Flagstaff, AZ Tree Protection: Parkway Planting (2026)

Flagstaff's Engineering Design Standards, Title 18, Landscaping Standards for Rights-of-Way, govern how street trees go into the parkway strip between the curb and the sidewalk. Section 13-18-004-0005.1 requires that street trees avoid random changes in species along a right-of-way for any given development, so a block reads as a consistent planting rather than a mix of species, and sets the minimum spacing at 45 feet between trees, typically located midway between curb and walk. An existing specimen or mature street tree already growing in that location counts toward meeting the spacing requirement, so a developer does not have to remove a healthy tree just to hit an exact interval.

Placement also has to account for visibility: trees are sited so they do not block signage or storefronts and are offset from building entrances, following Standard Detail 18-04-050. In denser, urban settings the code layers on Section 13-18-004-0005.2's separate spacing schedule by tree size, tighter than the 45-foot standard: small trees at 10 to 15 feet, medium trees at 15 to 20 feet, and large trees at 20 to 25 feet, planted with structural soil and, where used, ADA-compliant tree grates of at least 24 square feet.

Root barriers at least 24 inches deep are required within four feet of buildings, roads, or walkways, and every newly planted tree must be staked per Section 13-18-004-0005.6. Trees must be chosen from the pre-approved list carried in the Zoning Code's Title 10 landscape plant list. The Intent section, 13-18-001-0001, credits street tree planting in the right-of-way as an integral, required part of every street improvement, not an optional amenity.