A1000_-_Vegetation

21.10.1 Introduction

The chapter shows plant and seed mixes appropriate for a given situations. Consideration shall be given for visibility, amount of sunlight, irrigation, aesthetics, ease of maintenance, and slope when considering which plant/seed mixes are appropriate for a project.

21.10.2 General Maintenance Notes

Irrigate plants for 2-3 years during the establishment period.

Emphasize evergreen vegetation to limit debris accumulating in stormwater facilities.

Cut back dead plant material in late fall.

Prune to improve visibility as necessary.

Do not plant trees where they will impact underground infrastructure or liners.

21.10.3 Seed Mixes

Tables 4-32 through 4-39 provide various recommended seed mixes.

Table 4 - 32: Seed Mix Reference Table shows which seed mixes are appropriate for various BMPs.

Table 4 - 32: Seed Mix Reference Table
BMP	Appropriate Seed Mix Reference
BMP C120 - Temporary and Permanent Seeding	Table 4 - 33: Standard Temporary Erosion Control Seed Mix Table 4 - 34: Native Temporary Erosion Control Seed Mix Table 4 - 35: Landscaping Seed Mix Table 4 - 36: Low Growing Turf Seed Mix Table 4 - 37: Native Meadow Seed Mix
BMP T1010 - Basic Biofiltration Swale	Table 4 - 38: Native Basic Biofiltration Swale Seed Mix
BMP T1020 - Wet Biofiltration Swale	Table 4 - 39: Native Wet Biofiltration Swale Mix
BMP T1030 - Continuous Inflow Biofiltration Swale	Table 4 - 39: Native Wet Biofiltration Swale Mix

Table 4 - 33: Standard Temporary Erosion Control Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Festuca rubra var. commutata	Chewings fescue	40
Lolium perenne	perennial rye	40
Agrostis capillaris	colonial bentgrass	10
Trifolium repens	white Dutch clover	10

Table 4 - 34: Native Temporary Erosion Control Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Bromus carinatus	California brome	25
Deschampsia caespitosa	tufted hairgrass	15
Festuca rubra rubra	native red fescue	20
Hordeum brachyantherum	meadow barley	40

Table 4 - 35: Landscaping Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Lolium perenne	perennial rye	70
Festuca rubra var. commutata	Chewings fescue	30

Table 4 - 36: Low Growing Turf Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Festuca arundinaceae	dwarf tall fescue	45
Lolium perenne var. barclay	dwarf perennial rye	30
Festuca rubra	red fescue	20
Agrostis capillaris	colonial bentgrass	5

Table 4 - 37: Native Meadow Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Bromus carinatus	California brome	30
Deschampsia caespitosa	tufted hairgrass	10
Elymus glaucus	blue wildrye	10
Festuca roemerii	Roemer's fescue	20
Perennials
Achillea millefolium	yarrow	5
Eriophyllum lanatum	Oregon sunshine	5
Eschscholzia californica	California poppy	3
Lupinus bicolor	bicolor lupine	6
Solidago canadensis	Canada goldenrod	3
Annuals
Clarkia amoena	farewell to spring	5
Gilia capitata	globe gilia	3

Table 4 - 38: Native Basic Biofiltration Swale Seed Mix
Scientific Name	Common Name	Percent by Weight
Grasses
Beckmannia syzigachne	American slough grass	5
Danthonia californica	California oat grass	5
Deschampsia caespitosa	tufted hairgrass	15
Elymus glaucus	blue wildrye	30
Glyceria occidentalis	western mannagrass	15
Hordeum brachyantherum	meadow barley	30

Table 4 - 39: Native Wet Biofiltration Swale Mix
Scientific Name	Common Name	Percent by Weight
Grasses, Sedges, Rushes
Beckmannia syzigachne	American slough grass	10
Carex obnupta	slough sedge	40
Carex stipata	beaked sedge	5
Eleocharis palustris	common spikerush	5
Glyceria occidentalis	western mannagrass	20
Juncus patens	spreading rush	15
Scirpus microcarpus	small-fruited bullrush	5

Tables 4-40 through 4-43 provide plants appropriate for stormwater facilities. Pick plants that appropriate for the individual project site.

