Tulip bulbs are best planted a depth that’s roughly three times their height, with common guidelines around 5 to 7 inches (12.5 to 18 cm) deep for typical tulip varieties. Planting deeper helps protect the bulbs from temperature fluctuations and vermin, while shallower planting tends to produce weaker blooms or poorer longevity. Key guidelines

• General rule: Plant at about three times the bulb height.
• Typical depth range: Approximately 5–7 inches (12.5–18 cm) for standard-sized tulip bulbs.
• Soil and location considerations:
  • In sandy soils, plant a bit deeper to reduce moisture loss.
  • In heavier soils, ensure drainage is good; amend if needed.
  • Plant with the pointed end up and the flat base down.
• Spacing: Space bulbs roughly 4–6 inches apart to allow for growth and airflow.
• Mulch: A light mulch can help regulate soil temperature, but avoid piling mulch directly against tulip foliage.
• Climate adjustments:
  • In very cold regions, deeper planting (closer to 7 inches) can help.
  • In milder climates, 4–5 inches can sometimes be sufficient, but deeper planting often yields better perennial performance.

If you have a specific bulb size or variety, I can tailor the depth more precisely. Also, if you’re planting in containers, the depth and spacing are similar, but ensure the pot has good drainage and use a light, well-draining mix.