Types of daylilies: tetraploid vs diploid, miniature to large

Daylilies (*Hemerocallis* spp. and hybrids) are among the most adaptable perennials available to temperate gardeners. They are genuinely low-maintenance once established, tolerant of drought and poor soil, and bloom prolifically. Over 80,000 registered cultivars.

Daylilies (Hemerocallis spp. and hybrids) are among the most adaptable perennials available to temperate gardeners. They are genuinely low-maintenance once established, tolerant of drought and poor soil, and bloom prolifically. Over 80,000 registered cultivars exist.

Despite the name, daylilies are not true lilies (Lilium spp.). Each flower opens for one day only, but each scape (flower stalk) produces 12–30 buds that open in succession over a 2–4 week period.

Diploid vs. tetraploid: the most misunderstood distinction

Per Missouri Botanical Garden, diploid daylilies have the standard two sets of chromosomes (2n=22); tetraploids were created by treating diploid seedlings with colchicine, which doubles the chromosome count (4n=44).

The effects:

• Tetraploids have larger, heavier, more formally shaped flowers with thicker petals
• Flower colors are typically more saturated in tetraploids
• Stems are thicker and scapes are more upright
• Many modern show-quality cultivars are tetraploids
• Diploids often rebloom more freely and are more suitable for naturalizing

Neither type is categorically superior — the choice depends on whether you want formal display (tetraploid) or prolific naturalized blooms (often diploid).