Cedar of Lebanon Root Spread: Estimating the Root Protection Zone

Root Zone Formula

Root spread ≈ 1.5 × canopy radius. For a 30 m (100 ft) tall specimen with broad limbs:

• Canopy radius: ~10–15 m (30–50 ft).
• Root radius: ~15–22 m (50–75 ft).
• Most roots in top 60–90 cm (2–3 ft).

Soil Texture Modifies Spread

• Sandy soil → wider, deeper roots.
• Clay soil → shallower, more concentrated.

Practical Implications

• Construction within root zone requires arborist supervision.
• Root pruning: can cut small roots (<5 cm) at distance; avoid large structural roots near trunk.
• Mulch entire root zone if possible—greatest benefit for veteran trees.

Conservation Note

Cedar of Lebanon (Cedrus libani) is a heritage species. Root protection zone should extend to 1.5× drip line for maximum longevity.