Seattle Green Factor

What Is It?

Seattle Green Factor is a score-based code requirement that increases the amount of and improves the quality of landscaping in new development. Landscaping plays an important role in how new development looks and functions. Well-designed landscaping:

• Improves the look and feel of a neighborhood
• Reduces stormwater runoff
• Cools cities during heat waves
• Provides habitat for birds and beneficial insects
• Supports adjacent businesses
• Decreases crime

If your project is required to meet the Seattle Green Factor, you must reach a minimum score established by the zoning of your property. You can choose from a “menu” of landscape credits for various features, including green roofs, rain gardens, vegetated walls, and trees, and shrubs. You can receive bonus credits if you plant along the sidewalk, use native plants, or create a food garden.

For case studies of how the Seattle Green Factor can be applied to a project, see our Seattle Green Factor photo gallery.

Read the Code

The standards of Seattle Green Factor are established in Seattle Municipal Code (SMC) 23.86.019. Detailed requirements for affected zones are as follows:

• Neighborhood Residential (NR): Minimum score of 0.60 to allow greater FAR or density for stacked units and institutions(SMC 23.44.050.E, SMC 23.44.060.A, 23.44.070, 23.44.180)
• Lowrise Multifamily Residential (LR): Minimum score 0.60 (SMC 23.45.524)
• Midrise and Highrise Multifamily Residential (MR, HR): Minimum score 0.50 (SMC 23.45.524)
• Commercial and Neighborhood Commercial (NC1, NC2, NC3, C1, C2): Minimum score 0.30 (SMC 23.47A.016>) 
• Seattle Mixed (SM): Minimum score of 0.30 (SMC 23.48.055)  
• Development in South Downtown (variety of zones within the South Downtown planning area): Minimum score of 0.30 for development with 20,000 gross square feet or more (SMC 23.49.031)
• Urban Industrial, Industry and Innovation, and Industrial Commercial (UI, II and IC): Minimum score of 0.30 (SMC 23.50A.182 and 23.50A.184).
• Maritime, Manufacturing, and Logistics (MML): Solid Waste transfer stations minimum score of 0.40 (23.50A.186)
• Yesler Terrace (MPC-YT): Minimum score of 0.30 per development, 0.50 per sector (SMC 23.75.160)

Supporting Documents:

• Green Factor Scoresheet and Worksheet – a user-friendly version of the Seattle Green scoring system in SMC 23.86.019
• Rainwater Harvesting Calculation Tool
• Director's Rule 11-2020, Standards for Landscaping including Green Factor
• Sample Landscape Management Plan
• Green Factor Tree List (2008)
• Green Factor Plant List (2010)

Proposed Changes

For proposed changes to land use regulations, see our Changes to Code page and the Office of Planning and Community Development's Ongoing Initiatives list.