Typically, June is still a misty month in Seattle, which helps plants survive the region’s typical dry season from July through September. But those Junes haven’t been happening for the past several years, and this year has shown that our dry season can get very dry.
And the trend is expected to continue.
“We’re expecting hotter weather and more drought” in the Pacific Northwest, says Kate Kurtz, Seattle Public Utility’s organics and landscape resource conservation planner. To combat future climate change, she recommends modifying your approach to your home’s landscape
“Look at your plants now,” Kurtz says. “This is the most stressed they’re going to be, in late summer.”
If your yard is currently a crime scene of dead and dying plants, investigate the causes and prepare to pivot to a more drought-tolerant approach.
The root of the problem
To make a change, start with the soil. Healthy soil will retain more water, whether it comes via fleeting rain or your garden hose. A healthy base will act like a sponge, Kurtz says, which prevents plants from drying out.
She says future rainfall may come in the form of hard-hitting flash storms rather than Seattle’s typical fine mist. Poor soil sends pollutant-carrying water to drains, streams and the Puget Sound, sullying regional water quality. But because most Seattle property is privately owned, homeowners who create water-wise and climate-friendly landscapes can lessen the effects of this runoff.
To boost your soil’s health, Kurtz suggests adding nutrients by mixing 2-3 inches of compost into existing dirt. For lawns, rake a quarter-inch or so of compost into the grass annually. Every few years, add a couple of inches of compost around the base of perennials, shrubs and other established landscaping.
Soil amended with compost will also teem with healthy microorganisms, which help defend against plant pathogens, viruses and fungi. Plants with a depleted soil system can more easily fall prey to such threats.
Maintaining healthy soil and plants can also reduce the need to use pesticides and herbicides — even “natural” or “organic” formulations, which can still kill off beneficial insects, Kurtz says.
Attracting and keeping beneficial insects in your yard can be one of the best defenses against bugs you don’t want. For example, ladybugs and lacewings feed on aphids, scale insects and mites. Yellow jackets try to chow down on your barbecued meat because they’re carnivores — and, therefore, they also devour many garden pests.
Climate change will impact our approach to watering, as well. Maintaining a strong, well-hydrated root systems will heighten your plants’ resiliency during droughts, Kurtz says.
Established plants, trees and shrubs only need occasional water, even in very dry, hot summers like this one. Run a soaker hose about 30 to 40 minutes a week to water a plant’s root system deeply; this can vary depending on the plant and soil type.
Then check your work. An hour after watering, use a trowel to dig 6-12 inches and see if the soil is damp throughout a plant’s entire root zone.
Laura Matter, program director of sustainable yard and home education at Tilth Alliance, says many homeowners who are struggling with dry, dying gardens this summer have been reaching out to the Seattle nonprofit’s Garden Hotline at 206-633-0224 or gardenhotline.org for help.
She says the staff of professional horticulturists and educators are telling callers that preparation and prevention are key to getting your garden through this year and thriving in the future.
If a heat wave is in the forecast, for instance, Matter suggests watering the day before temperatures are expected to spike. If certain plants have sunburned in the past (evidenced by turning white), cover them with shade cloth or move them to covered areas prior to the hottest days.
Adding mulch around trees and shrubs helps them retain water by reducing evaporation. Mulch also acts as insulation so the soil doesn’t get as hot, Matter says.
As for lawns, even if your grass hasn’t been green in months, don’t give up on it just yet.
“Lawns get a bad rap,” Kurtz says. Often viewed as water-hogs requiring high levels of maintenance, lawns can be made more ecologically friendly by mixing in drought-tolerant species such as clover and blue star creeper.
It’s fine to let your lawn “go golden” in the summer, Kurtz says. Water it once a month, and try to avoid using the area heavily, or you may find it doesn’t turn green again when the rains return.
Plants for a new climate
If a plant didn’t make it this year, don’t replace it with the same species, Kurtz says. Now is the time to search for more heat- and drought-resistant options. Matter suggests drought-tolerant plants such as California lilac (ceanothus), shrubby cinquefoil (potentilla), rock rose (cistus), hebe, and shrubby lavender and rosemary.
Seattleites can look to dryer regions in Oregon and Northern California for species that could thrive here. For example, Kurtz says that an incense cedar (Calocedrus decurrens), more common at higher elevations, might be better able to adapt to a drier climate than a water-craving Western red cedar.
Near Carnation, a pilot project is experimenting with reforestation using native trees — such as Douglas firs and other conifers — that have adapted to drier conditions in southern Oregon. If they do well, expect these trees and plants to start showing up in local nurseries, Matter says.
“Native plants are more adapted to this region, which gives them a good chance of success,” Kurtz says.
Matter’s native recommendations include ocean spray, red flowering currant and dogwoods. Native-grass lawn seed won’t be quite as water-needy and can grow a little taller; mix wildflowers in for beauty.
But even drought-tolerant greenery needs extra care while getting established. For trees, use a donut-shaped watering bag and fill it twice a week from May through September. Or water for 20 minutes with a small trickle from a garden hose at the tree base.
Most garden centers have knowledgeable buyers and salespeople who can help you find the right plant for the right location in your garden, depending on slope, shade, sun and other variables. Some Seattle-area homes have boggy backyards, while others may run hot and dry.
This year has been a great learning opportunity for gardeners, Kurtz says, because we can expect more dry summers, more heat domes and more dry soil in the future.
“Look at what failed [to grow], and ask what you can do differently, but don’t give up,” she says. “Our trees, soils and landscapes are a shared natural resource that have the potential to impact our entire community, just like air and water quality.”
Resources for gardeners
City and regional programs can help you prepare for climate change’s impacts on our yards and gardens — and mitigate those impacts overall. For example, Seattle’s Trees for Neighborhoods program’s free trees provide shade to you while pulling additional carbon out of the atmosphere and decreasing the intensity of urban “heat islands.”
Here are several other resources with information about native plant choices, soil amendment, efficient watering and more.
NATIVE PLAN RECOMMENDATIONS
• King County: kingcounty.gov/gonative
• City of Seattle: seattle.gov/documents/departments/SPU/environmentconservation/ThePlantList.pdf
• Washington Native Plant Society: wnps.org/native-gardening/resources#habitat
SPECIAL EVENTS AND OFFERS
• Free compost giveaway: seattle.gov/utilities/your-services/collection-and-disposal/recycling/beyond-the-cart
• Sprinkler timer rebates: seattle.gov/utilities/protecting-our-environment/sustainability-tips/conserve-water/for-residents
• Calculate how much compost your soil needs: savingwater.org/lawn-garden/soil-mulch-compost-fertilizers/compost-mulch-calculator
• Smart watering tips: seattle.gov/utilities/protecting-our-environment/sustainability-tips/landscaping/for-residents/smart-watering
• Adding rain gardens and cisterns: 700milliongallons.org/rainwise