Annual
Dusty Miller
Jacobaea maritima · Asteraceae
Also called: Silver Ragwort, Senecio cineraria (former name), Silver Dust
Dusty Miller (Jacobaea maritima) is a low-water annual well suited to Tucson and the low desert. It grows to 8-18 in tall and 12 in wide in full sun to part shade, with a slow to moderate growth rate.
Dusty Miller at a glance
- Water use
- Low (established)
- Sun
- Full sun to part shade; silvery foliage holds color best in full sun. In Tucson, tolerates afternoon shade in peak summer.
- Mature size
- 8-18 in tall and 12 in wide
- Growth rate
- Slow to moderate
- Bloom
- Insignificant mustard-yellow flowers (grown for silver-white felted foliage), Grown for foliage, not flowers; small yellow flowers appear in late spring/summer and are usually removed
- Cold hardiness
- Frost-hardy to roughly 15-20 F; in Tucson 9a-9b it survives winters and is used as a cool-season bedding plant, often persisting as a short-lived perennial before declining in summer heat.
- Soil
- Needs well-drained soil; tolerates poor, sandy, alkaline Tucson soils. Sharp drainage is essential to prevent root and crown rot.
- Native range
- Mediterranean region (coastal southern Europe)
- Best used as
- Silver foliage contrast/edging, Cool-season bedding, Container 'filler/spiller', Borders and mixed plantings
- Wildlife
- Low wildlife value; deer- and rabbit-resistant due to fuzzy, bitter foliage. Minor pollinator interest if allowed to flower.
- Toxicity
- Toxic if ingested—contains hepatotoxic pyrrolizidine alkaloids that can cause liver damage in pets, livestock, and humans. Mildly toxic to cats and dogs (vomiting, diarrhea); keep away from pets, children, and grazing animals. Sap may irritate skin.
How to grow Dusty Miller in Tucson & the low desert
Watering
Grown primarily as a cool-season annual in Tucson: plant in fall (October-November) for winter and spring foliage display. Water moderately to establish, then sparingly—it is drought-tolerant and prone to rot in wet, poorly drained soil. Water weekly in winter, more in spring warm-up.
Fertilizer & nutrients
Very light feeder; needs little fertilizer. A single light application of balanced slow-release feed at planting is ample. Over-fertilizing reduces the prized silvery leaf color.
Pruning & care
Pinch tips to keep compact and bushy; remove any yellow flower buds (insignificant) to keep the plant focused on foliage. Shear leggy plants to rejuvenate.
Notes
Best used in Tucson as a fall-through-spring foliage accent; it struggles and often dies out in the intense summer heat, so treat as a cool-season annual. Its silver leaves pair well with cool-season flowers like petunias, snapdragons, and pansies. Prized for color and texture rather than bloom.
Sources: University of Arizona Cooperative Extension; Pima County Master Gardeners; Merck Veterinary Manual (toxicity); Missouri Botanical Garden