The best time to plant tulip bulbs is in the autumn, typically from September to mid-November, or specifically October to November. This timing ensures the soil temperature drops below 10°C (around 50°F), which is important for the bulbs to start their cold period and develop properly. Planting in autumn also allows the bulbs to remain dormant over winter, which helps protect them from rotting and pests. The soil should not be too dry or too wet, and there should be no expected night frosts during planting. If you miss the autumn planting window, you can still plant tulip bulbs in early spring from mid-May, but they should be pre-germinated for best results. Some sources also say planting as late as December or even January can work, especially in mild climates, but the blooms might be smaller or less abundant. For warmer climates where the soil doesn't naturally get cold enough, tulips need at least 12-14 weeks of a cold period below 55°F (13°C), which can be simulated by chilling the bulbs in a refrigerator before planting. In summary:

• Ideal planting time: mid-September to mid-November (or October-November)
• Soil temperature below 10°C
• Avoid planting with expected night frosts or very wet/dry soil
• Can plant late (December, January) with some risk to bloom size
• Spring planting possible if bulbs are pre-germinated

This is the generally recommended planting time for tulips to bloom beautifully in spring.