Cultivated seeds, removed from nature, are removed from the natural processes they would be undergoing in the passage of the seasons and may require artificial stimuli to overcome dormancy. Scarification is the abrasive processes that some hard-coated seeds undergo in natural soils or the digestive tracts of birds and mammals; while stratification describes the warm moist conditions preceded by cold moist conditions seeds experience when left on the ground through the winter.
In this video, Adrianna Vargo, nursery manager of the Thomas Jefferson Center for Historic Plants at Monticello, in Charlottesville, Virginia, demonstrates a couple of techniques you can use to emulate these conditions before sowing the seeds.
For more on starting seeds read her article 10 Seed-Starting Tips in the January/February 2003 of Fine Gardening (#89).
Find links to articles, blog posts, and videos on starting vegetable and flower seeds: All About Starting Seeds