GARDENER'S READING ROOM
The Art of Gardening
Trees & Shrubs

Fall Color for Northwest Gardens

For those of us who love to garden, watching our plants develop deepens our connection to them and our understanding of their individual attributes and requirements. Observing them gives us a chance to imagine combinations for appealing texture and color. In autumn, as our gardens prepare for winter, new possibilities emerge, drawing our attention to foliage color and bark texture.

Although some evergreens take on rusty winter hues, it is deciduous shrubs and trees that glow in the soft light of fall. This transformation is due to changes within their leaves. Shortening days cause plants to stop supplying nutrients to their leaves. As a result, they cease production of chlorophyll, the unstable, energy-gathering pigment that makes leaves appear green. Without chlorophyll, other leaf pigments are unmasked and have a chance to "show off."

As you've undoubtedly noticed in fall, the main colors are yellows (caused by carotene, as found in carrots) and reds (caused by anthocyanins, as found in red apples). The combination of these pigments, revealed, gives a plant its fall pigment. Anthocyanins respond to concentrated leaf sugars by becoming darker in color – hence the great fall color in regions with cool nights and dry days, which concentrate sugars. If we have a rainy fall, colors are not as intense as they would be during a chilly, sunny fall.

Although we can't boast the spectacular fall colors seen to the east, our adaptable little native vine maple (Acer circinatum) puts on a good show. First to turn red, its flames intensify after a dry summer. A multi-stemmed shrub/tree, vine maple is well adapted to our west-coast dry spells. Its closest relative is Japanese maple (Acer palmatum), also noted for handsome fall color, which varies by cultivar. 'Sangu kaku' turns butterscotch, while 'Bloodgood' turns scarlet.

Last fall, the nursery staff here at Sky Nursery oohed and aahed over the yellow and red fall colors of Nyssa sylvatica 'Autumn Cascade'. It thrives in moist soil and can be staked to whatever height is desired as it produces its gently weeping side branches.

Stewartia bark

Japanese stewartia (Stewartia pseudocamellia) is an outstanding small tree, reaching 12 feet in ten years. Midsummer brings white, camellia-like blossoms that float among its branches; in fall it blazes deep orange. As it matures, Japanese stewartia develops a patchwork bark of pink-grey and red-brown, making it truly a four-season tree.

Also noted for year-round good looks are witch hazels (Hamamelis). These wide-spreading shrubs get to 8 feet high and wide in ten years. Splendid set against a backdrop of dark conifers, witch hazels bloom in late winter, producing yellow, orange or dark red flowers along bare branches. Their attractive leaves turn equally vivid shades in autumn.

	Ginkgo biloba

Perhaps the brightest autumn hues come from ginkgos (Ginkgo biloba), whose distinctive leaves turn into little golden fans with the onset of cool night temperatures. 'Tubiformis' has unusual rolled leaves, while Golden Colonnade is noted for an oval-shaped crown, much narrower than many other cultivars. Ginkgos are entirely pest- and disease-free, hardly surprising for a species that has been on earth - little changed - since the Jurassic period!

Disanthus cercidifolius Photo by Carolyn Jones

While most plants need sun for good fall color, two shrubs "color up" reliably even in some shade. During summer, the leaves of smoke tree (Cotinus) 'Grace'are burgundy, but in autumn they turn deep orange. Redbud hazel (Disanthus cercidifolius) is an uncommon shrub related to witch hazels. Even in shade, it takes on brilliant fall hues. At first, its grey-green heart-shaped leaves take on bronze tones. As temperatures drop, they turn orange and gold and finish bright red. Strung along its horizontal branches, these look like cut-paper valentines, especially when caught in shafts of autumn light.

While you're checking out Sky Nursery's supply of fall color plants, be sure not to miss the perennials and seasonal plants in our beautiful new greenhouse. Heathers, asters, mums, grasses, pansies and winter cabbages top off the display in any fall garden or container.

By Carolyn Jones
Skylights Autumn 2009, Vol 24, No. 3

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