Table 4 - 41: General Stormwater Facility List provides a list of recommended plants that are appropriate where there are no visibility concerns and where it is likely that plants will be regulary watered and maintained (where staff/residents work or reside).

Table 4 - 42: High-Visibility and Low-Maintenance Stormwater Facility Plant List provides a list of recommended plants that are appropriate where visibility is a concern (such as facilities in the right-of-way).

Table 4 - 43: Saturated Stormwater Facility List provides a list of recommended plants that are appropriate where plants will be inundated with stormwater on a regular basis.

Applicants are also encouraged to utilize the Low Impact Development Technical: Guidance for Puget Sound available at: https://www.psp.wa.gov/downloads/LID/20121221_LIDmanual_FINAL_secure.pdf and the Rain Garden Handbook for Western Washington available at https://fortress.wa.gov/ecy/publications/publications/1310027.pdf as additional references.

Table 4 - 40: Plant List BMP Reference Table shows which plants are appropriate for various BMPs.

Table 4 - 40: Plant List BMP Reference Table
BMP	Appropriate Plant List Reference
BMP L601 - Rain Gardens	Table 4 - 41: General Stormwater Facility List Table 4 - 42: High-Visibility and Low-Maintenance Stormwater Facility Plant List Table 4 - 43: Saturated Stormwater Facility List
BMP L630 - Bioretention	Table 4 - 41: General Stormwater Facility List Table 4 - 42: High-Visibility and Low-Maintenance Stormwater Facility Plant List Table 4 - 43: Saturated Stormwater Facility List
BMP T1110 - Wetponds - Basic and Large	Table 4 - 43: Saturated Stormwater Facility List
BMP T1130 - Stormwater Treatment Wetlands	Table 4 - 41: General Stormwater Facility List Table 4 - 43: Saturated Stormwater Facility List
BMP T1140a - Combined Detention and Wetponds	Table 4 - 41: General Stormwater Facility List Table 4 - 43: Saturated Stormwater Facility List
BMP T1140c - Combined Detention and Stormwater Treatment Wetland	Table 4 - 41: General Stormwater Facility List Table 4 - 43: Saturated Stormwater Facility List

