Cineraria is a seasonal bloomer that generally flowers 16 to 18 weeks after seeds germinate and sprout. Thus, it's easy enough to dictate the bloom period by choosing the proper time to plant the seeds. For Christmas bloom, for example, you should plant seeds in late August to early September. Remember, though, that it's tricky to provide the proper cool and humid conditions when growing this plant indoors. This is why many people seeking winter-blooming plants simply buy them in season from a houseplant supplier.