what are heirloom seeds?

heirloom vegetable is a cultivar that was commonly grown during earlier periods in human history, but which is not used in modern large-scale agriculture.

Seed Savers Exchange defines an heirloom as any garden plant that has a history of being passed down within a family, just like pieces of heirloom jewelry or furniture. Some companies have tried to create definitions based on date, such as anything older than 50 years.

Heirloom seeds are open-pollinated plants, relying on insects, birds and wind rather than on human intervention. Heirloom seeds, because of their open-pollination characteristic, produce true to their parent unlike seeds from hybrids or genetically modified seeds. Therefore, heirloom seeds can be saved to plant the following year.