KENNEWICK -- Not long ago, one of my sons noted that I was an optimist who tends to look on the bright side of things.
Not always. Lately, I've been downright grumpy about our spring weather.
Just when I think spring has arrived and it's safe to plant tender annual flowers and vegetables, freezing nighttime temperatures loom in the forecast. Plus, there's the wind. Even if frost doesn't get your plants, the ever present wind can do just as much damage.
I have been trying to wait patiently, noting that the last average date of frost is between May 1 and 15, but it's an average. As I write this column, no frosty nights are predicted, but nighttime temperatures still are below 50 degrees. That's pretty chilly for warm-season plants. The curmudgeon in me worries that it might not be truly safe to plant until late in May.
On the positive side, I have had more time to look around the yard and tend to other plants. Earlier inspections revealed significant dieback on some shrubs due to winter injury. I pruned them sparingly and have been waiting to see the complete extent of the injury. The latest examination of my roses and a few other shrubs revealed additional dead wood that should be pruned out. The good news is that a few shrubs that I thought had succumbed are sprouting at the base. I can feel some of my optimism returning.
I'm certainly not the only local gardener to lose plants from winter injury. I talked about winter burn damage earlier in the season, but now entire plants are suddenly turning brown. A number of cedars in local landscapes seem particularly hard hit. That's not surprising, as some cedars aren't extremely cold hardy.
Deodar or Himalayan cedar (Cedrus deodara) and blue atlas cedar (Cedrus atlantica f. glauca) are prone to injury from cold winter temperatures. The blue atlas cedar supposedly is hardy in Zone 6, which includes most of our local region and should be able to endure temperatures down to minus-10 degrees. However, it is fairly common for atlas cedar to be injured by sub-zero temperatures only down to minus-5 degrees. The Deodar cedar is more tender, rated for Zones 7-9, where temperatures don't go below zero.
Both these cedars will suffer damage from severe cold temperatures, but why hasn't this damage shown up after other recent winters when we experienced temperatures just as cold as this past year? Timing is the most likely factor. Our first period of severely cold weather happened abruptly after relatively mild late fall weather. The cedars, and other landscape plants with significant dieback, were subjected to injury because they weren't completely physiologically ready or "acclimated" for the extreme cold temperatures more typically experienced in mid-winter, not in late fall.
Other factors involved in cold temperature damage involve the severity of the temperatures, the length of the cold spell, the health of the plant, the occurrence of fluctuations between mild and cold weather, the plant's location and the genetically determined winter hardiness of the plant.
Signs of cold temperature injury most likely will continue to keep showing up over the next couple of months, especially when hot weather arrives and puts additional demands on the injured plants.
On the bright side, the loss of a tree, shrub or perennial gives you a chance try something new. I guess I am an optimist after all!
* Marianne C. Ophardt is a horticulturist for the Washington State University Benton County Extension.