Tuesday, November 30, 2010

Fall and Winter Watering by Donna Duffy

We are on track for one of the warmer autumns on record. In addition, we know that Colorado winters can have long spells of dry, warm and windy weather. During the cold weather seasons, pay special attention to weather and soil conditions and provide supplemental water to keep the root systems of trees, shrubs, lawns and perennials alive and healthy. Here are some tips to help them survive the winter.

General Tips
Apply water in mid-day when the air and soil temperatures are above 40°F and there is no snow cover. If the root systems don’t receive adequate water, the plants could appear normal in the spring, but may be weakened and die off in the summer when temperatures rise. Lack of winter water may also create insect and disease problems. Whenever you water, remember to disconnect the hose when you are finished!

Newly planted trees are most susceptible to winter drought injury. All trees utilize water most effectively when it is allowed to soak into the soil to a depth of 12”. Whether you use a sprinkler, deep root watering device or soaker hose, be sure to apply water to many different locations below the tree and beyond the canopy of branches. Trees need 10 gallons of water for every inch of trunk diameter (measured at knee height). If you use a deep root needle, insert it only 6-8” below the ground – if it’s deeper than that, it’s out of reach of the tree roots.

Even established shrubs will benefit from winter watering in dry years. Apply five gallons of water for small shrubs (less than 3’) and 18 gallons for larger shrubs. If the shrubs are newly planted, water twice monthly. Mulching the shrubs will help them retain moisture.

Roses and Other Perennials
If you planted perennials in the fall, they probably didn’t have much time to establish a strong root system and they will need winter water. Water when the ground appears dry by checking the soil condition 2-3” deep.  All perennials that are in a windy or southwest location will benefit from supplemental water. Keep an eye on the mulch around your perennials, it’s often blown around in the winter and will need to be put back in place or supplemented.

Lawns can suffer winter damage as well as trees, shrubs and perennials, especially newly established lawns. These new lawns will need supplemental winter irrigation following the general tips above. During dry winters, lawns are more susceptible to winter grass mites and dessication if occasional winter irrigation is not applied.