Horticultural Classification
In horticulture, tulips are divided up into fifteen groups (Divisions) mostly based on flower morphology and plant size.
- Div. 1: Single early – with cup-shaped single flowers, no larger than 8 cm across (3 inches). They bloom early to mid season. Growing 15 to 45 cm tall.
- Div. 2: Double early – with fully double flowers, bowl shaped to 8 cm across. Plants typically grow from 30–40 cm tall.
- Div. 3: Triumph – single, cup shaped flowers up to 6 cm wide. Plants grow 35–60 cm tall and bloom mid to late season.
- Div. 4: Darwin hybrid – single flowers are ovoid in shape and up to 8 cm wide. Plants grow 50–70 cm tall and bloom mid to late season. This group should not be confused with older Darwin tulips, which belong in the Single Late Group below.
- Div. 5: Single late – cup or goblet-shaded flowers up to 8 cm wide, some plants produce multi-flowering stems. Plants grow 45–75 cm tall and bloom late season.
- Div. 6: Lily-flowered - the flowers possess a distinct narrow 'waist' with pointed and reflexed petals. Previously included with the old Darwins, only becoming a group in their own right in 1958.
- Div. 7: Fringed (Crispa)
- Div. 8: Viridiflora
- Div. 9: Rembrandt
- Div. 10: Parrot
- Div. 11: Double late - Large, heavy blooms. They range from 18-22 in. tall
- Div. 12: Kaufmanniana - Waterlily tulip. Medium-large creamy yellow flowers marked red on the outside and yellow at the center. Stems 6 in. tall.
- Div. 13: Fosteriana (Emperor)
- Div. 14: Greigii - Scarlet flowers 6 in. across, on 10 in. stems. Foliage mottled with brown.
- Div. 15: Species (Botanical)
- Div. 16: Multiflowering – not an official division, these tulips belong in the first 15 divisions but are often listed separately because they have multiple blooms per bulb.
They may also be classified by their flowering season:
- Early flowering: Single Early Tulips, Double Early Tulips, Greigii Tulips, Kaufmanniana Tulips, Fosteriana Tulips, Species Tulips
- Mid-season flowering: Darwin Hybrid Tulips, Triumph Tulips, Parrot Tulips
- Late season flowering: Single Late Tulips, Double Late Tulips, Viridiflora Tulips, Lily-flowering Tulips, Fringed Tulips, Rembrandt Tulips
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