Fall Bulb Planting: Depth, Spacing, and Timing

By Sophia Martinez · October 11, 2026

The Depth Rule

Plant bulbs at 2.5 to 3 times their height. A 2-inch daffodil bulb goes 6 inches deep (measured from the bulb base). Shallow planting exposes bulbs to freeze-thaw cycles; deep planting delays emergence.

Spacing Guidelines

Large bulbs (tulips, daffodils, alliums): 4–6 inches apart
Medium bulbs (hyacinths, crocus): 3–4 inches apart
Small bulbs (snowdrops, scilla, muscari): 2–3 inches apart

Timing by Region

Plant when soil temperature at 6-inch depth drops below 55°F. In zone 3–4, this is typically late September to early October. Zone 5–6: October to early November. Zone 7–8: November to December, or pre-chill bulbs for 12 weeks before planting.

Soil Preparation

Bulbs rot in poorly drained soil. Amend heavy clay with coarse sand and compost. Add bone meal or bulb fertilizer to the planting hole per package directions. Water well after planting to settle soil.

Naturalizing Technique

For informal drifts, scatter bulbs by hand and plant where they land. This creates natural-looking colonies that multiply over years. Daffodils and crocus naturalize best; most tulips decline after 2–3 years and need replanting.