trees.
  • When watering, try to let the water soak down to a depth of about 18 inches.
  • Let soil dry out between irrigations. This allows for some natural shrinking and swelling, which improves soil structure.
  • Do not water trees directly at the trunk. This could lead to collar rot and other disorders. 
  • Distribute water evenly around the tree.
  • Try to avoid runoff. The water application rate should be slow enough so that the water is absorbed in the soil.  
  • Sprinklers are not the ideal way to water trees.
  • Often a good way to irrigate a tree is to leave a hose on with just a slow trickle coming out. Set the hose at least 3 feet away from the base of the tree and leave it for some time. Move the hose around the tree until the entire drip line has been watered.
  • Watering a tree on a daily basis is unhealthy and should be avoided.
 
What time should I water?
  • The best time to water trees is during the late night or early morning. Evaporation is minimized, and leaves have time to dry completely during daylight hours.
  • Evening is another good time, but only if you water after dew has formed on the leaves. Prolonging the period when a leaf is wet, could lead to fungal diseases.
 
Suggestions for Minimum Irrigation
  • Group plants that have similar water needs together.
  • Know the approximate root depth, and do not water past it.
  • Identify soil type and its water-holding capacity.
  • Test application rate and distribution uniformity, make adjustments if needed.
  • Water at the right time to minimize evaporation.
  • Mulch—mulch will help to keep water from evaporating out of the soil. 
 

Overwatering 
Overwatering your tree can be very harmful. It can lead to root and collar rot, root suffocation, death of beneficial soil organisms, a propensity towards topping, and a predisposition to other stresses. The symptoms of overwatering are similar to drought symptoms—wilting, leaf drop, yellowing of leaves and other off-colors. The best way to tell if you have an overwatering or under watering problem is to poke around the soil. Naturally, dry soil is indicative of drought stress. 
   

 
Autumn Watering
Water trees throughout the autumn. Tree roots will continue to grow as long as the soil is not frozen, and because the tree no longer has any leaves to support, root growth will be unhindered. Continue to water trees as long as the ground is not frozen. In Utah, the ground often does not freeze until the middle of November. This practice of watering trees throughout the autumn will increase the tree’s overall vigor.

 


Winter Watering
Winter droughts are just as much of a problem for trees as summer droughts. Occasional watering throughout the winter can be extremely beneficial, particularly for conifers as they are not dormant in winter. Keep in mind watering can only occur when the soil and trees are not frozen.

 
 
Works Cited
  1. Harris, Richard W., Clark, James R., and Matheny, Nelda P. 2004. Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines, Fourth Edition. Prentice Hall, Upper Saddle River, NJ.
  2. Lilly, Sharon J. 2001. Arborists’ Certification Study Guide. International Society of Arboriculture, Champaign, IL.
  3. Trees Are Good. 2004. Proper Mulching Techniques. International Society of Arboriculture, Champaign, IL. 
  4. Trees Are Good. 2008. Winter Tree Care Tips for Homeowners. International Society of Arboriculture, Champaign, IL. http://www.treesaregood.com/pressrelease/press/WinterTreeCare.aspx
  5. http://extension.usu.edu/files/publications/publication/HG-523.pdf
  6. http://extension.usu.edu/forestry/HomeTown/Care_Injuries.htm