Snohomish City Zoning Code
CHAPTER 14
240 Landscaping Standards
14.240.010 Purpose and Intent.
Landscaping is a key component of Snohomish’s scenic character. The purpose of this chapter is to maintain and enhance property values; enhance compatibility between land uses and zones; screen undesirable views from adjoining streets and properties; provide a visual buffer and physical separation between land uses of varying intensities on abutting properties; minimize the impacts of noise, light, and glare; moderate the microclimate; provide privacy; reduce dust; reduce the visual appearance of paved parking lots; reduce stormwater runoff and pollution of surface waters; reduce erosion and sedimentation; promote utilization of natural systems; conserve energy; improve air quality; aid in regulating vehicle circulation; promote public safety; improve Snohomish’s quality of life; maintain and enhance canopy coverage; implement the policies of the Comprehensive Plan; and retain existing natural vegetation and protect and preserve urban wildlife habitat to the extent feasible. (Ord. 2516, 2025)
14.240.020 Applicability.
The Planning and Development Services Department (the “Department”) shall review and may approve, disapprove or approve with modification all site/landscape plans for all uses and developments which are required to provide landscaping in accordance with the requirements of individual zones and the provisions of this chapter. No permit for use that is subject to the requirements of this section shall be issued until the landscape plan for such use has been approved by the Department. This chapter shall apply under the following circumstances:
A. New Development. All new development shall provide landscaping in accordance with the requirements of this chapter when the provisions of SMC 14.240.050(A) Table 2 indicates a particular landscape type applies, or when additional specific landscaping requirements are imposed as part of a discretionary permit review process.
The following application classifications shall require landscaping review:
1. Site development plan.
2. Shoreline substantial development permit.
3. Preliminary plat/unit lot subdivision.
4. Preliminary planned residential development.
5. Development agreement.
B. Expansions of or Alterations to Existing Sites. The requirements of this section shall apply to remodeling or expansion of existing uses. Where conformance with this section would create a nonconformity of parking standards or would conflict with the location of existing buildings on the lot, the Planning Director shall determine how the code is to be applied. Where a nonconformity with parking standards will be created, the Planning Director may consult with the City Engineer. In determining how to apply the landscaping requirements in such circumstances, the Planning Director may allow landscaping to be clustered on portions of the site visible from adjacent streets and shall use the following criteria in deciding which of the landscaping requirements to adjust, listed in the order of highest importance:
1. Compliance with street frontage landscaping standards;
2. Compliance with perimeter landscaping standards;
3. Compliance with internal area of parking lot standards;
4. Compliance with other landscaping standards of this title. (Ord. 2516, 2025)
14.240.030 General Provisions.
A. Landscape Plan Submittal Requirements. The following materials must be submitted as part of applications for construction permits. The Planning Director shall have the authority to waive certain application materials if the item is not necessary to evaluate a specific proposal for consistency with this chapter. Plans shall be prepared by a licensed landscape architect, certified nurseryman or other trained person determined by the Planning Director as qualified to provide acceptable landscape plans. All plans shall be drawn to scale.
1. A site plan prepared by a qualified tree professional, drawn to scale and showing the following:
a. Location of all site improvements, including existing and proposed structures, construction limits, paving, utilities, and grading.
b. Location of all easements, critical areas and buffers, construction protection barriers, driplines, and critical root zones for trees to be retained.
c. Location, size and species of all significant trees to be retained and removed.
d. Location of all root barrier for plantings proposed within or adjacent to the right-of-way.
2. A planting plan showing the following:
a. Location of proposed structures and retained trees.
b. Location of proposed replacement trees and other vegetation, including size, species, and spacing.
c. Location and design of other landscape restoration measures.
d. Location and design of any open space and/or recreation features.
e. A planting schedule that indicates proposed species, quantity, size, spacing, and tree canopy calculations for planted trees.
f. Irrigation system, if proposed, including location and specifications.
3. An arborist report or professional recommendations may be required, assessing the health of existing significant trees to be retained, identifying hazardous trees, and recommending protection measures during construction activities.
