No, Dusty Miller wasn’t a prospector or cowboy with a fine garden. Rather, dusty millers are so-called because their leaves have the appearance of a dusty miller – someone who spends his time in a mill grinding wheat into flour, and subsequently is covered with powdery white dust. This, at least, is the etymology given in the Oxford English Dictionary.
Practically all dusty millers are in the daisy family (Compositae). Their flowers are yellow, white or violet buttons that, in the opinion of some, detract from the plants’ ethereal effect. Dusty millers are grown mostly for their foliage. In fact, it is common practice to remove flower buds before they open; energy that would be used for producing ordinary flowers instead will go to production of ever more snowflake leaves.
The first dusty millers you probably will encounter are Senecio cineraria (grows to 3 feet) and Centaurea cineraria (only a foot and a half tall at maturity). The species name ‘cineraria’ derives from the Latin word for ashes, whose color is found in dusty miller leaves.
Although perennials, they usually are grouped with sun-loving annuals in the nursery. In a flower bed, they present a stunning contrast to the red of scarlet sage (Salvia splendens), the blue of “Crystal Palace” lobelia, or the yellow of African marigolds.
The problem here is that dusty millers, even in the hottest weather, will require, at most, a single weekly soaking, whereas annual flowers benefit from being watered twice a week. When dusty millers are over watered they develop rank growth and spindly shoots, and they lose their compactness.
If your experience with dusty millers was confined to the above species, your fascination with them might be short-lived. They end up outgrowing the annuals they were meant to complement, but are not of sufficient stature to stand on their own. Make sure you experience Senecio vira-vira and Centaurea gynocarpa, both of which grow to more than 4 feet and have foliage that is nearly white.
In terms of water economy, they should be combined with lantana, lavender or old-fashioned zonal geraniums.
Dusty millers are among the easiest plants to propagate. Four and a half years ago, I stuck unrooted 6-inch cuttings of Centaurea gymnocarpa in a 100- foot long planter. Today, a 5-foot tall hedge fills the area; it is pruned twice a year and never watered.
The leaves of dusty millers have three characteristics that impart drought tolerance: silver-gray color, pubescence and deeply cut lobes. Their color is an efficient light reflector, their pubescence is an insulating coat, and their many lobes reduce surface area for water loss from transpiration.
Perhaps the most interesting group of dusty miller-type plants are the wormwoods (Artemisia species). They are medicinal, alcoholic, ornamental and native to this area.
The common wormwood (Artemisia absinthium) has a legendary reputation for curing stomach ills. At one time, people with stomach problems were said to have “worms.” Juice extracted from Artemisia leaves and powders made from its dried blooms were supposed to alleviate indigestion, stop flatulence and promote appetite. Absinthe, also derived from this plant, was a green liqueur imbibed by the impressionist artists who frequented the Moulin Rouge in Paris 100 years ago. Vermouth – the German word for wormwood – is another alcoholic beverage.
Tip of the week
Dusty millers, like most other perennials, look their best when planted in clumps of five or seven or 15. The downfall of the ornamental garden is timidity or indecisiveness, expressed in planting solitary specimens of many different and unrelated species. Now if you were to plant many kinds of dusty millers together – that also would be something to see.