What Is the Spring Bulb Planting Schedule?

Tulips, often the harbinger of spring, are planted as bulbs.

Flower bulbs that bloom in spring are best planted in autumn, as are many perennial flowers. When to plant depends on your U.S. Department of Agriculture plant hardiness zone. Your zone also determines which spring blooming bulbs you may successfully grow.

When to Plant

Daffodils are another early spring bloomer.

Plant spring-blooming bulbs approximately four to six weeks before the first freeze. This allows time for a healthy root system to develop. Planting earlier may result in early growth that can be damaged by harsh winter conditions.

Chilling the Bulbs

Crocus peek through in late winter.

Many spring-blooming bulbs require a 12- to 16-week period of chilling, according to Clemson University Cooperative Extension. Gardeners who do not experience this through weather conditions, as in USDA zones 8 through 10, should chill the bulbs in a refrigerator, away from fruits. Prechilled bulbs are available, but the cost may be prohibitive.

Southern Zones

Narcissus are also known as daffodils.

Bulbs grown in southern zones should often be treated as annuals, to be replanted, as the period of chilling is required for regrowth the following spring. Some varieties bloom in multiple years.

References

• Clemson University Cooperative Extension: Spring-Flowering Bulbs
• "The Plant Propagator's Bible"; Miranda Smith; 2007

Resources

• Oregon State University Extension Service: Plant Next Year's Spring Flowering Bulbs Now