Daylilies (Hemerocallis spp.) are hardy perennials admired for their vibrant blooms and adaptability. Understanding their distinct growth stages throughout the year is helpful for successful cultivation and providing appropriate care as they transition through their annual development.
Understanding Daylily Types
Daylilies are classified into three main types based on their foliage behavior in colder temperatures. Dormant daylilies (DOR) are deciduous; their foliage completely dies back to the ground when frost arrives. Evergreen daylilies (EV) retain their leaves throughout the year in mild climates, continuing to grow unless freezing weather occurs and continually producing new leaves. Semi-evergreen daylilies (SEV) exhibit characteristics between dormant and evergreen types. Their foliage is slower to die back in the fall, and some green shoots may remain visible even after severe cold. In colder climates, semi-evergreens may behave more like dormant types, but in milder regions, they can retain significant foliage.
Annual Growth Cycle: Spring Emergence to Peak Bloom
The daylily’s annual growth cycle begins in spring. New shoots emerge from the plant’s crown, which is the solid white core located between the leaves and the roots. As temperatures rise, the characteristic strap-like foliage rapidly develops, forming dense clumps. This initial period is marked by vigorous growth, as the plant channels energy into establishing a robust leafy structure.
Following foliage development, leafless flower stalks, known as scapes, begin to rise above the leaves. Numerous buds form along each scape, promising a succession of blooms. While individual daylily flowers typically last only one day, each scape produces multiple buds that open on successive days, creating a continuous display over several weeks. This peak blooming period, extending from late spring to summer, represents a significant expenditure of the plant’s stored energy.
Annual Growth Cycle: Post-Bloom to Dormancy
After the peak blooming period, the daylily transitions into its dormant phase. Spent blooms fade, and if not removed, the plant may develop seed pods. Allowing seed pods to form diverts the plant’s energy away from maintaining healthy foliage or producing further blooms. While primary flowering may subside, foliage continues to grow, capturing sunlight to build energy reserves for the following season.
As autumn approaches and temperatures cool, the plant’s energy gradually declines. Foliage may begin to yellow or turn brown, signaling the plant’s preparation for rest. Dormant daylilies’ leaves completely die back to the ground. Evergreen types attempt to retain their foliage through winter, though in colder regions, their leaves may suffer from frost damage. Semi-evergreen varieties will have their foliage partially die back, with some green remaining, or behave like dormant types depending on the climate severity.
Long-Term Growth and Division
Daylilies are long-lived perennials that exhibit ongoing growth, forming larger clumps over time. They grow from a crown, the central growing point from which both roots and leaves emerge. As the plant matures, it produces more “fans” or individual plant units, leading to a denser, more expansive clump. This natural clumping habit means daylilies can remain in the same location for many years, often reaching mature size within three to four years.
Eventually, daylily clumps can become overcrowded, which may lead to reduced vigor and fewer blooms. Division becomes necessary to rejuvenate the plants and maintain their flowering performance. This process involves digging up the entire clump and separating it into smaller sections, each with two or three fans and a healthy root system. Division is typically performed in early spring as new growth emerges or in late summer after the flowering period, allowing the plant sufficient time to re-establish before winter.