With the snow and sub-freezing temperatures, we found that it’s difficult to predict which landscape plants may have been damaged or even killed at this point.

Winter injury problems will begin to manifest themselves slowly over the coming weeks, even into summer. Don’t be in a hurry to decide that a plant is dead. Be patient. Symptoms of damage may take months to show up.

A plant may appear dead in spring, but then sprout up from the roots later. Conversely, a plant may seem to be doing fine until a spell of really hot weather puts stress on the roots that were partially injured.

If a plant has been injured, be sure it gets proper watering during summer even if it is normally a drought tolerant plant. Even plants adapted to dry summers will need water when recovering from freeze damage. You might have to water plants that are under the eaves of your house.

Climates in our area differ. Skagit County is considered USDA Zone 8-A, which only considers average low temperature. There are many other factors that affect a plant’s ability to thrive.

There are microclimates that are produced by location and exposure, wind, rainfall, drainage, proximity to marine water, walls, or other protection. These affect cold hardiness.

The genetic makeup of a plant that will affect its response to cold is called ‘hardiness.’ Pines and junipers are examples of plants that endure hard freezes with no trouble, but shrubs such as Daphne or Escallonia can suffer.

It is better to select plants that the plant tag states are hardy to Zone 7. “Zone denial” could bring some sadness, though many gardeners are willing to take the chance.

Certain parts of plants freeze more readily than others. You will see buds damaged more often than stems. Loss of spring flowering is a common symptom of freeze damage; your rhododendrons are often affected this way.

The brown buds may be totally or only partially frozen. Partially frozen ones might flower but be disfigured; there is always next year. On the other hand, many plants need winter cold to flower and produce fruit. Peaches, lilacs, peonies and some varieties of apples are local examples.

Roots, when insulated by the ground around your plants, should survive just fine. But roots exposed to freezing air while in a container are at risk; roots systems don’t recover from being frozen.

Plants in containers are especially prone to being killed in hard freezes. This even applies to plants such as pines that are normally hardy when planted in the ground. It’s best to bring your containers into your garage (which does not have to be heated). Terracotta containers absorb water and may crack when the soil freezes.

Shallow root systems are more vulnerable than deep, established root systems. You may need to add additional mulch to protect them. Graft unions are sensitive to cold injury and may need extra protection such as mulch or wrapping; remove these when the weather begins to warm up.

When deciding if a plant has died, wait awhile. Don’t be in a hurry to dig it out. Check for live wood by gently scraping a tiny section of the bark with a knife or your fingernail.

Dead cambium tissue is brown or even soggy, while live tissue will appear white or green. Start at the outer branch tips and work your way toward the trunk. Many times, younger twigs may be dead, but older wood remains alive.

You can prune off all dead tissue at any time; prune off broken limbs to where they were attached to a larger branch or trunk to make a clean cut so the shrub or tree can heal properly.

There is other winter injury with which you may have to contend: desiccating winds that dry plants out, or chemical damage from salt or chemical deicers. Salt runoff that accumulates in the soil can be toxic, eventually killing plants.

Salt on leaves may cause disfiguration. Snowplows or snow blowers may bury plants and cause limb damage. Heavy, wet snow may bend branches to the breaking point.

You may want to wrap your tall hedge plants in plastic deer fencing to keep their branches upright. Animals feeding, such as deer eating everything they can reach or voles eating bark under your mulch, can also cause permanent damage.

Native plant species tend to be hardier than non-native species if grown in their natural habitat. Plants that are well established will do better than newly planted ones.

Healthier plants can withstand bad weather better than those stressed from drought, insects, fertilizer put on in the late fall, or those living in a poorly drained area. Standing water can suffocate roots.

Most of the time your plants will survive. Sometimes a large plant or tree is permanently injured but has enough reserves to appear to live on for a year, or even several years.

Keep notes and if some of your plants seem to struggle, consider replacing them with plants more suited to your area.

Landscapes are ever changing, and you can work with that to make your garden thrive. And if you want to do something in your garden right now, go out and prune the deadwood from your shrubs.

— Diana Wisen is a WSU/Skagit County master gardener. Questions about home gardening or becoming a master gardener, may be directed to: WSU Extension Office, 11768 Westar Lane, Suite A, Burlington, WA 98233; by phone: 360-428-4270; or via the website: www.skagit.wsu.edu/mg.

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