As we enter the last months of summer, the thought of doing another seed sowing of flowers is far from the minds of most gardeners. Not necessarily where herbaceous perennials are concerned. In fact, fall seeding can be used to great advantage by the home gardener. Herbaceous perennials differ from annuals in their ability to withstand the winter and return each year from the same roots. In actuality, many of them are not just withstanding adverse conditions, but have evolved to require them.
Perennials drop seeds at different times throughout the growing season, depending upon the species.
The fate of those seeds usually follows one of two directions. With some species, the seeds may remain in the soil throughout the winter and germinate in spring. Other species produce seeds that germinate shortly after falling to the ground. The seedling grows several leaves before the onset of winter, but does not flower. Those seeds that wait until spring to germinate generally require cold, moist conditions of winter to erode the seed coat and allow development of the interior seedling.