In reply to Kemics:
It's usually the photoperiod that triggers plants different growing stages. My parents used to have Geraniums indoors all year without a problem, though I don't remember them growing from seed during winter. You can easily fool the plants by putting them somewhere where they get at least 12 hours of light, ideally up to 18 for best growth. If you can manage to have them near a window during the day and give some fairly bright artificial light in the evening they should grow quite happily.
Post edited at 20:07