Anyone with a gardener in the family tree can probably relate a story of a flower or vegetable variety prized by a grandparent, aunt, uncle, or other relative. But until recently, those old-fashioned plants were not widely available. Interest in heirloom varieties, including tomatoes, has increased in the past few years. Today, many gardeners are attracted to heirloom tomato plants for the diversity of color, flavor, and plant type. If you've never considered an heirloom tomato plant, you might want to try one. Here are some basics to guide you.
To better understand how to grow heirloom tomato plants, you must first know a little about tomato reproduction. An open-pollinated (OP) tomato variety breeds true from seed, meaning the seed saved from the parent plant will grow offspring with the same characteristics. OP seed is produced by allowing a natural flow of pollen between different plants of the same variety.
Heirloom tomatoes are more easily described by what they are not. Most heirlooms predate the 1950s and are OP, meaning they are not hybrids. Seed Savers Exchange in Decorah, Iowa, 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. "They've been handed down from generation to generation," says Kelly Tagtow, marketing manager at Seed Savers Exchange. Preventing cross-pollination and maintaining varietal purity is the primary work of companies such as Seed Savers Exchange.
All heirlooms and OP plants can and do cross-pollinate. And to confuse things further, while all heirlooms are open-pollinated, not all OPs are heirlooms. A hybrid variety, on the other hand, does not breed true from seed; hybrid seed is produced by crossing two different parent varieties of the same species. Hybrids do not remain true in generations after the initial cross and cannot be saved from generation to generation unchanged; most of the mass-market tomato plants are in this category.
It depends. Some heirloom tomatoes have a long, traceable history. For example, one seed saver donated an heirloom tomato, 'Emmy', to Seed Savers Exchange; it is named for a woman who fled Romania after World War II with one of her Transylvanian tomatoes. The beefsteak-size 'German Pink' tomato from Seed Savers Exchange was brought from Bavaria in the 1880s by cofounder Diane Ott Whealy's great-grandfather.
As with growing mass-market tomatoes, gardeners in northern climates will have more success growing heirloom tomato plants if they start seeds indoors or plant seedlings. Once established, most heirlooms are indeterminate, which means they will continue to grow throughout the summer and will produce fruit continually. "Indeterminate tomatoes aren't nice, compact plants," Tagtow says. "If you want them to grow upright, you have to stake them."
For gardeners who are growing heirloom tomato plants, the big surprise often comes with their uniqueness: colors from yellow to orange to red to purple; flavor that's inexplicably complex and rich; and literally thousands of kinds of tomatoes to grow. Seed Savers Exchange alone has 70 in its catalog and 4,000 varieties in its member exchange. If you grow a particular heirloom that you like, you can save its seeds at season's end. And perhaps most importantly, if your heirloom tomato has been grown historically in your region, you can expect a plant well suited for your garden. "It's a unique look and taste and texture that you can't find in most grocery stores," Tagtow says.
But be warned: Just because you are growing heirloom tomato plants doesn't mean they'll be resistant to disease. For example, many hybrid tomatoes have an inbred resistance to tobacco mosaic disease, but heirlooms don't.
If you are interested in growing heirloom tomato plants, many independent gardening stores sell heirloom tomato seeds, and companies such as Seed Savers Exchange have them available to order.