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Bulbs and Bulb Planting Times
Planting Spring-Blooming Bulbs
On this page you’ll find specific details about timing the planting of spring-blooming bulbs in different climate areas of the United States, including :
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- Climate and condition factors that affect bulb planting times
- Lifecycle of spring-blooming bulbs and climate effects on planting
- How temperature and precipitation impacts bulb bloom cycles
- Map of bulb-planting regions of the United States
- Planting recommendations and suggestions by region
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Regional Differences and Bulb Planting Times
Within the large landmass of the United States, both the length, severity, and depths of extreme cold and the nature of summer heat define regional differences in bulb planting times.
Some areas also have prolonged periods of summer without precipitation, a climate called Mediterranean that affects dormancy in spring-blooming bulbs. Others receive precipitation throughout summer, requiring lifting of spring bulbs after bloom to force dormancy and avoid fungal disease losses.
To aid gardeners, the Netherlands Flower Bulb Information Center has created a map showing each of these regions and provided guidance on planting spring-blooming bulbs. You’ll find their map and its legend information here.
Why Regional Differences Matter for Bulbs
Bulbs and other bulbous plants evolved to quickly grow, flower, and reproduced during short periods of favorable weather conditions. Heat, cold, or drought causes them to become dormant, reserving their energy for the next favorable weather period.
Prior to entering dormancy after a bloom cycle, the bulb’s roots store nutrients in specialized root structures. This feature sets bulbous plants apart from other perennials and herbaceous plants.
It’s desirable when planting bulbs to set them into soil while they are fully dormant, giving them an opportunity to establish roots, and then wait for favorable weather. For most of the spring-blooming species—in most regions—this means setting out bulbs in autumn after soils cool but before freezes or frosts occur.
Some regions have neither freezes—they’re subtropical areas—or severe winters—including coastal regions and areas of the South in the United States.
In these areas, planting too early in autumn risks early sprouting and premature blooms while daylight hours are still short, preventing the bulbs from storing sufficient energy in their roots. They may die out in such regions after a few seasons.
Follow the regional planting map provided to set out bulbs in your landscape for best chances of success.
Your Bulb Planting Region
United States Bulb Planting Regions
Using the Bulb Planting Regions Map for Spring-Blooming Bulbs
Find your region and click on Read More (below) to find your U.S.D.A. Plant Hardiness Zone and the best time to plant spring-blooming bulbs in your home’s landscape.
There are significant differences in planting times for bulbs with different seasons of bloom [see: Bulbs and Seasons of Bloom].
A. New England—USDA Plant Hardiness Zones 3, 4, 5. Optimum planting time: September 15–November 15.
B. Mid-Atlantic Coast—USDA Plant Hardiness Zones 6, 7, 8. Optimum planting time: October 1–November 30.
C. Appalachia—USDA Plant Hardiness Zones 5, 6. Optimum planting time: September 15–November 30.
D. South Atlantic Coast—USDA Plant Hardiness Zones 7, 8. Optimum planting time: October 15–December 15.
E. Great Lakes—USDA Plant Hardiness Zones 5, 6, 7. Optimum planting time: September 15–November 15.
F. East Central—USDA Plant Hardiness Zones 5, 6, 7. Optimum planting time: October 1–November 30.
G. South Central—USDA Plant Hardiness Zones 7, 8. Optimum planting time: October 15–December 15.
H. Tropical—USDA Zone 10. Optimum planting time: December 1–January 15.
I. Gulf Coast—USDA Plant Hardiness Zones 8, 9. Optimum planting time: October 1–December 31.
J. North Central—USDA Plant Hardiness Zones 3, 4, 5. Optimum planting time: September 15–November 1.
K. Central Great Plains—USDA Plant Hardiness Zones 5, 6. Optimum planting time: September 30–November 30.
L. Rocky Mountains—USDA Plant Hardiness Zones 2, 3, 4. Optimum planting time: September 15–November 1.
M. Arid West—USDA Plant Hardiness Zones 5, 6, 7. Optimum planting time: September 30–November 30.
N. North Pacific Coast—USDA Zone 8. Optimum planting time: October 1–November 30.
O. South Pacific Coast—USDA Plant Hardiness Zones 9, 10. Optimum planting time: August 15–December 15 (baboon flower, flame freesia, freesia, bearded iris, corn lily, ornamental onion, squill, wandflower, wood sorrel); August 15–January 31 (bluebell, Persian buttercup (ranunculus), daffodil, grape hyacinth, Dutch iris, lily, windflower).
P. Alaska—USDA Plant Hardiness Zones 1–7. Optimum planting time: September 15–October 15.
Bulb Planting Regions map courtesy of Netherlands Flower Bulb Information Center.