Tulip bulbs should be planted about 3 times their height deep. In practical terms, that generally means roughly 6 inches (15 cm) deep for average garden tulips, with variations based on bulb size and soil conditions. Here’s a quick guide you can follow.

Quick planting depth guide

• Standard tulips: 6 inches (15 cm) deep
• Very large bulbs: 7–8 inches (18–20 cm) deep
• Small/miniature bulbs: 4–5 inches (10–12 cm) deep

How to determine exact depth

• Measure the bulb height from top to base. Plant three times that measurement deep.
• If you have sandy or well-drained soil, a slightly deeper depth helps prevent drying and encourages steady growth.
• If your soil is heavy or clay-rich, avoid overly shallow planting that can lead to moisture issues; consider a deeper placement or improved drainage.

Spacing and setup

• Space bulbs about 3 inches (7.5 cm) apart for larger bulbs; 2–3 inches (5–7.5 cm) for smaller ones.
• Dig individual holes or a trench at the chosen depth, place bulbs root side down, and backfill gently.
• Water thoroughly after planting to settle the soil and start root development.
• Use a light mulch after planting to suppress weeds and protect the soil through winter, but avoid piling mulch directly over the crown.

If you share your bulb size, soil type, and climate, I can tailor the depth and spacing more precisely for your situation.