Answer: Petunias, cosmos and impatiens are not cold hardy so any plants that germinate in the fall would not survive your cold winters. It is possible that the seeds might survive and sprout in the spring, but they would not do so until the weather had warmed and the soil had warmed. This would mean your plants would be much smaller and later than new transplants that have been started in the greenhouse or indoors. The winter heaving and thawing along with the severe weather conditions may also cause the germination rate to drop substantially. In my experience it is far better to wait until spring.
Q&A Library Searching Tips