What Has Winter Brought?

By BILL CARAS

What has winter brought? For Montana gardeners, “What will spring bring?” might be the better question. Either way, the answers vary every year. What will survive unscathed? What might be winter injured or even killed outright?

In spring 2010 the answer was a resounding “Heck yeah, a lot of plants were winter killed!” The hard (<10 degrees) freeze in early October of 2009 was the culprit and the damage was widespread.

Interestingly, most of the plants that died were capable of withstanding much lower temperatures but had not achieved full dormancy when the cold struck. This was evidenced by the fact that leaves turned brown and hung on the plants all winter. Some fully mature trees were actually killed but the highest mortality numbers were in flowering shrubs such as roses, caryopteris (blue mist spirea), and lavender.

So, what will the spring of 2011 bring? All signs point to much better survivability. Fall 2010 had a steady progression of colder temperatures and the first few frosts were mild, gently notifying outdoor plants it was time to transition to dormancy.

Additionally, snow has blanketed the ground continuously since mid-November, which insulates roots that are often more freeze injury-prone than their above-ground counterparts. Hence, I predict people will see their neighbors’ thriving hybrid tea roses, butterfly bushes, and Japanese maples and conclude they are perfectly hardy for western Montana. Indeed, they may enjoy them for years until we have an exceptionally harsh winter or freakish weatherevent.

The bottom line is this: Here in Missoula we consider ourselves to be in zone four. But, all that means is a low winter temperature range between -20 and -30 degrees Fahrenheit, which we seldom see these days.

We are more accurately in zone five, which translates to -10 to -20 degrees F. Zones, however, are artificial human inventions and, not surprisingly, do not take into consideration factors such as soil types, humidity, and, as we have recently learned, timing of weather events.

This is the dance we western Montana gardeners do every year. The rewards can be great and the challenges are… Fun!

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Bill Caras is a lifelong Missoulian whose family has been here over a century.  The family business, Caras Nursery and Landscape, has operated from the same location on S. 3rd W. since 1896. Bill is a plant nut and draws from many years observation of all things related to gardening in western Montana. Still, he says, he learns something new everyday.