Scarification of Seeds

Scarifications of seeds: Seed scarification was really easy to remember once I remembered that what you're doing scarring seeds. A seed's hard outer coat makes it impervious to gases and moisture that would cause them to germinate. To overcome this you need to scratch, break or nick the seed coat. In nature this naturally occurs when seeds pass through the digestive tract of some animals, through freezing temperatures or microbial activities that break down the seed coat. Seeds that need to be scarified before sowing are usually large or have thick seed coatings like seeds in the morning glory family, runner beans like purple hyacinth beans vine or canna seeds.
--from Mrbrownthumb.blogspot.com