Table 4 - 41: General Stormwater Facility List
Scientific Name	Common Name	Zone			Exposure			Evergreen PNW Native		Mature Height	O.C. Spacing	Notes
		1	2	3	shade	p/s	sun
Trees
Acer circinatum	vine maple			X	●	◗		N	Y	20’-25’	15’	multi stemmed tree, attractive fall foliage
Arbutus unedo 'compacta'	dwarf strawberry tree			X		◗	Ο	Y	N	6’-8’	10’	bright red-orange berries, adds winter interest
Frangula purshiana	cascara		X	X		◗	Ο	N	Y	15’-20’	15’	high wildlife value
Parrotia persica	Persian ironwood			X		◗	Ο	N	N	25’-30’	15’	multi-stemmed tree, attractive fall foliage
Xanthocyparis nootkatensis	weeping Alaska yellow cear			X		◗	Ο	Y	N	20’-30’	15’	slender evergreen adds winter interest
Shrubs
Cornus stolonifera 'kelseyii'	Kelsey redstem dogwood	X	X	X		◗	Ο	N	Y	2’-3’	3’	red stems add winter interest
Gaultheria shallon	salal		X	X		◗	Ο	Y	Y	2’-3’	3’	blue-purple berries, spreads well in shade
Lavandula angustifolia	English lavendar			X		◗	Ο	Y	N	2’-3’	3’	high pollinator value, aromatic
Mahonia aquifolium	tall Oregon-grape		X	X		◗	Ο	Y	Y	5’-7’	3’	durable, high wildlife value
Mahonia nervosa	low Oregon-grape		X	X	●	◗		Y	Y	1’-2’	2’	high wildlife value, performs well in shade
Mahonia repens	creeping Oregon-grape		X	X		◗	Ο	Y	Y	1’-2’	2’	high wildlife value, drought tolerant
Morella californica	Pacific wax myrtle	X	X	X		◗	Ο	Y	Y	10’-20’	10’	needs room to grow, prunes well
Physocarpus capitatus	Pacific ninebark	X	X	X		◗	Ο	N	Y	8’-10’	6’	may require pruning, exfoliating bark
Ribes sanguineum	red-flowering currant		X	X		◗	Ο	N	Y	6’-8’	3’	high wildlife value, pink-red spring flowers attract hummingbirds
Symphoricar-pos albus	snowberry		X	X	●	◗	Ο	N	Y	3’-5’	3’	white berries add winter interest
Spiraea japonica	Japanese meadow-sweet	X	X	X		◗	Ο	N	N	3’-4’	3’	pink flowers, compact varieties
Vaccinium ovatutm	evergreen huckleberry		X	X	●	◗	Ο	Y	Y	5’-8’	3’	high wildlife value, edible fruits, slow-growing
Grasses, Sedges, and Rushes
Carex obnupta	slough sedge	X	X		●	◗	Ο	Y	Y	2’-5’	2’	spreads well in moist to wet areas, pollution tolerant
Carex stipata	beaked sedge	X	X			◗	Ο	N	Y	2’-3’	3’	high wildlife value
Carex testacea	orange New Zealand sedge	X	X	X		◗	Ο	N	N	1’-2’	2’	orange-bronze color adds year round interest
Deschampsia caespitosa	tufted hairgrass	X	X	X		◗	Ο	N	Y	2’-3’	3’	clump-forming cool season grass
Juncus effusus	soft rush	X	X			◗	Ο	Y	Y	1’-4’	3’	spreads aggressively in moist areas
Juncus ensifolius	dagger-leaf rush	X	X				Ο	Y	Y	<1’	1’	flattened stems, high wildlife value
Juncus patens	spreading rush	X	X			◗	Ο	Y	Y	1’-2’	2’	blue-green foliage, spreads well in moist areas
Juncus tenuis	path rush	X	X			◗	Ο	Y	Y	1’-2’	2’	bright green foliage
Ground Covers, Perennials, and Ferns
Achillea millefolium	yarrow			X	●	◗	Ο	N	Y	1’-3’	3’	high pollinator value, aromatic foliage
Aquilegia formosa	columbine			X		◗	Ο	N	Y	1’-2’	2’	cut back at end of season
Arctostaphy-los uva-ursi	kinnikinnick		X	X			Ο	Y	Y	<1’	2’	low-growing evergreen, white-pink flowers
Camus quamash	camas		X	X		◗	Ο	N	Y	<1’	1’	blue flowers add spring interest, dies back after flowering
Ceanothus gloriosus	Pt. Reyes Ceanothus		X	X			Ο	Y	Y	<1’	3’	high pollinator value
Echinacea purpurea	purple coneflower		X	X		◗	Ο	N	N	2’-3’	2’	high pollinator value, cut back at end of season
Fragaria chiloensis	coast strawberry		X	X		◗	Ο	Y	Y	<1’	1’	glossy leaves, spreads quickly by runners
Heuchera spp.	coral bells		X	X	●	◗		N	N	<1’	1’	many varieties with colorful foliage, trim dead leaves and flowers
Iris douglasiana	Douglas iris	X	X	X		◗	Ο	N	Y	1’-2’	2’	cut back at end of season
Polystichum munitum	sword fern		X	X	●	◗		Y	Y	2’-3’	2’	large evergreen fronds add winter interest and structure
Rudbeckia fulgida	black-eyed susan		X	X		◗	Ο	N	N	1’-2’	2’	yellow flowers throughout sumer, cut back at end of season
Sedum 'autumn joy'	Autumn joy stonecrop			X			Ο	N	N	1’-2’	2’	pink flowers add fall interest, cut back at end of season
Sedum reflexum	reflexed stonecrop			X			Ο	Y	Y	<1’	1’	low-growing, spreads well in dry areas and between rocks
Solidago canadensis	Canada goldenrod		X	X		◗	Ο	N	Y	2’-3’	2’	yellow flowers add late summer interest, high pollinator value
Solidago canadensis	Douglas aster		X	X		◗	Ο	N	Y	2’-3’	2’	high pollinator value, cut back at end of season
Tolmeia menziesii	youth-on-age		X	X	●	◗		N	Y	<1’	1’	spreads well in moist areas, trim dead leaves and flowers

