Words and Photos By Grace Hensley

Piet Oudolf-designed perennial meadow at Scampston Hall in North Yorkshire UK utilizes Phlomis russeliana mixed with hardy pink Geranium ‘Ann Folkard’, blue Amsonia, and stout balls of Alliums and Nectaroscordum

At first glance, the Pacific Northwest doesn't seem like a region where gardeners would need to worry about drought. Seattle averages nearly 40 inches of rain each year—almost twice as much as Essex, UK where plantswoman Beth Chatto built her renown gravel garden out of the carpark. But designers working in the Puget Sound region know that this statistic hides a difficult truth: most of that rainfall arrives between November and April. From May to October, our gardens are on their own.

As the climate changes, this seasonal dryness is becoming more extreme. According to modeling by the Seattle Climate Vulnerability Assessment, average summer temperatures in Seattle are projected to increase by nearly 5°F by 2050, and rainfall in July and August could decrease by about 15%. This means the already dry summer months will become even hotter and drier—more like Northern California than the temperate Seattle we remember.

To design gardens that survive and thrive under these conditions, landscape professionals must rethink both their plant palettes and their approach to client education.

What Climate Change Really Means for Designers

The Hardy Plant Society’s 2025 Study Weekend in Portland focused on “Nimble Gardening in an Evolving World.” Speakers with experience in drought-adapted climates like Southern Australia, California, and Greece emphasized that success will require a shift from rigid design rules to flexible, responsive practices.

Author Giacomo Guzzon (“Visionary: Gardens and Landscapes for our Future”) noted that by 2050, Seattle's climate may resemble San Francisco, while Portland could feel more like San Antonio, Texas. That’s a dramatic shift, especially when you consider the implications for winter chill, precipitation patterns, and plant stress tolerance.

But this isn’t just about weather. It's about the unpredictability of that weather: early-season heat waves, late-season drought, and prolonged dry spells interrupted by sudden downpours. These swings are hard on plants—and clients.

Client Expectations vs. Climate Reality

Many clients are aware that climate change is real, but they often misinterpret what that means for their own yards. They may say they want a “climate-resilient” or “drought-tolerant” garden, but still expect bright color, constant bloom, and full green foliage from May through September.

Others come in asking for a “native garden,” without understanding that many Pacific Northwest natives evolved in forested, moist environments—not open, dry, south-facing city lots. As you know, vine maple (Acer circinatum) or red flowering currant (Ribes sanguineum) might thrive at the edge of a Douglas fir grove, but not in a reflective gravel courtyard.

To bridge this gap, designers must take time to educate clients about how aesthetics, function, and survival intersect. Explain that many drought-adapted plants will enter a natural summer dormancy, pausing growth and delaying bloom. Many plants from New Zealand, for example, tend to have vivid brown foliage. Others will have small, silver, or fuzzy leaves that reflect light and conserve water—beautiful, but different from the lush look of traditional perennials and English Garden borders.

Left: This Denver Botanic Garden vignette relies on Eryngium Blue Glitter with Stipa tenuissima and Festuca glauca foliage for color. Right: Pale yellow Sisyrinchium striatum, native to Chile, paired with Phlomis russeliana for early summer color.

Don’t Say “Mediterranean”—Say “Summer-Dry”

Historically, designers turn to “Mediterranean” plant palettes—lavenders, rockroses, rosemary—to deal with water restrictions. Designer Sue Goetz relies on these stalwarts and loves to include the common garden sages, salvias, and the stately varieties of Phlomis. All of these plants rely on leaf color and texture for their design impact with pops of color to delight our summer-loving clients. The term “Mediterranean” often misleads clients into expecting bright color, year-round flowers, and lush growth with little care.

Instead, focus on plants from “summer-dry” bioregions—places that experience wet winters and dry summers, regardless of latitude. This includes:

Southern and coastal Oregon
California coastal chaparral and foothill zones
Central Chile
South Africa’s Cape region
Parts of Southern Australia

Look for plants adapted to these rainfall patterns and tolerant of winter moisture. Not every dryland plant can survive a soggy PNW February.

Know Your Microclimates and Soils

In the Pacific Northwest, it’s not enough to say “this plant grows in Seattle.” The site conditions on a client's property—sun exposure, drainage, and soil type—can vary dramatically from one corner to another.

