Hardy hubris: Pacific Northwest winters test gardeners’ climate optimism

By Trevor Cameron / The Golfing Gardener

Editor’s Note: This column is provided by Sunnyside Nursery in Marysville in place of the weekly Whistling Gardener column by Steve Smith, who is taking the week off.

This time of year presents the perfect opportunity to discuss plant hardiness and perceptions of our climate’s growing zone. Following our recent cold spell, it may be time to assess some damage in many local landscapes, including my own. The majority of us gardeners are confident (if not cocky on occasion) that we can grow just about anything in our Pacific Northwest maritime climate, then Mother Nature steps in to remind us who is in control.

I think the vast majority of folks utilize the internet — news flash, right? One can simply type in their zip code and website after website claims our USDA climate hardiness zone is Zone 8. This equates to minimum temperatures over winter in the 10- to 20-degree range. Last week, we got down into the low teens, which is often the case at some point over a typical winter. There are microclimates everywhere in our region, so some folks will be a bit warmer (right on the water for example) while others are even colder. Simple frost is not the problem; it’s prolonged deep freezes that are more concerning, after which we tend to lose specimens in the landscape entirely or what is left after pruning out dieback come spring is not worth keeping.

I can only speak on things I have tried, in addition to the trials and tribulations I hear from the nursery’s patrons. Zone 8 is simply not reliably hardy, if you ask this gardener. Gardening is ultimately an experiment in trial and error — either you learn your own lessons as you go or you learn from fellow gardeners that have had similar experiences in the past. Evergreen shrubs, such as pittosporum, bottlebrush (callistemon), “hardy” olives (olea sp.), the vast majority of hebe cultivars, grevillea, loropetalum (fringeflower), pineapple guava (feijoa) and other Zone 8 material will, at best, have some foliage damage after a freeze like earlier this month. Sometimes they will make it through, often after a spring prune, some fertilizer and a prayer or two. All cool plants for sure, but you will need to answer the question for yourself: Is it worth the risk to try?

A newer term we now use is “temperennial” — perennials that are right on the Zone 8 hardy line. A few worth mentioning are any Spanish-type lavenders, some varieties of salvia and some cultivars of “hardy” fuchsia. To me, plants like these produce an easy answer: treat them as annuals and feel fortunate if they come back. Spanish lavender is often hardy to Zone 7, but it presents another zone issue for us: winter wet and drainage. They like dry conditions and even if it is not too cold, it is often just too wet for them over our winters. Salvias are supreme hummingbird magnets (I use them every year), simply treat them as the blooming machine annuals that they are. There are plenty of truly hardy fuchsias, but some of the coolest colors are Zone 8. Choose a wiser flavor or, again, treat them as an annual that will offer you months of color and pollinator action through the summer and fall. One quick tip for both salvias and fuchsias: If you are trying to keep these going year to year, never cut them back in fall or winter — wait until spring (April) to see where new growth pops out on the old wood and then cut them back to those points.

I am hoping we can agree on two things: You cannot cheat Mother Nature, and it is better to be safe than sorry. Curb your own zone denial by considering your plant options ahead of time and learning from gardeners, like me, who have lost far too many Zone 8 plant specimens over the years. Think about what you already have outdoors and what may need a little protection, then stop into your favorite garden center to talk with a professional about options that may help keep these plants safe. Using USDA Zone 7, and lower, plant options is a safer choice, and trust me, there are plenty of spectacular plant options to catch your fancy.

Free class

Sunnyside Nursery in Marysville will host “PNW Fruit Trees” at 10 a.m. on Saturday, Jan. 27. For more information, go to www.sunnysidenursery.net/classes.

Trevor Cameron is a certified professional horticulturist (CPH) and serves as general manager for Sunnyside Nursery in Marysville. He can be reached at sunnysidenursery@msn.com.