594 Senecio cinerariaCommon Names: dusty miller Family: Asteraceae (aster/daisy Family)
There are at least eight different garden plants commonly called "dusty miller". All are characterized by woolly, silvery-gray foliage; a low, moundlike habit; drought tolerance; and an appreciation of full sun. This one is perhaps the most well known to American gardeners.
Senecio cineraria is a mound forming subshrub that is grown as an annual in cool areas and in areas that experience wet summers. The leaves are silver-gray and woolly, like felt. They are shallowly to deeply incised. In the latter case there can be many blunt tipped, sometimes almost fernlike, lobes. It can get up to 2 ft (0.6 m) tall with a slightly greater spread, but usually only gets half that size in a single season. If it does survive into its second summer, Senecio cineraria produces mustard yellow flower heads about 1 in (2.5 cm) across in loose, terminal, flat topped clusters (corymbs, actually), about 4 in (10.2 cm) across. The flowers are the best way to distinguish Senecio cineraria from all the other dusty millers, but unfortunately, most gardeners never see the flowers.
There are many named cultivars, including several that are dwarfed, getting no more than a foot across, and some with leaves that are so deeply incised as to be lacy.
Senecio cineraria is native to the western and central Mediterranean region where it grows in arid, scrublike habitats. It prefers summers that are warm and dry and winters that are cool (not cold) and wet.
CultureLight: Full sun. Moisture: This dusty miller does best in well drained, even sandy soils with regular watering. It is fairly drought tolerant once established, but should be watered during prolonged dry periods. New plantings may require daily watering, especially in sandy soils, until the roots (which can cover a lot of area) are well developed. Senecio cineraria gets a rust disease and dies during prolonged hot, wet periods. Hardiness: USDA Zones 8 - 10. Senecio cineraria is usually grown as a winter annual in subtropical climates like Florida and the Gulf Coast. It can take the heat, but not the frequent summer rain. In Mediterranean climates that don't get so much summertime rain, like California, it is grown as a perennial shrub. In colder climates, Senecio cineraria is grown as a summer annual, usually started indoors from seed prior to setting out after the last frost. Propagation: By cuttings from semi-hard stem tips in summer, and by seed. Do not cover the seed.
Senecio cineraria is excellent for edging borders and beds. Its silvery-gray foliage provides a perfect contrast for brightly colored annuals. It is often used in containers and window boxes. Gardeners everywhere have created their own original designs with Dusty Miller and their favorite annual flowers. The fuzzy, gray leaves practically glow in a moonlit garden. Some gardeners cut off the flowers as soon as they appear, so as to encourage more foliage. The foliage makes an excellent backdrop to cut flowers in floral arrangements. It is spectacular with red roses!
Hortus Third lists seven other plants with the same "Dusty Miller" common name. These are: Lychnis coronaria, a campion in the family Caryophyllaceae; and six other species in the Asteraceae: Chrysanthemum ptarmiciflorum; three knapweeds: Centaurea cineraria, C. gymnocarpa, and C. ragusiana; Senecio viravira; and the wormwood, Artemisia stelleriana. We could say, "This is why botanists and serious horticulturists use botanical names." But then you might remind us that Senecio cineraria has had six different botanical names! These are: Senecio bicolor, S. candicans, S. maritimus, Cineraria maritima, and Centaurea maritima cv. 'Diamond'. Of course, it has only one ACCEPTED botanical name now, while it still must share its common name with seven other species!
As for all those botanical synonyms: When an expert thinks he or she has discovered an undescribed species that doesn't yet have a botanical name, he or she may name it. Later, another expert (maybe the same expert, now older and wiser) might realize that the plant already had a name, and since the original name must prevail, the newer one becomes a synonym. That's how the three Senecio synonyms came about. Another way a plant can get a synonym is if some expert decides that the species has been placed mistakenly in the wrong genus. He or she might erect a new genus, or move the species into some other genus. When that happens, the old name with the wrong genus, (in this case, Cineraria maritima) becomes a synonym. Finally, the synonym, Centaurea maritima cv. 'Diamond' must be the result of some expert seeing a Senecio cineraria and thinking it was a cultivar of Centaurea maritima, a different, but similar looking species.
If you still haven't had enough about plant taxonomy, check out the Floridata What's in a (Plant) Name Fact Track!
Juice from the leaves and flowers has been used to make eye drops for treating cataracts (not recommended!) Senecio cineraria contains poisonous alkaloids and should not be eaten.
Steve Christman 11/26/99; updated 11/14/03, 2/4/05