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.
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.
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.
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
lavender ‘Lady Lavender’ (Lavandula angustifolia), hummingbird
tiny-leaved ‘Elfin’ creeping thyme. Drought tolerant succulents such as
Northwest native broadleaf sedum (Sedum spathulifolium),
mounding Russian stonecrop (Sedum
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
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
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