What’s Blooming Now: Early Autumn in the Pacific Northwest
October 9, 2018
Striking autumn colors!
As the days become shorter and cooler in Seattle, we say goodbye to the diversity of spring and summer blossoms and shift toward the luscious colors of autumn. This month, we want to celebrate the arrival of autumn by featuring a few plants that we love to use in projects of all styles and sizes that are especially lovely early in the season. The unique seasonal colors and sculptural structures of these plants provide interest and versatility in a range of landscapes from gardens to commercial landscapes and streetscapes.
The Katsura tree (Cercidiphyllum japonicum) is a staple of Seattle neighborhoods. One of the first deciduous trees to change color and drop its leaves in autumn, Katsuras put on a brilliant display in mid-September to early October. With a finely branching habit and delicate heart-shaped leaves, these trees are lovely year-round, providing dappled shade on local streets throughout Seattle.
Shown Above: Katsura Tree – Cercidiphyllum japonicum
In autumn, the trees flush from top to bottom with foliage colors ranging from pale buttery yellow to deep rust red, depending on sun exposure and water availability. Especially noticeable on cooler days, some Katsuras also exude a sugary, vanilla-like smell as their leaves change color, making these trees one of our all-around favorite sensory experiences of fall.
Due to their shallow root systems, Katsuras make excellent street trees (where there are no overhead powerlines). They stay fairly small with open, loosely pyramidal canopies reaching up to 30 feet tall and 20-25 feet wide. Although their shallow roots make them great for urban sites, they may struggle if planted in areas with high traffic paths where their roots are not protected by sturdy hardscape. Native to Japan, Katsuras are well-adapted to our temperate climate and do well as shade garden accents or elegant, dappled screens if planted in a row. A favorite of the late landscape architect, Richard Haag, who is renowned locally and internationally for projects like Gas Works Park, Seattleites have Richard to thank for many of the luminous Katsura canopies we see in Seattle today.
A treasured native species, Vine Maple (Acer circinatum), has some of the most brilliant and diverse fall color in our region. Adapted to grow as a shrub or small tree in the shade of tall conifer forests, Vine Maples tend to have a graceful upright branching habit that can be grown as multi-stem shrubs or single stem trees.
Shown Above: Vine Maple – Acer circinatum
Depending on growing conditions and sun exposure, Vine Maples may begin changing color as early as July and slowly continue to shift in color throughout September and into October. The color range of Vine Maples is immense, a single leaf may be bright yellow, burnt orange and deep purple all at once! If grown with partial to full sun exposure, leaves will turn rich fiery colors and begin shedding in September often continuing to change colors through October.
Vine Maples grown in deep to dappled shade will hold their leaves, remaining green longer than trees with direct sun exposure, eventually turning pale, ghostly yellow before shedding leaves in October. Vine Maples are one of our all-time favorites for a variety of uses from screening hedges to sculptural accent planting, native woodlands, and restoration.
We also love some of its more colorful cultivars like ‘Pacific Fire’ that has bright red stems and branches for added winter interest. These trees thrive best in partial sun to full shade with consistent water. They can be trained or shaped as desired but will usually form a beautiful small tree if left to grow naturally.
Stonecrops (Sedum ssp.) are an extremely diverse genus of succulents that usually thrive in poor, rocky soils and dry, hot conditions. We love this whole genus for its tough, drought tolerant groundcovers that provide a range of textures and colors, like Broadleaf Stonecrop (Sedum spathulifolium), Angelina Stonecrop (Sedum rupestre ‘Angelina’) and White Diamond Stonecrop (Sedum pachyclados ‘White Diamond’).
But our favorite, and most often used of this genus is the Autumn Joy Stonecrop (Sedum ‘Autumn Joy’). The icon of sedums, Autumn Joy is taller than its creeping relatives and grows up to 24” tall, with flat umbels of flowers that often reach 2-3 inches across at maturity. The fleshy, bright green stems and leaves begin to emerge from winter-dormant crowns in late spring, growing taller throughout the summer and eventually blooming in September. The bright, coral pink blossoms are a highlight of the September garden, providing late forage for bees and a stunning color display that usually lasts into October.
Shown Above: Autumn Joy Stonecrop – Sedum ssp. ‘Autumn Joy’
We recommend planting Autumn Joy in clumps or rows in bright, sunny locations with grasses, evergreen shrubs or other perennials for a stunning seasonal accent. If left throughout winter, the stems and spent flower heads provide striking structural interest and shelter and forage for beneficial insects.