2. In science, dormancy describes the temporary suspension of visible growth of any plant structure containing a meristem*. The term “dormant” is not restricted to deciduous plants but also applies when plants that retain some, or all, of their foliage suspend growth and have dormant buds (e.g. most coniferous trees, rhododendrons in winter). All daylilies, regardless of registered foliage habit, suspend growth when it gets cold enough.
* Reference: Lang et al, “Endo-, Para-, and Ecodormancy: Physiological Terminology and Classification for Dormancy Research”, HortScience, Vol 22(3), June 1987.