Check the annual "best bets" recommendations made by state university extension services, independent organizations, and national horticultural societies. "Our testing process is looking for the varieties that are truly superior in their performance," says Nona Koivula-Wolfram, AAS executive director. Each year, flower and vegetable seeds are grown in test plots across the US. The best receive AAS status. For 2007, three flowers – a celosia (Fresh Look Gold), a petunia (Opera Supreme Pink Morn), and a vinca (Pacifica Burgundy Halo) – and a pepper (Holy Molé) were chosen. But even a recommended plant can falter, given the conditions in your garden and quirks in soil, light, and temperature.
Keeping this in mind, it's still possible to choose plants from several basic categories, from roses to lettuce, with some degree of assurance of their success.
Roses: color may vary by climate
Regional soil and climate differences can alter a rose's color, says Bill Riddle, American Rose Society consulting rosarian in Columbus. West Coast judges working at Midwest shows occasionally seek to disqualify an entry because it doesn't look like the California-grown blossom.
Vigor is also affected by microclimates, areas where the soil may be wetter, drier, warmer, or cooler than the surrounding garden because of wind protection or sunlight reflecting off of a structure. Some of Mr. Riddle's AARS plants, for example, may fare better than those grown a few miles away in the Columbus Park of Roses, one of the nation's largest public rose gardens.
Giving new plants a couple of years to become established can improve a so-so performer. "The second year it might knock your socks off," says Tom Wood, also a Columbus-area rosarian.