B. Plant Selection. Plant species shall be either native or non-invasive naturalized species to the coastal region of the Pacific Northwest. Species shall be selected from the City of Snohomish Urban Forestry Species List or be suitable in the USDA Plant Hardiness Zone established for the area. Plants used for low impact development facilities shall be selected from the bioretention plant lists contained in Appendix 3 of the LID Technical Guidance Manual for Puget Sound and/or the Stormwater Manual as adopted per Chapter 15.16 SMC (SWMMWW) for stormwater facility plantings. At least 60 percent of new landscaping materials shall consist of drought-tolerant species, except where site conditions within the required landscape areas ensure adequate moisture for growth. Species shall be distributed and irrigated in a manner that uses water efficiently based on water demands. Selected plants must be suited to local soil conditions, if the site is not irrigated.
C. Exemptions. The following activities are exempt from the requirement to obtain plan approval:
1. Maintenance of required landscape areas.
2. Replacement of plants or plant material that is dead or damaged.
D. Alternative Landscaping Plans. The applicant may submit for consideration a landscaping plan that differs from the specific criteria set forth in this chapter, if the proposed landscaping complies with the stated purpose and intent of the chapter and, as determined by the Planning Director, is more effective than would result by following this chapter.
1. Alternative landscaping plans for perimeter landscaping requirements of SMC 14.240.050(B) shall consist of the following:
a. An alternative perimeter landscaping plan proposed by the applicant that exceeds the intent of the landscaping type and width required pursuant to Table 2.
b. A combination of a solid fence pursuant to Chapter 14.110 SMC constructed along the property line abutting adjacent uses to serve as a visual barrier, with landscaping and forestry consolidated in clustered areas.
i. Each landscape area proposed under this alternative shall be large enough to support at least one protected tree at its normal maturity in addition to other landscaping. Protected tree(s) shall be installed by the applicant.
ii. The applicant shall provide a calculation of the anticipated benefits at maturity compared to strict adherence of perimeter landscaping requirements of SMC 14.240.050, demonstrating improved performance in terms of shade, stormwater infiltration, tree density/DBH, and/or canopy coverage prepared by a qualified tree professional.
iii. The applicant shall supply the surveyed location and species prior to final acceptance of site improvements. All trees installed under this alternative landscaping plan shall be added to the City’s tree inventory.
iv. This option is not available as a substitute for the Type IV landscaping type.
2. Alternative landscaping plans shall be requested in writing by the applicant, including any supporting documentation, and shall be processed as an administrative determination of equivalence pursuant to SMC 14.20.020. (Ord. 2516, 2025)
14.240.040 General Landscaping Requirements.
Landscaping requirements for parking lot and site development are set forth in the adopted design standards that apply to the zone in which the proposed development is located. Landscape plant materials used in low impact development facilities may be considered for review by the Planning Director when evaluating compliance with the landscape and screening requirements.
A. Street Trees Required. The following land use actions shall require the installation of street trees:
1. Short plat;
2. Plat;
3. Unit lot subdivision;
4. Planned residential development;
5. Site development plan;
6. Shoreline substantial development permit;
7. Any activity involving street frontage improvements.
All trees and other landscape materials, planted adjacent to streets or in street right(s)-of-way including for the purpose of low impact development facilities, must have approval from the City prior to planting and conform to the ROW vegetation maintenance regulations.
B. Plant Sizing at Installation. All plants shall have the following minimum size at the time of planting:
1. Deciduous trees: minimum two and one-half inches. When multiple trees are installed at one time, the caliper of all trees may be averaged, but no individual tree shall have a caliper of less than one and three-quarters inches.
2. Evergreen trees: six- to eight-foot minimum height.
3. Medium and tall shrubs: minimum five-gallon size, at least 18 inches in height when mature height is three feet or more.
4. Ground cover: four-inch minimum pot size.
5. Grasses: one-gallon minimum pot size.
C. Minimum Spacing Requirements.
1. Deciduous trees: Variable based on location and density requirements. Refer to Table 1 and applicable design standards.
2. Evergreen trees: Variable based on location and density requirements. Refer to Table 1 and applicable design standards.
3. Medium and tall shrubs: Variable based on location and density requirements. Refer to Table 1 and applicable design standards.
4. Ground cover: Planted 18 inches on-center and cover within two years.
5. Grasses: Planted a maximum of three feet on-center, depending on specific growth habits, and cover within three years. (Ord. 2516, 2025)
14.240.050 Landscaping Types and Requirements.
A. Landscaping Types. The landscaping types are summarized in Table 1. The intent and minimum requirements for each type are described in subsections (A)(1) through (A)(4) of this section.
