CO-Horts Blog

Monday, November 5, 2018

Why Should You Water Your Trees This Winter

Why Should You Water Your Trees This Winter
Posted by: Andie Wommack, Douglas County Extension

2018 was another dry year for Colorado. 66% of the state is still experiencing some level of drought, with 37% in either a D3 (Extreme) or D4 (Exceptional) drought. Agriculture usually feels the effect of drought during the first year of a really bad drought, but the second year is when homeowners will start to feel the consequences of our lack of water. If it looks like we are going to be facing drought conditions again in 2019, you may experience watering restrictions in your neighborhood if you haven’t already. This could mean that you may not have the water available to play catch-up from not watering during a dry winter season.

Watering your landscape throughout the winter is crucial if we are not getting moisture. Trees should be watered ten gallons per inch of trunk diameter at knee height. If we get winter moisture, that amount can be reduced. Water to a depth of 12 inches since the majority of your tree’s roots are in the top 6-24 inches of soil. Ideally your trees should be watered three times in September, and then cut back to once or twice a month October through March. Water young trees that are not established and evergreens twice monthly if possible. A tree takes one year for caliper inch of trunk diameter to establish. If you planted a two-inch tree, you will need to provide extra supplemental water for two years until it can get established.

Most tree roots extend two to four times the diameter of the tree’s crown. A storm that produces one inch of rain provides a little less than 2/3 of a gallon per square foot. A tree with a crown diameter of four feet would have a root system roughly between eight and sixteen feet. If this tree has a 12-foot root system, it would receive about 67 gallons of water with one inch of rain. Keep in mind that one inch of snow does not equal one inch of rain! According to NOAA, on average, thirteen inches of snow equals one inch of rain.

Lack of moisture in the months of October through March can cause damage to the root system of plants which then affects their overall health. Drought stress will begin to appear in late spring and summer when the temperatures begin to rise and precipitation amounts decrease. Stressed plants are also more susceptible to disease and insects.

Make sure that you water on days where the low temperatures will stay above freezing and the daytime temperatures are above 40 degrees. Water earlier in the day so the water has a chance to soak in to the ground before temperatures decrease at night. Disperse the water evenly around the whole tree underneath the canopy and roughly three feet from the trunk.

Your shrubs will also need extra water! A small established shrub that is less than three feet needs five gallons every month from October through March. A large established shrub that is more than six feet needs 18 gallons monthly. Newly planted shrubs require the same amount of water twice a month. Mulching is also a great way to retain moisture around your plants! Keep in mind that if it is dry, your turf will need to be watered as well!

Check out these resources for more information:

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