Caleb Melchior has extensive experience with growing perennials after working at a specialty perennial nursery, Sugar Creek Gardens, in Kirkwood, Missouri. He is currently studying for a master’s degree in landscape architecture at Kansas State University.

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The Dog Days Are Over: Summer Blues to Turn Down the Heat
by Caleb Melchior    

My garden always starts to look tired in August. The roses have long since faded and given up. The daylilies are done screaming “orange!” in the corners. Even the annuals, the proud cheerleaders of color, have exhausted themselves in the heat.

But on those first August mornings, when the Caryopteris and Perovskia start to flower, everything changes. The dog days are over, washed away by floods of flowing, flowering blue. 

Caryopteris x clandonensis ‘Heavenly Blue’ offers powder-blue foliage with a wispy appeal in late summer.

Caryopteris x clandonensis ‘Worchester Gold’ looks fantastic throughout the growing season, with its beautiful chartreuse foliage.

Caryopteris spp.

Late summer begins for me when the first pale blue flowers start to trickle out on the caryopteris. The caryopteris, also known as blue mist shrub, is a shrublet, or woody perennial, which — depending on the selection — can grow anywhere from 3 to 6 feet high and wide. As much as I hate to bandy botanical names, the common names for these plants are highly confused and nowhere near standardized.

The most widely grown hybrids are in the group of hybrids under the name Caryopteris x clandonensis, bred from Caryopteris incana, which is native to Eastern Asia, and Caryopteris mongholica, which grows in Western China and parts of Mongolia. While neither of the parent forms are widely grown, the hybrids are beloved of discerning gardeners in the U.S. and Britain.

Among the Caryopteris x clandonensis hybrids, ‘Dark Knight’, ‘Heavenly Blue’ and ‘Longwood Blue’ (hardy from Zones 5 through 9) are three of the most common. ‘Dark Knight’ has strong deep-blue flowers, not quite navy, more a fuzzy cobalt. ‘Heavenly Blue’ and ‘Longwood Blue’ are lighter in hue, with frothy pale blue flowers. One of my garden favorites for several years, ‘Worchester Gold’, glows throughout the growing season with pale chartreuse leaves and powder blue flowers.

Over the past five years, several new forms with more compact habits have been released. ‘Petit Bleu’ is a dwarf variety with extra-large flower clusters in rich blue. ‘Gold Giant, Hint of Gold™ and Lil’ Miss Sunshine™ have gold foliage. Their texture is coarser than that of ‘Worchester Gold’, giving them a chunkier, bolder appearance. ‘Sterling Silver’ has shining silver foliage. There is also a clear white variegated form, ‘White Surprise’.

Given all these varieties, it is surprising that Caryopteris are not more widely used. They look fantastic throughout the growing season, with their colorful foliage, and erupt into masses of blue flowers in late summer. Perhaps their limited use occurs because they’re timid plants, waiting to leaf out until spring has definitely rounded the corner and there’s no risk of frost before leafing out. Anxious gardeners often pull them out, thinking they’re dead, when they’re actually just waiting for warmer weather. Come August, they’ll be glorious.

Caryopteris ‘Snow Fairy’ (middle, foreground) glows with cream-edged foliage within the rough and tumble of a perennial border.

Perovskia spp.

Russian sage (Perovskia atriplicifolia) manages to appear icy cool in the midst of a sweltering Missouri afternoon.

Up close, the flowers of Russian sage (Perovskia atriplicifolia) reveal their fuzzy texture, which helps them reflect heat rather than absorbing it.

When I think of plants to overwhelm the dog days of summer with refreshing blue, my brain turns to the iciest of them all. While we’re sticking with botanical Latin, Perovskia atriplicifolia has a genuinely chilling name that echoes back to its homes on the steppes of Russia and Afghanistan. Under the common name of Russian sage, it was the poster-child plant for late 1990s garden style. Anybody who gardened in those giddy days of early perennial infatuation did not dare to make a garden without it, most often combined with gold yarrow (Achillea x ‘Moonshine’) and huge clumps of maiden grass (Miscanthus sinensis). Past overuse, however, is no reason to ignore a perfectly good plant. Today, we appreciate that Russian sage’s frosted foliage and silvery blue flowers that make a perfect foil for drifts of diffuse perennials — low-flying clouds of ‘Starry Night’ white shrub roses (Rosa x ‘Starry Night’) and huge mauve billows of Joe Pye weed (Eupatorium purpureum).

Forms of Russian sage are confused in the trade, with plants varying in their silveriness of foliage and overall plant and foliage texture. Plants sold as ‘Filigran’ tend to have more dissected leaves, while those sold as ‘Longin’ are supposed to be smaller with less finely cut foliage. ‘Little Spire’ is a compact cultivar, growing to only 2 feet high. ‘Lacy Blue’ is a new compact variety with exceptionally large flowers.

Your history with Russian sage may be limited to grocery store parking lots and seductive magazine dream gardens left over from the 1990s, but don’t hesitate to clear space in your border for a few of these brilliant “cooling” clouds of flower and foliage. All that Russian sage requires is a bit of breathing room. When crowded, it rots, goes leggy, and — eventually — dies.

The steamy nights of late summer still have a few weeks of fight in them before they give up and let the sweater evenings come crashing in. Given that most of the garden is probably looking worn, clear out some of the overgrowth to make way for the icy blues of Caryopteris and Perovskia. With their clouds of blue flowers and pale foliage, they’ll bring the temperature of the garden down to something bearable.

Photos courtesy of Caleb Melchior


Posted: 08/02/13   RSS | Print


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