Table 1. Landscaping Types
Type | Purpose (Summary) | Planting Area | Tree Standards | Shrub/ Groundcover Standards | Density |
|---|---|---|---|---|---|
Type I | Visually soften large open parking areas | Min 5' wide | Deciduous: Max 35' OC in continuous planting bed; Max 75' OC in segmented planting areas | Max height 36" groundcover and grass | 75% coverage in 2 years |
Type II | Visual relief; add to the quality of a development | Min 5' wide | Deciduous/ evergreen: Average 30' OC | Deciduous and evergreen combined to create an effective screen | 75% coverage in 2 years |
Type III | Visual separation of incompatible uses from streets, arterials, and along property lines | N/A | Deciduous: No more than 80% of trees Max 35' OC | 3 – 5' height | 75% coverage in 2 years |
Type IV | Solid sight barrier to separate incompatible uses; provide noise buffering | N/A | Evergreen: Double row, 15' OC | Earthen berm minimum 2 1/2' with groundcover and grasses | 85% coverage in 2 years |
1. Type I: Open Area Landscaping.
a. Purpose/Intent. To visually soften large open parking areas.
b. Description. Type I landscaping shall consist of deciduous trees in a continuous planting bed or within segmented planting areas; with shrubs and ground cover or grass.
Planting areas shall have a minimum width of five feet.
2. Type II: Ornamental Landscaping.
a. Purpose/Intent. To provide visual relief and add to the overall quality of a development by softening the effect of the new building on the landscape.
b. Description. Type II landscaping shall consist of evergreen and deciduous trees planted in beds at least five feet in width, along with evergreen and deciduous shrubs and ground cover.
3. Type III: Visual Buffer Landscaping.
a. Purpose/Intent. To provide visual separation of incompatible uses from streets, arterials, and along property lines.
b. Description. Type III landscaping shall consist of evergreen or a mixture of coniferous and deciduous trees; however, deciduous trees shall comprise no more than 80 percent of the total.
Tall shrubs and ground covers shall provide an effective visual screen within two years. An earthen berm with lower shrubs may be used in place of more level terrain with three-to-five-foot shrubs.
4. Type IV: Solid Screening.
a. Purpose/Intent. To provide a solid sight barrier to totally separate incompatible uses and provide some noise attenuation/buffering.
b. Description. Type IV landscaping shall consist of a double row of evergreen trees, planted offset atop an earthen berm at least two and one-half feet in height, with dense ground cover.
A six-foot-tall sight-screening fence may be incorporated into the landscaping in place of the earthen berm.
B. Perimeter Landscaping Requirements. The buffering requirements of Table 2 are intended to provide visual separation between abutting properties. The requirements of Table 2, including the designated landscaping type and minimum width, shall apply on the interior property lines between land uses.
In reaching a conclusion as to the exact landscaping buffer requirement to be used for a specific development proposal, consideration shall be given to any existing landscaping that exists or may have been required on the adjacent property and how the landscaping buffer required of the subject development may complement the earlier planting to produce a more effective result.
Buffer requirements may be adjusted based on approval of an alternative landscaping plan pursuant to SMC 14.240.030(D).
Table 2. Perimeter Landscaping Requirements
Adjacent Land Use* | Proposed Development Type | ||||
|---|---|---|---|---|---|
Single-Family | Multifamily Residential | Commercial | Industry/ Business Park | Mobile Home Park | |
Single-Family Residence | None | Type III | Type III | Type IV | Type III |
Multifamily Residence | None | Type III | Type III | Type IV | Type III |
Mobile Home Park | None | Type III | Type III | Type IV | None |
General Commercial | None | Type III | None | Type III | Type III |
Industry/Business Park | None | Type IV | Type III | None | Type III |
*Adjacent land use is based on the existing use and not the zoning district.
C. Other Landscaping Requirements. Landscaping for other types of development, including screening elements, is as designated in Table 3 below.
Table 3. Other Landscaping Requirements
Type of Use/Location | Type of Minimum Landscaping | ||||
|---|---|---|---|---|---|
Minimum width | Type I | Type II | Type III | Type IV | |
Trash/recycle/utility service areas | 5 feet* | X | |||
Mechanical/electrical equipment | 5 feet | X | |||
Parking lot/structure perimeter landscaping | 5 feet | X | |||
Driveway entrances/exits at streets | Minimum necessary for sight distance per SMC 14.210.150 | X | |||
Fire access areas, around hydrants and utility boxes | Minimum necessary | X | |||
Parking lot islands | 5 feet | X | |||
Freestanding signs | 2 feet | X | |||
Outside storage | 5 feet | X | |||
*An architectural wall or enclosure may be proposed to reduce the landscaping width.
