By definition, perennials are herbaceous plants that come back year after year. But they don't come back every year forever. Some, like the peony, become fixtures in the landscape, easily living for 25 to 50 years or more and becoming landscape plants that get inherited from one generation of homeowners to the next. Others, like lupine and wallflower, call it quits after three to five years.

There's nothing wrong with that, the glass-half-fulls among us say. If no plants called it quits, there wouldn't be holes in the garden that we can fill with new and interesting plants. But if you honestly plan on planting only once where you can, the best thing to do is dedicate the ground to the long-lived.

But first, a word about good genes. They usually can't overcome an untenable environment. If a plant needs moist shade, putting it in dry sun will usually kill it pretty quickly, regardless of how long it's known to live. And as tough as some plants are, they need a minimal amount of care.

"If you don't divide shasta daisy and give it potassium, it will definitely be short-term," says Ruth Baumgardner, co-owner of Mouse Creek Nurseries in Riceville, Tenn.

Plants like the old-fashioned foxgloves, hollyhock and verbascum seem short-lived, but they're actually biennials. And some plants like blanket flower, lance coreopsis (Coreopsis lanceolata), Leucanthemum and Phlox divaricata may not be long-lived but they reseed.