Extension

It looks like cold weather is starting to settle in, and those sharp north winds are a keen reminder that it is wintertime. While many gardening chores have a brief hiatus, irrigating the landscape is essential year-round.

 

Soil moisture is a critical factor in preventing winter damage to many landscape plants. Dry soil and harsh, winter winds can be a deadly combination for landscape plants. These conditions make plants vulnerable to desiccation and root damage. All plants require moisture throughout the winter, but narrowleaf and broadleaf evergreens have the greatest need for it.

 

If there has been no precipitation for more than a month, the soil is dry, and daytime temperatures are mild, then consider irrigating the landscape, especially when dry cold fronts are in the forecast. It’s essential to water the landscape at least 24 hours in advance. Applying about a half-inch of water ahead of the front allows sunlight to warm the moistened soil. Irrigation will help protect roots from extreme temperature swings.

 

Keep in mind that moisture must be available below the freeze line. When soil freezes without enough moisture in its pore spaces, moisture is drawn from the plant roots and forms ice crystals. This leads to desiccation, root injury and what many homeowners call winter kill.

 

However, too much moisture can also be a problem. Cold, saturated soils can cause root rot. In addition, excess moisture encourages winter weeds to germinate. Generally, watering every three to four weeks throughout a dry winter is adequate. Gardeners want to moisten the top 6 inches of the soil.

 

Sprinklers should never run during a hard freeze. Moisture build-up on plants can freeze, causing significant damage. Additionally, icy conditions on sidewalks, driveways, and streets pose a hazard to both pedestrians and motorists. For those with an irrigation system, use common sense. Water can freeze in the system, splitting the pipes and leaving homeowners with expensive repairs.

 

Potted plants located under the eaves of a home or next to a storage shed may be sheltered from rainfall. It’s vital to keep these plants supplied with moisture throughout the season.

 

OSU Extension offers additional winter-watering information in fact sheet HLA-6404 Winter protection for landscape plants.