19.65.050 Plant material and installation standards.
A. Native and Naturalized Plant Species. New landscaping materials must include species native to the region or hardy, waterwise, and noninvasive species appropriate in the climatic conditions of the region (decorative annuals are an exception). Generally acceptable plant materials must be those identified as hardy in Zone 8b as described in the United States Department of Agriculture’s Plant Hardiness Zone Map. The selection of plant species should include consideration of soil type and depth, the amount of maintenance required, spacing, exposure to sun and wind, the slope and contours of the site, compatibility with existing native vegetation preserved on the site, water conservation where needed, soil infiltration capacity, and the impact of landscaping on visibility of the site for purposes of public safety and surveillance.
B. Tree Standards and Guidelines.
1. Tree heights may be called for within this chapter or elsewhere within this title:
a. Large tree: capable of growing 35 feet high or greater under normal growing conditions.
b. Medium tree: capable of growing over 15 feet high and less than 35 feet high under normal growing conditions.
c. Small tree: capable of growing up to 15 feet high under normal growing conditions.
2. Unless otherwise noted herein, required trees must meet the following standards at the time of planting:
a. Required deciduous trees (other than street trees) must be fully branched, have a minimum caliper of one and one-half inches (as measured six inches above the root ball), and a minimum height of six feet at the time of planting.
b. Required deciduous trees within parking areas must be a minimum caliper of one inch (as measured six inches above the root ball) and a minimum height of 10 feet at the time of planting.
c. Required evergreen trees must be fully branched and a minimum of six feet in height, measured from the treetop to the ground, at the time of planting.
C. Shrub Standard. Shrubs, except for ornamental grasses, must be a minimum of one-gallon size at the time of planting.
D. Groundcover Standards and Guidelines.
1. Groundcovers must be planted and spaced to result in total coverage of the required landscape area within three years, or as per recommendations by a Washington State licensed landscape architect or Washington certified professional horticulturalist as follows:
a. Four-inch pots at 18 inches on center.
b. One-gallon or greater sized containers at 24 inches on center.
c. A bed of flowers in place of groundcover plants. A reduction in the minimum size may be permitted if certified by a Washington State licensed landscape architect or Washington certified professional horticulturalist that the reduction must not diminish the intended effect or the likelihood the plants will survive.
2. Grass is acceptable as groundcover in landscaped areas, but generally not preferred for water conservation and maintenance purposes (lawn areas designed as play areas are an exception).
3. Groundcover areas must contain at least two inches of composted organic material at finished grade.
E. Tree and Plant Diversity.
1. If there are more than eight required trees, no more than 40 percent of them may be of one species.
2. If there are more than 24 required trees, no more than 20 percent of them may be of one species.
3. If there are more than 24 required shrubs, no more than 75 percent of them may be of one species.
F. Soil Augmentation and Mulching.
1. Existing soils must be augmented with a two-inch layer of fully composted organic material tilled a minimum of six inches deep prior to initial planting.
2. Landscape areas must be covered with at least two inches of mulch to minimize evaporation. Mulch must consist of organic materials such as bark chips and wood grindings or yard waste, sawdust, and/or manure that is fully composted. Washed rock can also be used as a mulch.
G. Landscape Installation Standards.
1. All required landscaping must be in-ground, except when in raised planters. Plant materials will be installed to current nursery industry standards.
2. Plant materials must be properly supported to ensure survival. Support devices such as guy wires or stakes must not interfere with vehicular or pedestrian movement. Where support is necessary, stakes, guy wires or other measures must be removed as soon as the plant can support itself.
3. Existing trees and plant materials to be retained must be protected during construction, such as by use of chain-link or other sturdy fence placed at the dripline of trees to be retained. Grading, topsoil storage, construction material storage, vehicles and equipment must not be allowed within the dripline of trees to be retained.
4. Installation of landscaping materials must take into consideration access to utility vaults, pedestals, and other public and private utility facilities.
5. Tree/Shrub Height and Location. The landscape plan should plan for the mature size of trees and major shrubs to avoid interference with windows, decks or lighting.
6. Trees must be protected by fencing until they are mature enough to withstand typical wildlife activity. (Ord. 3040 § 2 (Att. A), 2019)