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Dryland Plants for the Northwest

Making these beautiful, easy-care and eco-friendly plants thrive

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Sedum aizoon 'Euphorboides'

By Emma Elliott

There are good reasons to grow dryland plants in your Northwest garden. Today’s headlines tell us that our climate is likely to become hotter and drier in the coming years with water becoming an increasingly scarce resource. We all lead busy lives and who among us wouldn’t mind spending less time weeding and watering? By keeping a few key concepts in mind, Northwest gardeners can grow beautiful, easy-care and eco-friendly dryland plants in their gardens.

Dryland plants originate in regions with hot, dry summers and survive in these habitats through adaptations such as succulent leaves that retain water, strong root systems that penetrate deeply into the ground and fuzzy, leathery or silvery foliage that protect the plant from excessive heat. They are found in low fertility, very well-drained, sandy and rocky soils. When grown in fertile, clay soils such as those in areas of Western Oregon and Washington, their lifespan may be shortened by rampant growth in summer and lack of oxygen to the roots and rot in winter. Some plants survive but fail to thrive, making them a disappointment to grow.

The good news is that it is relatively easy to create the lean, well-drained soil that dryland plants need. The first step is to assess your soil. If your soil forms a dense clump when squeezed in your fist, you will need to improve drainage before you plant. Soil drainage is greatly improved by adding inorganic soil amendments such as pumice, river sand or quarter-ten size crushed rock.  The crushed rock has been screened to remove the “fines,” or smallest particles, that cause soil compaction. The idea is to create six to twelve inches of light soil made up of variable particle sizes that drain rapidly and allow deep root penetration.

An added benefit of adding inorganic material to your soil is that it decreases the fertility of rich soils. This is the opposite of what we try to achieve by adding compost to a vegetable garden. We want maximum fertility in the vegetable garden because those plants grow, flower, fruit and die in a few short months. In contrast, dryland plants remain healthier and live longer when grown in less-fertile soil.

Most dryland gardens are created in areas that receive at least six hours of sun each day and can be situated on a level or sloped site. Sloped sites naturally make use of gravity to help with drainage while gardens on level sites often use bermed soil or raised beds for best drainage. Mulch is important in the dryland garden. The use of crushed rock as an inorganic mulch to a depth of one to three inches inhibits weeds and retains moisture without increasing fertility. Some gardeners prefer the softer look of organic mulches such as bark. If organic mulch is used, it should be kept it away from the base of plants where it can cause decay.

There is a wide range of plant choices for the dryland garden. The mint family offers a number of colorful, wonderfully scented and familiar plants including rosemary ‘Tuscan Blue’ (Rosmarinus officinalis), lavender ‘Lady Lavender’ (Lavandula angustifolia), hummingbird mint (Agastache aurantiaca) and tiny-leaved ‘Elfin’ creeping thyme. Drought tolerant succulents such as Northwest native broadleaf sedum (Sedum spathulifolium), mounding Russian stonecrop (Sedum kamschaticum) and upright Sedum aizoon are also natural choices. Growing these plants is also good for the environment because they attract pollinators and other beneficial insects to the garden.

Plants with tubular flowers that attract hummingbirds include pine needle penstemon (Penstemon pinifolius), Northwest native shrubby penstemon (Penstemon fruticosus) and California fuchsia (Zauschneria californica). Create splashes of color with members of the shrubby rockrose family Cistus incanus and Helianthemum mummularium mutabile. Dryland grasses include Mexican feather grass (Nassella tenuissima), tufted fescue ‘Superba’ (Festuca amethystina) and blue wheatgrass (Elymus magellicanus).

For best results, provide occasional supplemental water to your garden during the driest part of the year. This is particularly important during the first season after planting while plants are becoming established. Drip irrigation is ideal because water is delivered directly to the base of the plants, watering deeply while conserving water and inhibiting the growth of weeds. Other eco-friendly features of the dryland garden are that it does not need to be fertilized and rarely has pests.  NWGN

Emma Elliott is with Wild Ginger Farm, 24000 S Schuebel School Rd Beavercreek, OR 97004, 503-632-2338, e-mail info@wildgingerfarm.com

 






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