Dutch Iris: How Much Cold It Needs and How Long It Lasts
Dutch Iris bulbs need 4 inches of soil, 4 inches of space from their neighbors, and 8-10 weeks below 45F to bloom at all.
Home & garden, state by state
Dutch Iris bulbs need 4 inches of soil, 4 inches of space from their neighbors, and 8-10 weeks below 45F to bloom at all.
Daffodils need 12 to 16 weeks of temperatures below 45°F to bloom, they thrive in USDA zones 3 through 8, and the bulbs go in the ground 6 inches deep…
Crown Imperial needs 12-14 weeks of temperatures below 45F to bloom, and it only thrives in USDA zones 5-8.
Crocus corms need 8 to 15 weeks below 45F before they’ll flower, and they’re hardy across USDA zones 3 to 8.
Camassia asks for one thing most spring bulbs don’t demand as strictly: a long, cold winter.
Asiatic lilies need a genuine winter to bloom right, and how you plant them decides everything else.
Ornamental Allium needs 12 to 14 weeks below 45F to flower properly, and it only performs reliably in USDA zones 4 through 8.
Florida’s zones run 8b to 11b, and Jacksonville’s NOAA climate normals show heat load, not winter cold, decides which flowers survive.
Florida sits mostly outside the cold that spring bulbs need to flower, and that single fact decides more than any planting date.
Delaware’s humid summers and zone 7a-8a winters favor native perennials like coneflower and daylily, while tropical annuals and thirsty exotics often struggle.