The definition of heirlooms is less cut-and-dried. With seed-grown plants, only open-pollinated varieties are considered heirlooms. Unlike hybrids, open-pollinated seeds will reproduce true to type, meaning the offspring will display the same characteristics as the parent plant, and seeds can be saved from season to season. Since a conclusive definition for heirloom seeds and plants doesn't exist, I turned to Peggy Cornett, director of the Thomas Jefferson Center for Historic Plants, for her interpretation of the term. "I consider plants heirlooms if they were once significant in gardens but are now rare or even extinct in cultivation," says Cornett. "For example, there are many cultivars of iris or phlox or daylilies from the early 20th century that are nearly impossible to find." Seeds are generally considered heirlooms if they were introduced into cultivation at least 40 years prior to the current date, though some heirloom experts consider seeds heirlooms only if they were introduced prior to World War II.
Gardening organically goes hand in hand with growing heirlooms, since many heirlooms were introduced into cultivation before synthetic fertilizers and pesticides became available. Home gardeners play a very important role in the preservation of heirlooms. "Many people preserve special plants and pass them down from one generation to the next along with the stories and histories surrounding these heirlooms. When we lose that essential connection, its often lost forever," Cornett says. If you're interested in growing and preserving heirlooms, you'll find many resources to explore, including Monticello's Web site (www.monticello.org), Seed Savers Exchange (www.seedsavers.org), and William Woy Weavers book Heirloom Vegetable Gardening (Henry Holt and Company, 1999).