Public Works Department
Environmental Services

Fall & Winter Tree Watering Information

• Tree roots are not like carrots. Tree root systems can spread 2 – 3 times wider than the height of the tree. Most of the tree’s absorbing roots are in the top twelve inches of the soil. Water should be applied within the drip-line (the critical root zone in the box above).

• Water deeply and slowly. Apply water so it moistens the critical root zone to a depth of twelve inches. Methods for watering include a deep root fork or needle, soaker hose or soft spray wand. Apply water to many locations under drip-line. If a deep root fork or needle is used, insert the device no deeper than eight inches into the soil. The table at the bottom of this page has specific instructions for watering times.

• How much water should I apply? As a general survival rule, apply ten gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree will need twenty gallons per watering. Use a ruler to measure your tree’s diameter. The table at the bottom of this page has instructions for measuring the tree diameter and specific watering times based on the tree diameter.

• When should I water? Fall and winter watering, October – March, one to two times per month, depending on weather, temperature and soil conditions. Never water trees when the temperature is below 40 degrees or if there is snow cover. Spring and summer watering, April – September, three times per month, depending on weather and watering restrictions.

• Mulch helps conserve soil moisture. Apply organic mulch within the dripline, at a depth of four inches. Leave a six-inch space between the mulch and trunk of trees. Mulch materials may include wood chips, bark, leaves and evergreen needles.

• Consistent moisture is needed. Drought-stressed trees are more vulnerable to disease and insect infestations and branch dieback. Keep a watchful eye for anything that looks out of the ordinary.

DEVICE

<1"

1"

2"

4"

6"

8"

10"

12"

14"+

M
i
n
u
t
e
s

of

W
a
t
e
r
i
n
 g 

T
i
m
e

per

T
r
e
e

2

5

10

20

30

40

50

60

70+

Deep Root Fork
 (2 gpm*)

2

5

10

20

30

40

50

60

70+

Deep Root Needle 
(2 gpm*)

1

3

5

10

15

20

25

30

35+

Soft Spray Wand 
(4 gpm*)

2

5

10

20

30

40

50

60

70+

Soaker Hose (2 gpm*
50 ft hose w/restrictor)

*gpm=gallons per minute

Tree watering information provided by Denver Water, Front Range Urban Forestry Council, and the Colorado Tree Coalition.