The Most Vigorous Blooming Day Lilies

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• All day lilies grow quickly, reaching their mature size in only three or four years. Most bloom the first year after planting. Some varieties are more vigorous than others, though. "Stella de Oro" (Hemerocallis "Stella de Oro") has been considered the gold standard for many years, with its prolific bright yellow blooms. It grows in USDA zones 5 through 7. "Happy Returns" (Hemerocallis "Happy Returns"), a descendant of "Stella de Oro," produces yellow blooms from spring to frost. It is adapted to USDA zones 3 through 9. Some day lilies, such as tawny day lily (Hemerocallis), which grows wild in many areas, are so vigorous they become invasive, says Clemson University Cooperative Extension.

Day Lilies for Northern Gardens

• Day lily foliage falls into three categories -- deciduous, semi-evergreen and evergreen. Deciduous types die back in the fall and are best suited for regions with cold winters. Like all day lilies, deciduous day lilies need well-draining soil and sun. Two recommended by the All-American Day Lily Selection Council include "Lemon Lollypop" (Hemerocallis "Lemon Lollypop"), a yellow variety that grows up to 28 inches tall, and "May May" (Hemerocallis "May May"), which has unusual off-white flowers and grows 24 inches tall. Both varieties thrive in USDA zones 5 through 10.

Evergreen Day Lilies

• Although they'll grow in northern climates, semi-evergreen and evergreen day lilies thrive in warm, Southern states. A few, in particular, are known for their beauty and vigorous growth. "Always Afternoon" (Hemerocallis "Always Afternoon") is a winner of the Stout Medal, the highest honor for day lilies. "Always Afternoon" grows 22 inches high and produces lavender, ruffled blooms from early- to mid-summer. Another Stout Medal winner, "Fairy Tale Pink" (Hemerocallis "Fairy Tale Pink") produces soft, ruffled pink flowers that re-bloom and won't fade in the sun. Both plants are adapted to USDA zones 3 through 9. In general, day lilies grow best in full sun but tolerate partial shade, especially in hot climates.

Recommendations

• In addition to vigorous growth and bloom, the ideal day lily plant has several bracts, or flower stems. Foliage should be green and healthy, and the petals should be thick to avoid melting or fading in the heat of the day. Day lilies need almost no maintenance but to ensure the most vigorous plants, select varieties adapted to your region. Day lilies should be planted from divisions or nursery transplants, not seed. Most day lilies bloom for only 30-to-40 days, but you can extend the season from spring to frost by planting several different varieties or selecting ever-blooming types.