Issaquah, WA Landscaping Rules: Native Plants (2026)
Key Facts
- Native trees required
- 50 percent of trees (§ 18.606.040(E)(2))
- Native shrubs and groundcovers
- 30 percent
- Cap on any one species
- No more than 50 percent
- Pollinator plants
- 10 percent of shrubs and groundcovers minimum
- Native soil retention
- 25 percent nonresidential and multifamily; 30 percent single-family
- Species lists
- King County's Native Plant Guide
Summary
In Issaquah, new landscaping covered by the Land Use Code must use native or drought-tolerant plants, or nonnative species adapted to the King County lowland climate. Site plantings must contain 50 percent native trees and 30 percent native shrubs and groundcovers, with no more than 50 percent of any one species.
1. New plant materials must consist of native or drought-tolerant varieties or nonnative species that have adapted to the climate conditions of the King County lowland environment. Appropriate locations and species must be selected to ensure plants will thrive, considering how the impacts of climate change can add undue stress to native plants in an urban environment. In some cases, native plants may need to be irrigated to survive. ... 2. There must be a diversity of tree and shrub genus and species in the site landscaping and must contain 50 percent native trees per IMC 18.812.080 , Replacement trees, and 30 percent native shrubs and groundcovers. No more than 50 percent may be of one species. ... 5. A minimum of 10 percent of shrubs and groundcovers must be known to attract regional pollinator species.
Full Breakdown
Issaquah Land Use Code § 18.606.040(E) sets the plant selection rule for every landscape area that Chapter 18.606 reaches. Paragraph (E)(1) requires new plant materials to be native or drought-tolerant varieties, or nonnative species that have adapted to the climate conditions of the King County lowland environment. The code sends applicants to King County's Native Plant Guide for the drought-tolerant and native species lists, and it concedes that native plants sometimes need irrigation to survive in an urban setting where climate change adds stress.
The mix is numeric. Paragraph (E)(2) requires diversity of tree and shrub genus and species, 50 percent native trees (tied to IMC 18.812.080, Replacement trees) and 30 percent native shrubs and groundcovers, and it caps any one species at 50 percent. Paragraph (E)(5) adds that a minimum of 10 percent of shrubs and groundcovers must be known to attract regional pollinator species. Paragraph (E)(3) tells designers to choose plants for mature size and available space, and gives large native conifers in densely built areas and narrow planter beds as its example of a poor fit. Paragraph (E)(6) requires tree species to come from the City preferred and prohibited tree list.
Existing native vegetation is protected separately. Under § 18.606.050(F)(3), a project with existing native vegetation areas must retain a minimum of the native soil area: 25 percent for nonresidential uses and multifamily, and 30 percent for single-family residential uses.
Scope matters. Section 18.606.020 applies the chapter to new development, subdivision of property, development or redevelopment in, adjacent to, or affecting critical areas, and any redevelopment or project that increases impervious surface area by 20 percent or more. Section 18.606.030 exempts single-family use lots with a detached single-family home, middle housing developments, accessory dwelling units, and small projects with five or fewer new trees or 1,000 square feet of landscaping from the permitting and bonding requirements of the chapter. Section 18.606.025(A) requires landscaping to conform when the cost of an addition, alteration, or repair exceeds 50 percent of the value of the existing building or structure.
Violations & Fines
Violations of Chapter 18.606 fall under the enforcement and penalty provisions of Chapters 18.108 and 18.812 IMC (§ 18.606.180(A)), and § 18.108.010 treats Land Use Code violations as civil violations penalized under Chapter 8.45 IMC. For Level 3 or 4 approvals, § 18.606.160 requires a performance guarantee of 150 percent of the total costs of the improvements. If approved plantings die within three years, the City sends a correction letter and, after 60 days without correction, uses the bond to replace them.
Frequently Asked Questions
Do I have to plant only native plants in Issaquah?
Does a single-family house need a landscape permit under this chapter?
Where do I find the list of acceptable native plants?
Sources & Official References
Other rules in Issaquah
Compare Issaquah to another location·View the Washington landscaping rules overview
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Native Plants in Nearby Cities
How other cities in King County handle native plants.