Yards and gardens can really suffer in times of drought and heat. Washington State University Extension delivers a lot of advice to grow a beautiful and drought-tolerant landscape, including lists of plants, tips for reducing water usage, and more.
You can learn more from the free “Drought Tolerant Landscaping for Washington State (Home Garden Series)” from WSU Extension. Here are a few ideas to start you out from the Extension guide:
Pick the right plants
Drought-tolerant plants can withstand some time with limited moisture, even if they do not prefer periods of hot, dry weather.
Woody plants can store water in both their roots and their trunks, thus surviving dry periods. Drought-tolerant species have thick, waxy, or hairy leaves that minimize water loss (Fair 2009). Examples of these species would include Gilt Edge Serviceberry, Oregon grape, and Delavay Osmanthus.
Plants with small, fine, or deeply divided foliage are considered drought tolerant (Mickelbart and Jenks 2012). Conifers have both small leaves and waxy cuticles, thus limiting the amount of water loss due to normal leaf transpiration.
Deciduous trees whose leaves have deep sinuses (indentation between the lobes) reduce water loss as they have less surface area (Mickelbart 2012). Red maple, for instance, is a very popular shade tree for Washington state as it very drought tolerant (Tirmenstein 1991).
Turf grass, such as perennial ryegrass (Lolium perenne), is classified as a drought avoider as it will go into summer dormancy where the blades of grass turn brown and dry out when not irrigated. However, the plant will come back almost entirely in the fall when the rains return.
Herbaceous perennials vary tremendously in their ability to withstand drought as they do not have the reserve capacity of woody plants. Once again the perennials that lack thick leaves or lignified (woody) stems are the first to grow, flower, and then go into seasonal dormancy as summer heat progresses.
The guide has lists and photos of drought-tolerant plants.
Conserve water
When you landscape for hot weather, you conserve water.
“Unless landscape plants are fully established, which commonly takes 1 or 2 years, they can suffer from summer drought on hot days. Supplemental irrigation is used to counter the effect of drought. It is not uncommon to find that 80% of all the water used around the home is used outside during the summer months (Fresenburg 2010). Increased irrigation puts pressure on municipalities to expand water supplies and homeowners will also see a significant increase in their water utility bills if they use many gallons of water for their thirsty landscapes.” — Drought Tolerant Landscaping for Washington State
One technique is to use hydrozones, landscape areas with plants that have similar water needs. These can help you determine how much irrigation and water is needed in a given hydrozone.
An efficient irrigation system and using less turfgrass can also help reduce water usage.
Good soil, healthy plants
A drought-tolerant landscape consists of healthy soil, such as native soils, with good soil structure that allows the soil to be infiltrated and to hold water. Native soils absorb high rates of water during the winter, thus minimizing surface-water runoff and erosion. These soils trap sediments and excess nutrients, all the while supporting a host of different fungi, bacteria, and earthworms that fight pests and diseases.
You can also use mulch to prevent soil drying and preserve moisture.
Learn more at WSU Extension’s Drought, Conservation, and Irrigation website. They also offer other useful landscaping guides: