Gardening in a changing climate

Jill Severn portrait

For the first time in over a decade, the U. S. Department of Agriculture has changed the “plant hardiness zones” that gardeners, farmers, and nurseries rely on to choose what we grow and what plants we buy. This map is based on the past, and does not predict the future. It’s author says the biggest changes in the past decade have taken place in and near Arkansas, Kentucky, Missouri and Tennessee, where temperatures have risen by as much as five degrees.

Our area has been classified as Zone 9, or maybe 8 – sometimes it’s hard to tell the difference between the two shades of color that delineate the zones. And our classification hasn’t changed – yet. That’s because the hardiness zones are based on a single metric: minimum winter temperature. That’s useful for telling us when a perennial or newly planted shrub might freeze to death, but it’s silent on how much hot sun or drought plants can take in summer. That’s the metric most likely to be on our minds.

Still, the Thurston County Department of Emergency Management, which pays close attention to climate forecasts, reports that our winter lows may actually go lower in the future, though, this being a holiday week, they could not provide a quick answer to what makes them think so. But there are plenty of references that predict we will have more days of heavy rain in the winter and possibly the spring and fall, giving us about the same annual average rainfall.

Good news for local gardeners

The good news for local gardeners is that we will have a longer growing season – that is, more days without frost or freezing temperatures. The bad news we already know: we will need to adapt to longer, hotter, drier summers.

To do this, some friends are already buying seeds from California catalogues, and planting sweet potatoes and other crops that may thrive in our longer, warmer growing season. It’s a good bet that local nurseries will also expand their stock of heat-tolerant, long-season offerings, including seeds or started plants of cantaloupe and maybe even small watermelons.

A Seattle man is thinking even bigger: He’s importing and planting California redwoods.

Here, to accompany your leftover turkey sandwich, is a sampling of California resources and seed catalogues:

• First and most informative is Renee’s Garden. Renee, reached by phone as she was making cranberry sauce, reminded me that being located in California does not mean all the seeds they sell come from that state. She also noted that her garden, located at the edge of a redwood forest, is in a completely different climate than the coast, which she can reach in less than half an hour.
• Annie’s annuals also includes perennials, and lots of California native plants. She offers a free mailed catalogue, which makes wonderful bedtime reading.
• A PBS listing of California seed companies includes one that’s now decamped to Salt Lake City, Utah called True Leaf Market, which has acquired several smaller nurseries, including one that specializes in a large selection of Asian vegetables.
• Bakers Creek Seed Company specializes in rare heirloom seeds. They have some wildly purple tomatoes, and an impressive variety of native and exotic plants, including, for instance, about a dozen varieties of amaranth. Their 500-page catalogue sells for $14.95. That might be enough bedtime reading for a whole winter.
• If tomatoes are your passion, you’ll also want to check out TomatoFest, which carries 650 varieties of heirloom, open-pollinated tomatoes.

If this list isn’t enough to keep you in bedtime reading, there’s always Auntie Google, but public health experts tell us it’s bad for us to be online at bedtime. That’s why we need real seed catalogues. A case in point, White Flower Farm, publishes the Cadillac of garden catalogues, which they will send you for free. Sweet dreams are guaranteed.