(Ord. 2516, 2025)
14.240.060 Tree Canopy Requirements.
Development proposals subject to SMC 14.240.040(A) shall be required to meet the minimum tree canopy coverage requirements of Table 4.
A. New plantings shall meet the size and spacing requirements of this chapter.
B. Measurable tree canopy shall include evergreen and deciduous trees measuring a minimum of six feet in height, excluding invasive species or noxious weeds, located within the gross site area.
C. Existing or planted tree canopy may include street trees, trees located within perimeter landscaping areas, site landscaping, trees located within native growth protection area (NGPA) easements or tracts, within critical areas and their buffers, and in open space tracts or easements.
Table 4. Tree Canopy Coverage Requirements
Development Type | Minimum Tree Canopy Coverage |
|---|---|
Short plat | 30% |
Plat | 25% |
Unit lot subdivision | 15% |
Planned residential development | 30% |
Site development plan | 20% |
Shoreline substantial development permit | 20% |
Other activity requiring frontage improvements: | |
1. Residential development | 1. 30% |
2. Commercial/mixed-use development | 2. 20% |
3. Industrial development | 3. 15% |
D. Tree canopy coverage shall be measured according to the method described in Table 5, factoring in any credits allowed pursuant to subsection F of this section.
E. Tree canopy coverage calculations shall be prepared by a qualified tree professional or a licensed land surveyor and submitted to the Department as part of the tree retention plan. The submittal shall include the existing canopy survey or aerial image with canopies and measurements shown, including the aerial imagery date, if applicable. Canopy coverage calculations shall be displayed in a clear table that includes the following information:
1. All proposed tree species;
2. All existing and proposed canopy sizes, percentages, and measurements;
3. All required calculations for existing canopy and/or planted canopy by proposed tree species;
4. Calculation of credits proposed to be used pursuant to subsection F of this section, including location on the site and authorizing provision of the SMC;
5. Tree canopy calculation with and without credits being applied; and
6. Name and/or firm of the person who prepared the canopy calculations.
Table 5. Tree Canopy Measurement Method
Existing canopy | Planted canopy | |
|---|---|---|
Option 1: | Option 2: | Calculation at maturity |
Measure the average canopy radius for each tree to be retained (radius = r) | Measure site boundaries using accurate and current aerial imagery | For each proposed tree species: |
F. The following credits may be applied toward tree canopy calculations:
1. Significant trees preserved pursuant to the protected tree program of SMC 14.120.040, including those utilizing the setback reduction incentives of SMC 14.120.080(F), may be counted at 125 percent of their actual canopy area.
2. New trees installed pursuant to SMC 14.240.030(D)(1)(b) and proposed to be protected trees may be counted at 110 percent of their projected canopy area at maturity.
3. Each tree located within a cluster or stand of five or more significant trees may be counted at 200 percent of its actual canopy area.
4. Retained trees located within 20 feet of an on-site bioswale or bioretention facility may be counted at 150 percent of their actual canopy area.
5. New green roofs may be counted toward tree canopy at a rate of 25 square feet of tree canopy area per 100 square feet of green roof surface. If trees are incorporated into the green roof, those trees may also be counted as an additional 100 percent of their actual calculated 20-year canopy area.
G. All trees proposed for retention and calculated as existing canopy shall be protected during development activities pursuant to SMC 14.120.110. (Ord. 2516, 2025)
14.240.070 Performance Assurance.
All landscape installation shall be completed prior to final inspection of the applicable permit; however, if installation is incomplete at the time of formal application for occupancy because of weather-related reasons, the City will require that the applicant submit a bond or some other form of financial guarantee acceptable to the City equal to 150 percent of the estimated total cost of landscaping, including labor and materials. If the required landscaping is not made within six months of the occupancy of the building, the City will use the surety to install the landscaping. Prior to release of the performance bond, a maintenance guarantee shall be in effect pursuant to SMC 14.240.080. (Ord. 2516, 2025)
14.240.080 Maintenance Guarantee.
Vegetation must be maintained and kept healthy. A maintenance guarantee specified by the City as acceptable shall be provided by the developer/owner for any required landscaping, in an amount equal to 20 percent of the total landscape construction costs and shall be in effect for no less than three years. The developer/owner must provide this landscape maintenance guarantee to the City at the time of final inspection of the development project or other landscaping installation. (Ord. 2516, 2025)