Evergreen daylilies typically keep their foliage year ‘round in warmer climates. This doesn’t mean they bloom all year. They only flower during bloom season, but if you live in an area that doesn’t get freezing weather (zones 8-10) they will probably keep their leaves all year. If you live in a colder area (zones 7 and colder), though, the foliage will be bitten back in the winter.
What does this mean? Everyone can grow Evergreen or Semi-Evergreen daylilies. But only growers in the warmest zones will actually have foliage in the winter.