The plant is a tender perennial that is generally only winter-hardy in zones 8 to 11 but sometimes it survives the winter in colder climates. Otherwise, it is grown as an annual. Sow seeds in the ground after the spring frosts and expect seedlings in two to three weeks. Seedlings turn into rounded mounds of foliage that grow to about 1 foot tall the first year. Dusty miller is toxic to humans, dogs, and cats. Silver dust is one of those plants that is full of surprises. It sometimes survives the winter in zones colder than its usual hardiness zones. Gardeners report plants coming back in zone 5 or even zone 4 landscapes. Another surprise is that yellow flowers may make an appearance in the second growing season of silver dust. Silver dust is not marketed as a blooming plant, and while not all plants will produce the yellow fuzzy flowers, they increase the beauty of mature plants.
Light
Silver dust needs full sun to stay compact and keep their fabulous foliage color. Plants growing in shade are leggy and produce fewer of the hairs that give them their silvery color.
Soil
Silver dust plants adapt to a variety of soils, but good drainage is key for healthy plants. Whether your soil is on the rocky side or is characterized by clay, you can improve both your pH (it prefers a range of 5.5 to 6.0) and drainage by amending it with compost.
Water
The fuzzy growth that gives silver dust its sheen also helps plants stand tall in periods of drought. Like other plants that hail from Mediterranean climates, silver dust can get by with occasional watering once it is established. A layer of organic mulch will make plants even less dependent on supplemental irrigation. One inch of water per week is enough to keep silver dust growing strong. It does not like soggy conditions.
Temperature and Humidity
As a Mediterranean plant, silver dust thrives in hot, sunny climates. Excessive humidity isn’t a problem as long as plants have adequate spacing and a position in full sun.
Fertilizer
Silver dust plants are light feeders, and only need supplemental fertilizers in areas with very poor soil. In this case, it’s better to feed and improve the soil at the same time by adding organic matter like well-rotted manure or leaf mold.
Silver Dust Varieties
The difference between silver dust cultivars can be seen in how dissected the foliage is. Some varieties are very lacy and fine, while others are only slightly lobed.
‘Cirrus’: Broad leaves with scalloping on the edges adorn this variety.‘Silverado’: The fern-like foliage is popular in many gardens.‘Silver Lace’: This variety has very fine foliage, as the name implies.
Pruning
Silver dust plants require no pruning to maintain their pleasing bushy shape. If you feel that the yellow blooms detract from the plants, shear them off as they appear.
Propagating Silver Dust
You can propagate silver dust by cuttings in the spring when plants are putting out the most rapid new growth.
How to Grow Silver Dust From Seed
Fill your garden beds with silver dust by starting a flat of seeds six weeks before your average last frost date. Cover seeds lightly with sterile potting mix, and grow at 70 degrees Fahrenheit. You will start to see germination in about 10 days. Plant outdoors 8 inches apart in pots, or 10 inches apart in the ground.
Potting and Repotting Silver Dust
Silver dust looks fantastic in all kinds of containers, including hanging baskets and window boxes. The finely divided foliage looks so pretty combined with the trailing stems of petunias or million bells, and also makes a handsome companion plant for other sun lovers like zinnias, pentas, or salvia. Keep your container in full sun, and water more frequently than plants growing in the ground, at least every other day in summer. Pot up silver dust with any commercial potting soil. Make sure your container has drainage holes. Add a handful of peat moss to increase acidity. A layer of mulch on the soil will retain water and keep the soil from splashing onto the leaves. It’s time to repot when you see roots coming out of the drainage hole.
Overwintering
Silver dust is tolerant of cold weather within its hardiness range, but you can reduce watering in the late summer to ready it for winter. Prune it back with sharp and sterile shears to just above ground level and mulch with pine needles or straw.
Common Pests & Diseases
Slugs enjoy snacking on silver dust plants, especially in flowerbeds that receive frequent irrigation. Handpick the pests, or use beer traps to control their numbers. In addition to attracting slugs, excessive watering can cause root rot in silver dust plants. This is more of a problem in clay soils. In areas with heavy soil, you can prevent it by growing your silver dust plants in containers or raised beds.
