9 county-level rules, plus city-specific rules for 4 cities in Snohomish County, Washington.
Verified from official government sources
Snohomish County sets no maximum lawn or grass height for private residential yards in unincorporated areas. The old Title 7 nuisance chapters are repealed, and Title 10 covers only chronic (crime-related) nuisance property, not overgrown lawns. Height rules come from your city or HOA.
For new development, retained trees must be fenced at the drip line and not disturbed. Abutting owners may trim weeds, grass, brush and blackberries in the first 10 feet of an unopened right-of-way, but may not cut significant trees there.
SCC 13.10.050(7)
Trimming, pruning, or removal, by an abutting property owner, of weeds, grass, brush, blackberries and other similar vegetation located on the first 10 feet of an unopened deeded right-of-way abutting the property at issue; provided, that: Significant trees...are not removed.
Retained or replacement significant trees on Snohomish County development sites cannot be removed unless a certified arborist certifies a hazard in writing. Any retained significant tree damaged or removed during development must be replaced three-for-one, plus a fine.
SCC 30.25.016(12)
Any significant trees identified in a landscape plan to be retained and subsequently damaged or removed during site development shall be replaced at a rate of three trees for each one damaged or removed significant tree. Failure to replace...shall be subject to a fine as determined under chapter 30.85 SCC.
Snohomish County enforces state noxious-weed law. Every property owner must eradicate all Class A weeds and control designated Class B and listed Class C weeds. The county Noxious Weed Control Board (SCC Ch. 3.42) can order control and bill or lien the owner.
RCW 17.10.140(1)
Except as is provided under subsection (2) of this section, every owner must perform or cause to be performed those acts as may be necessary to: (a) Eradicate all class A noxious weeds; (b) Control and prevent the spread of all class B noxious weeds designated for control in that region within and from the owner's property.
Snohomish County government sets no countywide lawn-watering schedule. Outdoor water use is governed by your local water/utility purveyor (for example the Alderwood, Cross Valley, or PUD-served districts and cities), which may impose voluntary or mandatory restrictions during drought.
Rooftop rainwater collection for outdoor use is allowed in Snohomish County with no water-right permit, following Washington's 2009 state policy. Storage tanks and any plumbed indoor use still follow building/plumbing code, but landscape irrigation from a rain barrel needs no special county approval.
Snohomish County does not require native landscaping for homeowners, but Title 30 rewards it: development landscape plans that use Puget Sound indigenous species can lower the required evergreen share, and buffer enhancement with Pacific Northwest natives helps meet tree-canopy standards.
SCC 30.25.016(6)(a)(i)
The evergreen portion of the required planting mix may be reduced to 37.5 percent when the deciduous mix contains exclusively indigenous species to the Puget Sound region, not including Alder.
Snohomish County has no ordinance prohibiting or specifically permitting artificial turf in residential yards. In required development landscaping, the code directs that non-vegetative materials be minimized, but there is no turf rule for ordinary homeowners.
SCC 30.25.015(3)
Use of bark, mulch, gravel, and similar non-vegetative material shall be minimized and used only to assist plant growth and maintenance or to visually complement plant material.
Snohomish County has no ordinance banning backyard composting, and it is encouraged for yard waste. In the unincorporated county, residential solid-waste and recyclables collection is regulated under SCC Ch. 7.42, and yard/organics service is available through the county's contracted haulers.
4 cities in Snohomish County have their own landscaping rules rules. Each link goes to that city's dedicated page with code citations.
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