How to protect your plants from freezing weather

By Todd Merrin and Bruce Gaudette | Dec 28, 2011

Frost on rooftops and frozen puddles in the morning tells us that winter has arrived!  

In fact, meteorologist Heather Buchman ( predicts frequent winter storms, with wild temperature swings and wet weather early in the winter season. ( predicts freezing weather through January and February, and into early March.  

Protect your plants from frost and prolonged winter weather that is expected to stay for a while.  These helpful tips will help you beat the winter gardener’s blues:

When you landscape your yard, try to use plants that will be durable during the four seasons of the year.  Here in the Seattle metro region, we are generally in USDA zones 7 and 8.

You should always choose plants that are winter hardy to zone 7, or to zone 6 for extra protection.  Even with this planning ahead, you still need to take some protective measures to protect your plants in the winter.

The most important thing that you can do for your plants in the winter is to pay attention to severe weather forecasts.

Mulching is one of the best ways to protect plant roots. Bark, straw, sawdust, peat moss, leaves and even grass clippings are the most common mulching materials. Remove the weeds (if possible) before applying the mulch. As a rule, the mulch should be about 2 inches in depth.

Keep the mulch an inch or two away from the trunk or main stem of the trees and shrubs. For roses and cane berries, you should mound the mulch over the canes.

Then when spring arrives, after all danger of frost has passed, pull these mulching materials away from your plants and spread them around the garden bed.

Check through the mulch about once a month to be sure that moisture is getting to the soil below. This is especially important for plants that are situated under the eaves of the house or under tall evergreens where the soil is likely to dry out.

It is important to note that the combination of dry soil and cold temperatures can cause serious freeze damage to garden trees and shrubs. In fact, you may need to water dry areas of your garden from mid-December through mid-March, if you find the soil dry.

Beware of clear, starry nights.  Clouds act as an insulator against heat loss, but in cloudless nights, plants lose the heat they stored during the day and don’t benefit from any natural insulation.

Water freezes under cold weather conditions and so does the soil, meaning that plant roots can’t get moisture.  

Furthermore, the water in their cells also freezes and damages the cell wall.  Then plants defrost in the morning and their cell walls can fatally rupture.  Tell-tale signs of a frost-damaged plant are limpness, distortion and blackened, translucent leaves.

Cold air sinks and warm air rises, so if there are any low-lying areas in your garden they could be affected by frost while the rest of the garden is not.  Slopes are also usually frost-free, as are sheltered areas, such as under large trees, or against walls.

Plant any tender species in protected sites.  On cold nights, cover them with a tent made of plastic sheeting in a wire frame.  The tent should be close to the plants; otherwise the heat around the plant will evaporate.  Remove the tent in the morning.

If your plants do suffer frost damage, there is still hope.  Don’t cut off the damaged parts during the winter.  Most plants will recover by springtime and the pruning, along with some balanced fertilizer, will encourage healthy new growth.  

Until then, stay warm out there, our fellow cold weather gardeners!

Bruce Gaudette, owner of Land Hoe! Landscape Design and Construction, holds an Associate Degree in Horticulture from Edmonds Community College and industry certifications in paver and permeable paver installation.  Todd Merrin, designer for Land Hoe!, holds a degree in Landscape Architecture from California Polytechnic State University, San Luis Obispo.
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