October may be unlike any other month in the garden, defined as it is by one plant, the chrysanthemum.
Floral nitpickers will say the mum is not one plant, but a smorgasbord of hybrids developed over centuries. So-called Korean mums are lovely, daisylike blooms to brighten the late-season garden. A variety named Sheffield Pink is particularly handsome. But Korean mums are lovely because they maintain a sense of nature, with open, flat blooms and a relaxed habit.
The predominant cushion mum now adorning commercial landscapes and garden beds is much harder to love, not because the colors are so grabby but because the shape is so perfectly dull. Uniform mounds, in turn, encourage landscapers to plant them in ribbons, or alternating stripes or such. Passing a downtown hotel these days is like watching those opening routines in the Beijing Olympics, eye-popping and artfully choreographed but all a bit make-believe.
The best October gardens are those that have loosened their grip on the chrysanthemum, and if you were to rely more on other plants -- asters, salvias and hyssops, to name a few contenders -- your garden would be eye-catching in an entirely different way.
Asters are hardworking native perennials, long-flowering and joyously blue (and other hues), though it pays to pick selected varieties that don't flop so much or become chalked by powdery mildew. One trick is to prune back asters by about half in late May, so that they grow bushier. Two of my favorites are Raydon's Favorite and October Skies, both compact forms that don't need spring trimming, and with masses of lavender-blue blossoms in early fall.
Snow Flurry, a heath aster whose leaves resemble the needlelike leaves of heaths, grows to just eight or nine inches. The perennial is smothered in white blooms with yellow centers and is useful for filling late-season gaps, perhaps where bulbs grew in the spring.
The tartarian daisy or aster is known for growing tall while being self-supporting and is worth a go, but a variety named Jindai is about three feet tall, half the usual size, and with distinctive and large aster flowers with pronounced yellow centers.
The hyssops, or agastaches, are spiky perennials from the Southwest and Mexico that have become really popular in recent years for their tubular flowers, loved by hummingbirds, licorice scent and insistence on blooming continuously from late summer on. In return for all this, they ask two things of the gardener: a sunny site and free-draining soil. Some are purple, some salmon and orange, and others violet-rose. As with salvias, agastache flowers emerge from a base called a calyx, which can be as colorful as the petals themselves, and prolong the ornament after the flowers fall. Both Agastache rupestris and Agastache cana have been great performers in my garden, and return reliably.
No fall garden is complete without a sage (salvia) or two. Some of the autumn sages are not winter-hardy but are still worth growing as annuals. But many of them are hardy, far more so than we ever thought. Again, the key is exceedingly good draining to avoid wet soil in winter dormancy that will rot the crowns. Also, avoid heavy organic mulches.
At Green Spring Gardens west of Alexandria, horticulturist and salvia fancier Nancy Olney has had stunning success with various types. In the garden center's long border, a mixed planting bed next to the parking lot, she has clumped three Mexican bush sages, variety Midnight, and together they have all the presence of a large and floriferous shrub. The blossoms are as long as 12 inches and covered in individual flowers of mauve-purple tubes resting in deep-purple calyxes. They appear to have been fashioned from velvet.
"It's been coming back now for eight years," said Olney. Next to it, she has planted another tall sage called Salvia guaranitica Black and Blue, named for its azure-blue flowers in near-black calyxes. The leaves are a soft yellow-green.
One of most beautiful sages is the Salvia splendens Van Houttii . The flowers are large and a deep wine color and can look stunning in chance pairings with changing leaf colors of nearby shrubs. However, it is one of the most tender sages, and even ideal site conditions will not save it from the frost, says Olney. Hot Lips is a dainty red and white form of the little-leafed autumn sage and blooms effectively from late summer until frost. It will get through a mild winter, but be prepared to replace it in the spring.