July 2, 2012
to dry soil conditions, NENA and the Minneapolis
Park & Recreation
Board Forestry Section are encouraging residents
of Minneapolis to water their trees. Young and mature
trees both are showing severe signs of
stress and many are dying due to lack of moisture.
Mature trees, especially the American elms and mountain
ash trees are more susceptible to disease and pest
infection when so stressed.
needs water? All trees need watering this summer. Please start by watering newly planted
and young trees in both your yard and along the boulevard. Mature trees also need watering, but they will require a different technique.
are our trees in trouble? Currently
our soils are very dry for the ninth summer in a
lack of rain and unusually hot conditions
have contributed to the dry soil conditions. If
the small feeder roots near the surface
dry out, the tree will die. It will take more than a two-inch
rainfall to bring the soil moisture back to good growing
conditions, so keep watering even if it rains.
Where and how should I water? Water does not move sideways in soil. You must apply water directly over where you need water in a soil. The most satisfactory means of uniformly distributing an adequate amount of water to a tree is with a garden hose – open-ended for newly planted trees and with an oscillating lawn sprinkler for established trees. Perforated soaker hoses and buckets can also be used, but the results are less satisfactory.
For young trees, concentrate water over the root ball, as well as the planting area, to assure survival. This is most easily accomplished by creating a circular mound of earth 3 to 4 inches high around the tree at the edge of the planting area (backfilled hole). The mound of earth serves as the dike of a reservoir. When filled, the reservoir will contain enough water to soak the soil of the backfill and the soil contained in the root ball. If not using a mounded reservoir, water by placing an open-ended hose under the crown of the tree, turn the water on at a slow trickle and water for two (2) hours. If a garden hose is not available, apply at least 10 gallons (two, 5-gallon pails of water) slowly
around each young tree every 7-10 days.
Large established trees can be watered by wetting the soil surrounding the plants roots. This area is known as the “root zone” and it serves as a storage tank from which the tree draws moisture. Most roots of trees spread 1½ to 3 times as wide as the tree’s canopy but not very deep – usually in the upper 6 to 12 inches of soil – depending upon the size of the plant and the type of soil. Shallow or compacted soils can cause shorter and wider root zones. Water the complete root zone each time you irrigate. Use your lawn sprinkler,
so that each time you water the grass around or near a tree, you
are applying two inches of water. How do you
know when you have put down 2" of water? Place several lidless, soup-sized cans in the radius of your lawn sprinkler. When the average water depth in the cans is 2 inches, you have provided enough water to moisturize soil to a depth of 10-12 inches.
How often do I need to water? It's
very important to water trees once every seven to ten days during the growing season when dry soil conditions exist.
Avoid frequent light watering. This promotes the development of shallow root systems that are susceptible to summer heat stress and winter injury. Water infrequently but deeply (at least 6 to 8 inches into the soil) and allow the soil to dry out between applications.
Be careful not to overwater. Overwatering forces oxygen out of the soil and results in oxygen starvation of roots. This causes root death and leads to the decline of the tree.
Depending upon soil texture, bulk density, daily temperatures, and rainfall amounts, 1 to 3 inches of water per week should keep an established tree healthy. Five gallons of water per square yard of surface area is about 1 inch of water.
Newly planted trees will benefit from daily watering for the first one or two weeks, applying approximately 1 to 1½ gallons per-stem-caliper inch per watering. Thereafter, water trees every two to three days for the next two to three months and then weekly at the same rate until established.
Source materials: University of Minnesota Extension Service and the Minneapolis Parks and Recreation Board
Updated July 22, 2006
can I keep the soil moist around tree roots? It
is best to maintain a 4-inch layer of mulch (such
as wood chips) around your trees.
However, do not
heap mulch up against the tree trunk. To avoid rot
and disease, place the mulch so that it is
kept a few inches away from the trunk of the
or newly planted trees should have at least a
two foot radius of mulch placed around the
trunk of the tree.
older trees, a 6-foot or larger radius
is effective and attractive.
can I obtain 'free' mulch? The
Park & Recreation Board's Forestry
Section makes wood chips available to anyone who
can use them. There are three sites in, or near, Nokomis
Nokomis Parkway site
On Lake Nokomis Parkway between E 50th Street and
22nd Ave S. (North side of Lake Nokomis.) Wood chips
are in a parking lot on the lakeside of the parkway.
On E 58th Street between 28th Ave S and 31st Ave
S. This site is just north of Crosstown 62
(east of the 28th Ave
exit). Wood chips are in the parking lot on the
Bossen field side of the street.
From the intersection of 46th Avenue S and Godfrey
Parkway, travel south on 46th Avenue S and enter
the road to the Minnesota Veteran's Home. Wood chips
are in a lower parking lot on the west side
of the road.
Minneapolis Park and Recreation Board also has
mulch sites located in neighborhoods throughout the
city. For a list of all sites, click