KP Gardens

Compliments to the Cold Weather Garden, Our Frosty Frenemy

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There’s much to be admired about our winter landscapes here in Western Washington. The way the beaked hazelnut catkins dangle like beaded tassels on ritzy flapper dresses. How the various varieties of moss cling to the rocky embankments along roadsides and drape like scarves over dormant limbs, reanimated and relishing the abundance of cool moisture. Even the drifts of toasted bracken fern make an impression as their skeletons reflect amber and gold upon encountering the rays of a low-lying sun. It’s a vision as splendid as it is subtle.

Before we know it, the not-so-subtle embellishments of spring will begin vying for our attention. In the garden, snowdrops, crocus, hellebores and hardy cyclamen will break through the grip of frigid ground, accompanied from above by blooms adorning the scaffolding of camellias, witch hazel and daphne. Daffodils, fruit blossoms and tulips patiently lay in wait for their moment to burst forth to join the ensemble. It’s a finely choreographed dance and everyone knows their part. Timing is everything.

To me, it’s endlessly fascinating that these plants know when to awake from their slumber. They count the hours of light and dark, warm and cold. A survival strategy ingrained in both their cells and their perspective pollinators. It’s the manifestation of a quiet communication between Earth and cosmos. And all of it begins to unfold no sooner than the worst of our winter weather seems to happen. Or at the very least when it becomes most manic. Chances for deep freezes and snow increase in the latter half of the winter season, almost like Jack Frost forgets we exist until the last minute and is forced to play catch-up before the equinox.

From our perspective, this can be torturous. While plants undergo their seemingly disciplined unfurling, the first warm(ish) sunny day of February never fails to whip us into a frenzy, causing many to storm the nearest garden center eager to obtain flats of blooming pansies and primroses. Or better yet, plant out rows of freshly delivered stocks of cool season crops from catalog shopping sprees. As if needing to rent a jackhammer to get them into the ground isn’t enough indication that perhaps we’re still a few weeks out from achieving “workable soil.”

Seasonal restlessness aside, from an economic, agricultural and general joy perspective, and considering that many of our favorite fruits and flowers require a certain number of “chill hours” to bloom, the last vestiges of winter’s icy grip are crucial to summoning forth what makes spring and autumn bountiful.

Vernalization (Latin for “belonging to spring”), the process to which “chill hours” refers, is the time that temperatures need to remain between 32 and 45 degrees Fahrenheit for most of our fruit trees, flower bulbs and some semi-herbaceous perennials to break dormancy, produce flowers and form seeds and/or fruit. Hours of sunlight, or photoperiod, also play a role in when some plants and trees break dormancy, though chill hours are the primary benchmark for most of the early spring bloomers.

Apple trees need between 700 and 1,200 chill hours, or the equivalent of 29 to 50 full days. Blueberries need 500 to 550 hours. And grapes, peaches, plums, blackberries, figs and strawberries are all part of this cohort. As for our spring bulbs, most need a minimum of 12 weeks, with tulips requiring up to a whopping 16.

Similar to vernalization is the process of “stratification,” often referenced on seed packets, typically for bi-annuals and wildflowers. It’s recommended that these seeds are sown in the fall because they need a period of cold and wet to break dormancy, primarily because the protective husk surrounding the seed needs to soften so it can germinate when warm weather arrives.

However, if you missed the fall deadline, it’s easy to manufacture the cold period experience by keeping these seeds in a fridge for a few weeks inside a zip-lock bag of moist soil medium or on a damp paper towel. Gardeners in warm climates also use the fridge method for their spring bulbs since the winter temperatures aren’t cold enough to meet chill hour requirements.

Western Washington averages 1,200 to 1,400 chill hours per year. Doing the math on what we’ve accumulated so far isn’t quite how I want to be spending my weekend. But right now the forecast looks promising; February will be cold and March slightly less cold. Plenty of rain, maybe some snow.

While winter is beautiful in its own way, it can certainly feel drawn out as we near the end, and knowing how important cold weather is to our spring plants doesn’t necessarily make it any more appealing. That’s just the way our winters are though, and nowadays I think there’s much to appreciate about a season that unfolds with some regularity.

Around the solstice in December, I observed some anomalous blooms out of sync with the rest of the garden, leading me to wonder what seasonal oddities can be expected as the climate shifts into a new era. We can’t know what Mr. Frost has left in store for us, but for now, I regard the tight spears of bulb buds popping up as subtle green beacons of perseverance. I sense there’s still some normalcy left to look forward to.


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