Daylilies are herbaceous perennials belonging to the lily family (Liliaceae). The scientific name, Hemerocallis, combines two Greek words that mean "beauty" and "day," referring to the fact that daylily flowers bloom for just a single day. Numerous buds sprout on each flower stalk, however, so the blooming period typically lasts for several weeks. Many daylily varieties are diploids, which means they have a pair of identical chromosome sets in each cell. The following diploid daylilies are all vigorous varieties winter hardy in USDA zones 3 to 9.
The Happy Returns daylily is a diploid variety often planted as borders, container plants and edging plants. This repeat-blooming variety bears lemon yellow flowers from June through the first frost. The ruffled, 3-1/2 inch flowers bloom on otherwise bare stems that reach up to 1-1/2 feet in height. This mildly fragrant daylily prefers well-drained soil in fully sunny to partly shady locations.
Prince of Venice
Prince of Venice daylilies are evergreen in the warmer southern climates. This diploid cultivar features mauve to wine flowers with yellow-green throats. These 5-inch flowers bloom in June and July. The Prince of Venice daylily generally reaches heights ranging from 2 to 2-1/2 feet. These daylilies prefer rich, loamy soils but adapt well to other soil conditions. This variety is often used for ground covers and borders.
The Purple d'Oro daylily is a miniature diploid variety that tolerates hot temperatures and high humidity levels. This plant features ruffled, red-purple flowers with yellow throats. Purple d'Oro plants reach up to 2 feet in height with similar spreads. This repeat-blooming daylily first blooms in May and typically continues through the end of August. The fountain-like foliage makes the Purple d'Oro variety a common choice for mass plantings and ground covers.
The Autumn Minaret daylily is one of the larger diploid varieties, often reaching up to 6 feet in height and 3 feet in width. This variety blooms 5 inch flowers with orange-yellow or gold petals surrounding a rust-colored center disk. These fragrant flowers generally bloom in June and July. Autumn Minarets add vibrant color to perennial borders and ground covers.
The Joan Senior daylily is an American Horticultural Society (AHS) award-winning variety that prefers medium soils in fully sunny to partly shady planting sites. This diploid daylily blooms white flowers featuring bright green throats. The plants typically reach heights of 1-1/2 to 2 feet with similar spreads. This low-maintenance daylily is often used for borders and ground covers.
Going Bananas is a diploid daylily similar to the Happy Returns variety. This daylily typically grows between 1-1/2 and 2 feet high with a similar spread. The overlapped petals are a light yellow color and feature green throats. Each stem produces between 10 and 15 flowers each blooming season. The first bloom typically occurs in June with a rebloom period lasting into the autumn months.
Pink Super Spider
The Pink Super Spider is a diploid daylily variety that blooms large flowers in June and July. The 10 inch flowers have pink to rose petals with green-colored throats. The thin petals are much longer than they are wide. This spider lily grows to 3 feet in height with spreads about 2 feet. The Pink Super Spider is commonly used for ground covers and borders.