Winter Watering

The calendar reminds us that cold and snow will eventually arrive, so
gardeners should turn their minds to helping trees prepare for dormancy.

Carol O'Meara, Colorado State University Extension

Carol O’Meara, Colorado State University Extension

LONGMONT –  I’ve reached the stage in life where I miss the good old days, randomly blurting out grumpy declarations of fond memories of when things were better than now. I harken back at least five years, when September didn’t have week after week of 90-degree weather. Then I stomp off muttering, mumbling, and wondering where I left my glasses.

A quick search of weather history tells me that September isn’t immune to extreme warmth; we’ve had spikes into the 90s and 2000 and 2001 had several days registering those temps. We’ve just been enjoying several weeks of the heat.

But the calendar reminds us that cold and snow will eventually arrive, so gardeners should turn their minds to helping trees prepare for dormancy. Part of that is reducing water, slowly, to trees and shrubs to help them harden off. This doesn’t mean stop watering entirely; roots need moisture to remain healthy. Slow down your frequency but don’t entirely stop.

Predictions of little rain and snow means it’s time for gardeners to make plans for winter watering trees. Overly dry soil conditions kill off tender feeder roots, which are responsible for taking up water and nutrients that support the tree. The effects of this show up throughout the year as leaf scorch, twig dieback, poor leaf size, iron chlorosis, or stunting of the tree. Insects and disease become bigger problems for stressed trees.

To get them ready for dormancy, water trees thoroughly in fall after their leaves drop to ensure they go into the winter with moist soil.  Researchers at Colorado State University recommend that all landscape areas should be watered thoroughly in late fall, then once monthly until spring.

But finding time to drag around hoses is tough at this time of year and getting your feet wet on a chilly day is about as attractive as a root canal. What gardeners need is good planning to take the chore out of winter watering.


Water once per month through March if we don’t get an inch of water through snow or rain.

Make it easy: Measure snowfall at your house with a ruler; don’t rely on total accumulation listed in the news.  Write each storm’s amount on your calendar and add it up every four weeks. If it’s less than 12 inches of snow, it’s time to water.


Warm days when temperatures are above 40 are best for watering.  Choose days when no snow is on the ground and the soil isn’t frozen. Water should be trickled slowly into the soil.

Make it easy: Coil a soaker hose so that it spirals out from around the tree and leave it there for use over the next few months. Long hoses can be used to water several trees of the same size at the same time. Have an inexpensive timer on the faucet automatically shut off the hoses, or set timers in the house to remind you to turn off water.


The dripline of the tree is the best place to water, which is the area directly under the tips of the branches. The place to soak is two to three feet on either side of the dripline, to a depth of 12 inches. But many tree roots extend well beyond the canopy, especially more mature trees.

Tip for success: Soil needles work best if the ground is soft, and be sure to insert it only eight inches deep. The roots taking up water are shallow, in the top
12 inches of the soil.

How much

Researchers are still working on this, but a good rule of thumb is to give your trees 10 gallons of water per diameter inch of trunk for them to survive.

By Carol O’Meara. Colorado State University Extension, together with Boulder County Parks and Open Space, provides unbiased, research-based information about consumer and family issues, horticulture, natural resources, agriculture and 4-H youth development. For more information contact Colorado State University Extension at the Boulder County Fairgrounds, 9595 Nelson Rd., Box B, Longmont, 303.678.6238, e-mail or