Continuously blooming daylilies can more accurately be called "continuous rebloomers," as Mike Huben, a breeder from Massachusetts, describes his long-blooming hybrids. Valleybrook Gardens in Canada reports 125 days of flowers from a series of everblooming daylilies bred by the hybridizer Darrel Apps, but that was under test conditions. Frances Gatlin of the American Hemerocallis Society wrote, as of 2004, there was "no such thing as an everblooming daylily." Whatever the consensus, there are certainly long-bloomers out there to try.
Stella De Oro
Walter Jablonski, an Indiana daylily breeder, hybridized the Stella de Oro daylily (Hemerocallis 'Stella de Oro') in the 1970's. The Stella daylily was the first of the long-blooming daylilies. It may have the capacity for flowering from spring to frost, but not according to Mike Huben, who didn't have a rebloom for three years.
The Stella daylily is short--up to 12 inches--and has small gold flowers beginning in spring. Frances Gatlin says it may need dividing every few years to keep it blooming reliably.
The Happy Returns daylily (Hemerocallis 'Happy Returns') was the first in a series of everblooming daylilies from Darrel Apps. Since it first became widely available, it has given Stella's popularity a run for its money. It starts blooming in early summer and its lemon-yellow color is easier to fit into a garden color scheme than the gold Stella. After its first flush of flowering, be sure to remove the spent flowers to prevent seed from forming. Otherwise, flowering will stop to help produce seed. 'Happy Returns' is short, to 14 inches.
The Rosy Returns daylily (Hemerocallis 'Rosy Returns') is descended from Happy Returns, as the name suggests. Valleybrook Gardens mentions that Darrel Apps was the first to isolate the everblooming gene in the daylily. With Rosy Returns, he continues that achievement. This daylily starts blooming later than Happy Returns and goes to early fall. Its color is a brownish pink that can look muddy, but its qualities of long-blooming make it a good one to grow. Rosy Returns grows to 21 inches.
Ruby Stella (Hemerocallis "Ruby Stella') is a red version of Stella de Oro. Valleybrook Gardens lists it as an introduction from Europe. It has some fragrance and blooms early, then continuously until fall. It grows to 21 inches.
A Darrel Apps hybrid, Red Hot Returns (Hemerocallis 'Red Hot Returns') is a red daylily with a yellow throat. Its flowers, according to Valleybrook Gardens, are five inches across. It flowers from June until frost. It grows to 23 inches.
Mike Huben's Snowy Stella (Hemerocallis 'Snowy Stella') is a near-white continuous re-bloomer introduced in 2007. It is shorter than Stella de Oro and it starts blooming a week later. The blooms are similar in size but there are more per stem. Huben admits it is not totally white; he's still on the quest. It has a touch of apricot in it. Harmon Hill Gardens in New Hampshire and Partridge Gardens carries this daylily, but it is expensive.