Table 4 - 42: High-Visibility and Low-Maintenance Stormwater Facility Plant List
Scientific Name	Common Name	Zone			Exposure			Evergreen PNW Native		Mature Height	O.C. Spacing	Notes
		1	2	3	shade	p/s	sun
Shrubs
Cornus sericea 'kelseyii'	Kelsey redstem dogwood	X	X	X		◗	Ο	N	Y	2’-3’	3’	compact form, red stems add winter interest
Gaultheria shallon	salal		X	X	●	◗		Y	Y	2’-3’	3’	blue-purple berries, spreads well in shade
Mahonia nervosa	low Oregon grape		X	X	●	◗		Y	Y	1’-2’	2’	high wildlife value, performs well in shade
Mahonia repens	creeping Oregon grape		X	X		◗	Ο	Y	Y	1’-2’	2’	high wildlife value, drought tolerant
Symphoricar-pos albus	snowberry		X	X	●	◗	Ο	N	Y	3’-5’	3’	white berries add winter interest
Grasses, Sedges, and Rushes
Carex obnupta	slough sedge	X	X		●	◗	Ο	Y	Y	2’-4’	3’	spreads well in moist to wet areas, pollution tolerant
Juncus effusus	soft rush	X	X			◗	Ο	Y	Y	1’-4’	3’	spreads aggressively in moist areas
Juncus ensifolius	dagger-leaf rush	X	X			◗	Ο	Y	Y	<1’	1’	flattened stems, high wildlife value
Juncus patens	spreading rush	X	X			◗	Ο	Y	Y	1’-2’	3’	blue-green foliage, spreads well in moist areas
Ground Covers, Perennials, and Ferns
Arctostaphy-los uva-ursi	kinnikinnick		X	X			Ο	Y	Y	<1’	2’	low-growing evergreen, white-pink flowers
Ceanothus gloriosus	Pt. Reyes Ceanothus		X	X		◗	Ο	Y	Y	<1’	3’	blue flowers add spring interest, dies back after flowering
Fragaria chiloensis	coast strawberry		X	X		◗	Ο	Y	Y	<1’	1’	glossy leaves, spreads quickly by runners
Polystichum munitum	sword fern		X	X	●	◗		Y	Y	2’-3’	2’	large evergreen fronds add winter interest and structure
Sedum reflexum	reflexed stonecrop			X			Ο	Y	Y	<1’	1’	low-growing, spreads well in dry areas and between rocks

Table 4 - 43: Saturated Stormwater Facility List
Scientific Name	Common Name	Zone			Exposure			Evergreen PNW Native		Mature Height	O.C. Spacing	Notes
		1	2	3	shade	p/s	sun
Grasses, Sedges, and Rushes
Carex obnupta	slough sedge	saturated			●	◗	Ο	Y	Y	2’-5’	2’	spreads well in moist to wet areas, pollution tolerant
Carex stipata	beaked sedge	saturated				◗	Ο	N	Y	2’-3’	3’	high wildlife value
Eleocharis palustris	creeping spikerush	saturated					Ο	N	Y	1-3’	2’	forms small clumps
Schoenoplectus acutus	hardstem bulrush	saturated					Ο	N	Y	3’-6’	2’	spreads well in wet areas
Scirpus microcarpus	panicled bulrush	saturated					Ο	Y	Y	2’-3’	1’	persistent spiky flowers, spreads well in moist to wet areas
Shrubs
Cornus stolonifera	redosier dogwood	saturated				◗	Ο	N	Y	7’-9’	6’	native form, spreads aggressively in moist to wet areas
Spiraea douglasii	Douglas spiraea	saturated				◗	Ο	N	Y	4’-7’	5’	spreads aggressively in moist to wet areas, pink flowers