Start by asking:

Where does water pool in winter?
Where does the soil dry out first in summer?
Is the soil clay, loam, or glacial till?
Is there a perched water table or a hardpan layer?

Plants with taproots and fine-textured leaves may survive in sunny berms with lean soil, but rot in shaded clay swales. Use mounding and swales to shape water flow, and be honest about what can grow where. If you want to use winter-sensitive plants like Grevillea or Arctostaphylos, plant them high and dry, with excellent drainage and mineral mulch—not tucked into a bed of compost and bark. Fortunately, HPSO speaker Michael McCoy noted that “Balance is best achieved with a moderate amount of stress.”

*A combination of color and texture from foliage and stalwart summer bloomers at the Albers Vista Garden.*

Timing Is Everything: Why Fall Planting Matters

Most plants adapted to summer-dry climates send out roots in the fall and winter when moisture is available. That makes autumn the best time to plant, giving roots time to establish before the dry season arrives.

Unfortunately, this is when clients are least likely to think about landscaping. Preston Pew of Cistus Nursery, notes that the bulk of nursery sales tend to be in spring and summer; growing quantities for fall leaves the risk of caring for unsold stock all winter. Besides, plants in bloom are putting all their energy into seed production, not root growth when you need it.

Designers working at scale need to plan ahead:

Reserve plants in early summer for fall installation.
Work with nurseries like Cistus Nursery or Xera Plants, who specialize in climate-appropriate selections and understand the timing needed for success.
Explain to clients that smaller, fall-planted starts outperform larger, summer-planted ones in the long run.

Overwatering spring-planted Mediterranean species during hot weather often leads to fast top growth and underdeveloped root systems. Let fall rains do the work to build a more robust plant.

What Plants Work for Tomorrow’s Seattle?

To build a resilient, low-water garden in the Seattle area, look south—not just to Provence, but to California’s coastal hills, Oregon’s Rogue Valley or the Siskiyous, and Chile’s matorral viewable in the developing Traveler’s garden at Heronswood. Look to online resources such as Nora Harlow and Saxon Holt’s Summer Dry project. Visit local botanic gardens to see how established borders continue to shine.

*Sweeps of Stipa, Salvias and Nepetas with Phlomis punctuation makes this border at the Bellevue Botanic Garden Dynamic in Summer without needing a lot of supplemental water.*

Some reliable performers can be found on the Calscape website, such as:

Arctostaphylos spp. (Manzanitas)
Achillea 'Moonshine'
Artemisia ‘Silver Mound’
Ceanothus thyrsiflorus (Blueblossom)
Eriogonum giganteum (St. Catherine’s lace buckwheat)
Eryngium (Sea Holly)
Festuca idahoensis (Idaho fescue)
Penstemon pinifolius (pineleaf beardtongue)
Phlomis russeliana (Turkish sage)
Salvia clevelandii (California blue sage)
Santolina ‘Lemon Fizz’
Stachys ‘Helen Von Stein’
Stipa gigantea ‘Little Giant’

These plants tolerate lean soils, limited summer water, and occasional deep irrigation. Head Gardener at Beth Chatto’s Essex Garden, Åsa Gregers-Warg, now knocks off most of the rich soil that plants are grown in so they don’t take off too early and struggle in the summer heat. Careful management of this garden requires vigilant weeding-out of the prolific Verbascum and other self-seeders. Maintaining a drought-tolerant garden also requires thoughtful plant spacing as most of these plants resent crowding. Many also provide ecological benefits, supporting native bees, moths, and birds.

*The Gravel Garden at Beth Chatto’s containing Alstromeria hybrids, common chive, Salvia sclarea var turkestanica,* *Verbascum bombyciferum, Verbena bonariensis and other plants listed in* *https://www.bethchatto.co.uk/conditions/ plants-for-dry-conditions*

A New Aesthetic for a New Climate

Designing for drought doesn’t mean sacrificing beauty. It means creating gardens that respond to our region’s true conditions—not imported ideals or outdated planting schemes.

We need gardens that:

Look good even when stressed
Require fewer inputs
Support wildlife
Teach clients what resilience looks like

Climate adaptation isn’t just about plant lists. It’s about a whole-systems approach to landscape design—water, soil, microclimate, and maintenance—all working together. With thoughtful planning, the Pacific Northwest can be a model for beautiful, functional, climate-smart gardens.

Designing Resilient Gardens for a Hotter, Drier Pacific Northwest