Gardener and author Amy Goldman has been growing heirloom tomatoes for 35 years. For her latest book, she tested more than 1,000 varieties of heirloom tomatoes to find the 200 most historic, flavorful and unusual tomatoes in the world. Dr. Oz talks with Amy about her book The Heirloom Tomato: From Garden to Table, the characteristics of heirloom tomatoes and advice on how to grow them.
The difference between an heirloom tomato and an average tomato is that an heirloom breeds true, producing offspring like itself. "Many heirlooms [tomatoes] are oldies but goodies—family heirlooms that have been passed down from generation to generation—but some of them are of a more recent vintage," Amy says.

Another characteristic of heirloom tomato plants is that they grow very large, giving them a larger leaf-to-fruit ratio. The large plant also funnels more sugar and flavor into the fruit. "That's one of the secrets as to why heirloom tomatoes are more flavorful," Amy says.

Amy offers advice on how to help mature your tomato garden:

• Control germination. Start growing your seeds inside in sterile potting soil about four to six weeks before the last frost date in spring, which is the usually the end of April or May 1, Amy says. She also says to give them enough water and keep them in the dark.
• Plant your tomatoes in full sun. Also, Amy says to make sure you're using fertile soil.
• Spacing is key. Heirloom tomato plants need to be spaced widely. She recommends 5 feet between plants and 7 feet between rows.
• Stake or cage your tomatoes. They grow faster, produce more fruit and are less disease-prone if they have air circulation and full sun, Amy says.