There are several varieties of cineraria, from the beautiful, flower-laden houseplant to the silver leaf dusty miller (Centaurea cineraria) found in many landscapes. There is even a cineraria that is a small tree that is grown in India (Prosopis cineraria). The most common, though, are the brilliant flowering houseplant cineraria and the garden variety, dusty miller.
Cineraria is an annual plant that is grown from tiny seeds and usually done in a greenhouse environment because of the seedlings' intolerance for variations in the growing conditions. As a houseplant, the cineraria plant also has specific requirements to keep it happy. Although flowering cinerarias love bright light, they cannot tolerate direct sunlight. This is because the cineraria also thrives in cooler environments in the mid-15.6 degrees C range and direct sunlight it too hot for the plant. Pot them in a peat-based soil that is kept moist, but not overly wet. The cineraria will do well with normal home humidity and does not care to be misted with water. If any of these growing conditions are lacking, your cinteraria will quickly let you know, usually by wilting. Cinerarias generally are not bothered by pests, like whiteflies and aphids, unless the plant is already under stress from another condition. Because cineraria is an annual, after the plant is done blooming, it should be discarded
In the Garden
Planting the cineraria variety known as dusty miller in your garden will add texture and a display of silvery foliage among the green. Although dusty miller can be cultivated from seeds, because, like the cineraria houseplant, dusty miller thrives in cooler temperatures, most gardeners plant purchased seedlings in their gardens in the spring. Plant the seedlings in a well-draining soil that is rich in organic matter. Choose an area that receives bright light, but not direct sunlight which is too hot for the plant. After the seedlings begin to grow, add mulch around the plants to retain moisture in the soil and keep the ground cool. To promote fuller, bushier plants, pinch the flower buds off as they develop. The main pest is the whitefly when the temperature becomes too hot. Powdery mildew and bacteria fungus can attack the plant if the environment is too moist, either from over-watering or humidity. Because the dusty miller is an annual, it will die off after the first frost.