Several years ago I grew interested in primulas and now have several types in my garden. But one type continues to cause me problems: candelabra primulas. I grew several, they were pretty, but they did not overwinter. And my efforts in successive years to germinate their seeds have been total failures. Right now I have seedlings of three types of primulas growing well. And primulas planted in previous years are starting to bloom. But my candelabra primula seeds refuse to germinate, whether kept at room temperature or outdoors. Do they have some special requirements that other primulas do not have?