Bulb Planting Depth and Spacing Chart (With the Rule Behind It)

Almost every bulb question comes back to two numbers: how deep and how far apart. The good news is that one rule covers most of them.

The three-times rule

Plant a bulb three times as deep as the bulb is tall. A 2-inch tulip bulb goes 6 inches down (measured from the base of the bulb to the soil surface). A 3-inch daffodil goes about 8 inches down.

Measure from the base of the bulb, not the tip, and always plant with the pointed end up.

The chart

• Tulips: 6–8 in deep, 4–6 in apart
• Daffodils & narcissus: 6–8 in deep, 4–6 in apart
• Hyacinths: 6 in deep, 5–6 in apart
• Crocus: 3–4 in deep, 3 in apart
• Allium: 4–6 in deep, 6–8 in apart
• Amaryllis (outdoors, zone 8+): 8 in deep, 12 in apart
• Lilies: 6–8 in deep, 8–12 in apart
• Bearded iris (rhizome): top half above soil, 12–18 in apart
• Spider lily (Lycoris): neck at soil level, 6–8 in apart
• Dahlias (tubers): 4–6 in deep, 18–24 in apart

When to break the rule

Three situations justify planting shallower or deeper:

• Heavy clay: plant slightly shallower and add grit under the bulb, so water drains away instead of pooling.
• Sandy soil: plant slightly deeper; sandy soil dries and shifts more.
• Very cold zones: plant at the deeper end of the range for extra insulation.

Rhizomes — bearded iris, and the swollen stems of some perennials — are the true exceptions. They want to sit at or above the surface, not buried.

Spacing: why it matters

Bulbs planted too close compete for water and nutrients and produce smaller flowers within two seasons. The rule of thumb is two to three bulb-widths between bulbs.

If you want a dense display in the first year, plant in layers: large bulbs deep, small bulbs (crocus, muscari) in the same hole above them. They flower at different times and use different soil depths.

After planting

Water once to settle the soil. Then leave them — most bulbs need nothing more until spring growth starts. Label the area, because it is easy to forget where bulbs are once the soil is bare.

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