Get Growing: Weatherproof your garden this year

You may have noticed a certain manic quality to the weather in recent years. The rules of Seattle gardening used to be weird, but simple. It was dry in summer, wet and cool (but not freezing) from fall through spring. Looking at recent events, that rulebook seems to have been composted. In 2021, there was an atypical drought from January through April before the growing season got going, followed by the infamous summer “heat dome” and then two harsh winter freeze events leading into spring of 2022. Many gardeners’ treasured plants died from this triple threat of stressors, others lost half their growth.

Here in the Pacific Northwest, we’ve been fairly spoiled as gardeners. Our mild, mostly frost-free climate has allowed us to grow exotic wonders like windmill palms and bananas, Chilean fire bushes, dahlias, hardy fuchsias and more even without any particular winter protection. It’s time to reevaluate our growing conditions.  If we can assume anything, it’s to assume nothing and be ready for everything.

A couple of years ago, folks started looking for “drought-tolerant” or “xeric” plants to combat the extra heat we were facing, but now we are seeing many other factors at play besides heat. I was surfing the line of keeping my echinaceas and dahlias happy through our wet winters by planting in my sandiest soil in the sunniest spots, but this year’s winter was much longer, colder, and wetter than usual.

Choose wisely

So how can we choose plants now? One way is wandering and taking note of what’s working. Which plants came through this year unscathed? A good place to start is with public-facing gardens like shopping malls, hotels and restaurants, who have paid experts to choose resilient, tough customers that need little pampering.

Botanical gardens are great for ideas too, but remember those plants are getting spa treatment from the staff.

Get out in nature for native inspiration to see which groundcovers, grasses, perennials and shrubs bounced back just fine. This spring I added a Ribes sanguineum (red flowering currant) and some Tellima grandiflora (fringecups), which thrive at woodland edges in places like Golden Gardens and Green Lake where they get no supplemental water, offer early blooms and feed pollinators in the off-season too.

Some of the winning plants will be the stalwarts you see in parking lots and foundation plantings, like Viburnum davidii, marigolds and geraniums, which, while not as thrilling as the newest Grevillea or Abutilon on the nursery shelves, have the benefit of a comforting level of permanence. Viburnum davidii makes a great base for a planting with its crinkled dark blue-green leaves. A Mugo pine could be a nice alternative. Add some wispy gold Carex and maybe a red Heuchera and you have year-round color that is drought-tolerant once established.  

You can check out a living laboratory at the Center for Urban Horticulture, which is conducting the Climate-Ready Plants Project along with five other Western universities. The trial bed, entering its second of three years, is in the grassy field south of Merrill Hall. The project is evaluating which plants do best under a low-water regime. The first year, all the plants were watered well to help them get established. Beginning this year, the plants will be tested under three different irrigation programs.

Steps to a resilient garden

Build your garden with a structure of stalwarts that will carry on without extreme measures.  Then decide on your risk-tolerance. I decided, for instance, that I could in fact live without trucking my lemon tree in and out all year and watching its leaves drop after each move. If there’s a plant you can’t be without, find out how to keep it happy. Research what conditions the plant prefers in its native home, from soil to temperatures. 

Choose plants that suit your conditions, as best as you can figure them. Group plants with similar needs together so you don’t need to water the entire yard for a couple of thirsty plants. In the ground, irrigation systems or soaker hoses can help offset drought. Covering the ground layer with plants or annual applications of mulch will help retain moisture and regulate temperature. A key feature of efficient Piet Oudolf-style “matrix plantings” are masses of mat-forming sedges or groundcover plants.

Another tip is to buy smaller plants or plugs if you can find them, which will establish faster, and be more adaptable to changing conditions, as well as extending your plant budget.

When it comes to preparing for winter, mulch is your friend here as well, keeping the ground toastier. If a frost is expected, water thoroughly.

If you haven’t seen the rain in a week — in any time of year — water. For plants in pots, especially marginally hardy ones, consider moving under shelter against a building, wrapping in frost cloth, or a wire cage filled with shredded leaves. Porous fabrics are best for wrapping as they’ll let in light, air and water.

Then, cross your fingers, and be ready. Gardening is never static — and each change opens up the chance for a new garden.