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Green Gardening: Dry plants need sun and drainage
By ANN LOVEJOY
SPECIAL TO THE P-I
LAST WEEK I offered ideas about smaller shrubs and grasses that grow well in dry gardens. Some of you want to know if you can simply grow drought-tolerant plants in an ordinary garden bed and not water them. Well, yes and no. The dry-garden style involves mounded beds and gravel mulches that promote winter drainage and good air exchange. This helps reduce winter root rots that can plague ordinary garden beds when their base is heavy clay soil. Dry gardens support a wide variety of plants that love to be dry and hate to be soggy. Some of these simply won’t accept a spot in an “ordinary” bed.
That said, many dry-land plants will grow happily in a typical garden bed as long as the drainage is adequate and the site is sunny and open. Certain shrubs are very tolerant of average garden conditions and can be weaned off the water in a season or two. Among these, the rockrose (Cistus) family offers a limited but pleasing array of shrubs in the 3- to 6-foot range.
Short-lived but showy, rockroses provide a terrific display in exchange for very little attention. They do best in open, sunny, windswept sites with excellent air exchange. Sunny slopes are particularly good spots for cistus, which bloom in white, lavender or shades of pink from baby ribbon to deep rose and magenta.
Somewhat similar looking at first glance (roundy-moundy in shape, with single-rose type flowers), the Potentilla clan also ranges from 3 to 6 feet and thrives in dry, sunny places. Reliable, pest-resistant, drought-tolerant, naturally shapely and disease-free, these tough plants reward garden space with effortless bloom.
Besides our soft yellow native species, the garden hybrids range from clean white through apricot, lemon, primrose and tangerine to coral, pink and rose. The so-called “red” potentillas, such as ‘Red Ace’ and ‘Sunset,’ look washed out in hotter climates but are at their best in the cool Northwest.
Beach rose (Rosa rugosa) is another strong performer, flowering off and on through the summer without supplemental water. These sturdy shrubs combine dense, healthy foliage with large and highly fragrant flowers in white, pink, rose, red or amber. Many have lovely fall colors and plump, pretty hips in winter as well. A few have wandering ways (such as the notorious drifter ‘Blanc Double de Couvert’) but given adequate room, today’s hybrids are mannerly and pretty much maintenance free.
California lilac (Ceanothus) loves a hot, dry, unwatered slope, yet many forms do just fine in ordinary garden beds. This evergreen shrub comes in a full range of sizes, from ground covering ‘Point Reyes’ to the lush abundance of ‘Victoria,’ a large and graceful shrub that may exceed 8 feet when happy.
Many of the barberries (Berberis) thrive in dry gardens. These small-leaved shrubs offer lovely foliage in green, bronze, rose, purple, gold or chartreuse, with small orange or golden flowers and bright berries in yellow, orange or red. Some are evergreen, others deciduous, but all are drought tolerant and very easy to please (though prickly).
Plenty of perennials do just fine in dry gardens, but a few stand out for strong growth and good manners. Of the flat-flowered yarrows (Achillea), modern hybrids such as ‘Terra Cotta,’ ‘Paprika’ and ‘Summer Wine’ are far less thuggish than old-fashioned runners like ‘Coronation Gold.’ Yarrows are classically partnered with grasses and rocks, as are black-eyed Susans (Rudbeckia).
Structural and handsome even in winter, the rudbeckias grow happily without water once established. ‘Goldsturm,’ a tall plant with golden flowers, is highly popular with grasses, as is ‘Black Beauty’ (yellow with big black eyes). Helianthus or prairie sunflowers are also great dry-garden plants. A few are rather aggressive (Helianthus ‘Lemon Queen’ being one to plant warily) but ‘Golden Pyramid’ and ‘Autumn Glory’ are choice.