Last summer I grew a tomato variety called “Giant Belgium.” At its late-summer peak, the plant was loaded with 37 ripe tomatoes and each fruit weighed more than 1 pound.

Several weeks ago, when my brother dropped off his leftover tomato seedlings, I glanced through the plants to see if any were labeled Giant Belgium. Fortunately, the collection included one Giant Belgium, which I promptly planted in the same spot as last year.

Giant Belgium is classified as an “heirloom.” Heirlooms are open-pollinated plants that have been cultivated and their seeds passed from generation to generation for decades or even hundreds of years. 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.”

Insects, hummingbirds or wind fertilize open-pollinated flowers of heirloom plants. Resulting seeds produce plants that are identical or very similar to the parent plant. Contrast this with hybrid plants, which won’t breed true from seeds collected from the hybrid plants.

Through the centuries, people selected and conserved seeds from plants with excellent flavor, vigor, scent and/or hardiness. Heirloom seeds were often among the few belongings immigrants brought to America. Many heirloom plants are still being passed back and forth among friends and families and some are packaged for sale to gardeners.

Interest in and cultivation of heirlooms is on the rise. People are rediscovering that heirlooms offer great diversity in flavor, color, texture, fragrance, size, form and shape, not only in vegetables but also in flowers and herbs.

Starr Carpenter, a Chisago County Master Gardener, says she has grown more than 100 varieties of heirloom tomatoes. “When I started this, I had no idea there were so many varieties available. Some are very similar, but for the most part, the shapes, colors and flavors of heirlooms are amazing -- green, black, yellow, orange, white, striped, miniature beefsteak, plum, cherry, currant, oxheart, sausage and hollow stuffers.”

Carpenter has three favorite heirloom tomato varieties: Black Plum, a dark-red, pear-shaped, almost blemish-free variety; Moskvich, a medium-sized bright-red tomato with the flavor of brandywine; and Green Zebra, a green-with-yellow-stripes tomato with “the most intense tomato flavor I have ever tasted,” she says.

To learn more about heirloom vegetables, flowers and herbs, a good place to start is the non-profit organization called Seed Savers Exchange (www.seedsavers.org). SSE was founded in 1975 by Diane and Kent Whealy after Diane’s terminally ill grandfather gave them the seeds of two garden plants, Grandpa Ott's morning glory and German Pink tomato. The grandfather’s parents brought the morning glory and tomato seeds from Bavaria when they immigrated to St. Lucas, Iowa in the 1870s.

SSE bills itself as America’s premier source for heirloom seed. According to its website, more than 24,000 rare vegetable varieties are being permanently maintained at the 890-acre Heritage Farm near Decorah, Iowa. The collection includes 4,000 traditional varieties from eastern Europe and Russia.

Two other websites with heirloom seeds and catalogs are www.rareseeds.com and www.selectseeds.com.     

One interesting page on the selectseeds.com website is a list of more than 80 annuals, perennials and biennials that are said by the company to be “deer-resistant and deer-repelling.” Based on the number of complaints I hear every year from gardeners who have their plants decimated by deer, this might be a list worth reviewing.

This website also contains useful guidelines on preparing and planting your garden, and growing flowers from seed.

The rareseeds.com site includes a link to a gardening forum called www.idigmygarden.com, “the hip community of heritage gardeners, natural foodies and seed savers.” Many of the postings are thoughtful, educational and entertaining.

Many seed companies today sell primarily hybrid plants and seeds, which offer many desirable traits but also require that gardeners purchase new seeds and plants each gardening season. An advantage of heirlooms, therefore, is plants that produce seeds that can be collected and re-planted the following growing season. “An entire generation of gardeners grew up believing that all tomatoes were red, round and identical in taste,” states the SSE website. “Heirloom gardening is putting an end to that myth!”