Starting seeds off in pots is one way to do it. Alternatively "direct sow" i.e. straight into the ground where the plants are intended to grow as I did today. The white flowered form of Honesty (Lunaria annua alba) is generally biennial but sometimes flowers the year after sowing. Hedge Woundwort (Stachys sylvatica) is perennial but grows fast and can be in flower the following year.

 Some gardening books recommend propagating seeds in spring as the most reliable approach. Fair point but if a plant sheds seed in autumn then an autumn sowing is simply following nature's course.