The best time to plant spring-flowering bulbs is in the fall, about 6 to 8 weeks before the ground freezes. This timing allows the bulbs to establish roots before winter. The exact planting time depends on the climate zone:

• Zones 4-5: September to October
• Zones 6-7: October to early November
• Zones 8-9: November to early December
• Zone 10: Late December to early January (with pre-chilling in the fridge recommended for warmer zones)

Spring bulbs usually require cold weeks to flower well and should be planted when soil temperatures are cool, with nighttime temperatures between 40-50°F (about 4-10°C). Tulips can be planted slightly later than other bulbs, even into early winter. This general guidance applies broadly across climates to ensure bulbs get enough chilling to bloom beautifully in spring.