Rethinking Shoreline Gardens

Kathleen Sayce

Summer can be a thoughtful time for gardeners. First, we see the results of planning and planting in prior years as the plants grow and flower. Second, we naturally tend to think about what might have been—if only I’d planted five of those lilies instead of three; if only the deer hadn’t eaten down that rose; if only the croquet game on the 4th of July had not seen five children tromping (and bashing) through the rhododendrons to get their balls back to the playing field; if only . . .  Third, we contemplate what truly different kinds of gardens might be like. Autumn is a good time to revise and replant gardens, which intensifies thoughtful planning during the summer. 

Yellow sand verbena, Abronia latifolia, lives in open blowing sand areas on the beaches, and has showy bright yellow flowers. Not for a garden with improved soils, sand verbena is happiest in open sand. 

There are several ways to think about revising coastal gardens to reduce time, materials and energy spent caring for them, while still enjoying shrubs, perennials, grasses and other plants: 

One is to plant species that are truly salt, wind and rain tolerant, using those plants that thrive right along the ocean. 

Beach fleabane, Erigeron glaucus, is a low-growing daisy with pink to lavender flowers.Beach fleabane, Erigeron glaucus, is a low-growing daisy with pink to lavender flowers.

Two is to revise gardens to make them ocean friendly. A program of Surfrider Foundation, ( http://www.surfrider.org/programs/entry/ocean-friendly-gardens) ocean friendly gardening is being actively promoted in California. Prolonged drought in that state is driving a serious rethink of the lawn plus shrubs and perennials approach, also called ‘mow, chop and blow’.

Three is to rethink water needs, and shift to native plants that do not need summer water and live only with rainfall; this is called xeriscaping in drier climates. 

These approaches share a focus on water retention, soil building, use of compost and mulches, use of native and drought tolerant plants, and reducing hard surfaces to improve permeability. 

Beach lupine, Lupinus litoralis, lives in open sandy areas along the beach, and like sand verbena really prefers very sandy soils. 

The South Coast of Washington is not California, so the plants we can grow are a bit different, and we aren’t yet in drought conditions. However, unless you truly like dragging a hose around, I recommend re-planning your garden to reduce watering. I limit my watering to those plants by bird baths, and a few plants that grow in pots. The rest have to endure local conditions, or leave (read:  die). It sounds ruthless, but if you pay attention to what lives and what dies without summer water, then you can take a very important step––selecting plants that do not need summer watering. 

Yarrow, Achillea millefolium, grows in large patches, in the dunes, saltmarshes and seacliffs. Closely related species are pink, red, yellow and other colors, and all grow well on shorelines. 

Next comes evaluating just how close you are to the ocean. Within about one thousand feet of the beach, salt and wind are critical preconditions that define what you can successfully grow, and how to grow it. Many plants do well with regular watering in this zone, as watering washes salt off the plants and flushes salt from the soil. Watering all summer runs counter to low input gardening and no-to-low summer watering. It’s important instead to find those plants that tolerate salt and wind and drought, and put down the hose. 

For wetter sites, gumweed, Grindelia integrifolia, has buttery yellow daisy flowers in late summer. 

Plants that do well right along the coast include salal, kinnikinnick, sword fern, Pacific reedgrass, red fescue, tall hairgrass, snowberry, coastal mugwort, yarrow, dune tansy, dune goldenrod, Douglas aster, sea watch (a native angelica), edible thistle, pearly everlasting, nodding onion, beach fleabane, and strawberries. These plants naturally grow on the sea cliffs and in the dunes. There are also many xeric plants from other parts of the world that grow in dry summer shoreline conditions.  Xeric plants include lavender, rosemary, many grasses, some sedges, bulbs, and many more. The full list is long, too many to list or discuss here. For more information, see my blog at http://columbiacoast.blogspot.com, where I posted lists of native and introduced plants that do well along our shorelines.

One of the toughest native shrubs, salal, Gautheria shallon, grows on seacliffs and in dunes, with pink flowers and dark blue berries, and lovely evergreen foliage. 

The soil enhancement process is important to success for many plants. Adding carbon to the soil helps plants thrive in harsh conditions; these include compost, biochar and mulch.  Other shoreline gardening concepts include:  Permeable instead of impermeable surfaces (water absorbing rather than water resisting surfaces, which allow more water to enter the soil); choices for permeability include using gravel instead of concrete; paving with wide gaps, with gravel below, rather than all hard surfaces; mulches instead of bare soil; rain gardens and swales to help runoff water collect and soak into the ground and promote groundwater recharge. These all help retain water on site, clean it before it enters the ground water, and the ocean. 

Black twinberry, Lonicera involucrata, is a tough deciduous shrub with yellow flowers and brid-friendly black berries. 

The thinking behind ocean friendly gardening, at the Surfrider Foundation, is that present (and rapidly changing) ocean conditions are made worse by runoff water, often laden with heavy metals, chemicals from cars, nutrients and pesticides. Ocean-friendly-gardening also includes decoupling gutters from storm water collection systems so that water can recharge in the soil, and cleaning it biologically (with plants) before it reaches the groundwater or flows to nearby streams. 

Seawatch, Angelica lucida, lives on seacliffs, in dunes and salt marshes; four to six feet tall when flowering, plants are host to Anise Swallowtail butterfly larvae. 

These approaches help create gardens that need less water, no pesticides, less fertilizer, and less work to maintain. These aren’t flower-free gardens; they are full of flowers, are bee, butterfly and bird friendly, and are drought and fire resistant. 

As you watch your roses and lilies and geraniums bloom this year, what are you thinking about for next year? I’m rethinking the lawn along the salt marsh, wondering what a tall meadow would be like. I’d like to get rid of the lawn, but I don’t want my yard to go back to trees, which is its default plant community. This is a rainforest area, after all.  A tall meadow is mown once a year in late winter. Visualize tall grasses waving in the wind, punctuated by white angelica and pink native thistles, and magenta-pink spikes of checker mallow, and masses of yarrow. No watering. No summer mowing. I just have to take out those old lilac shrubs, and layer on compost to prep the soil; it could be ready to plant once the fall rains start, if I start this week. 

This and past columns are posted at http://columbiacoast.blogspot.com.

Native Shoreline Plants for Shoreline Gardens, South Coast, Washington

 Kathleen Sayce

Trees:

Red Alder, Alnus rubra, note that both alders need fairly damp conditions to thrive
Sitka Alder, Alnus sinuata
Sitka spruce, Picea sitchenisis
Shore pine, Pinus contorta var. contorta
Hooker’s willow, Salix hookeriana, note that all willows need fairly damp conditions to thrive
Pacific willow, Salix lucida ssp. lasiandra
Scouler’s willow, Salix scouleriana

Evergreen Shrubs: Severe winter storms will kill back portions of these shrubs. Prune and keep them growing, and they will survive these setbacks. 
Kinnikinnick, Arctostaphylos uva-ursi
Coyote-brush, Baccharis pilularis
Salal, Gaultheria shallon
Common juniper, Juniperus communis
Puget Sound Juniper, Juniperus maritima
Pacific wax myrtle, Myrica californica
Evergreen huckleberry, Vaccinium ovatum

Deciduous Shrubs:  Severe winter storms will kill back portions of these shrubs. Prune and keep them growing, and they will survive these setbacks. 
Ocean spray, Holodiscus discolor
Black twinberry, Lonicera involucrata
Snowberry, Symphoricarpos albus
Pacific crabapple, Malus fusca
Ninebark, Physocarpus capitatus
Nootka rose, Rosa nutkensis
Rose spirea, Spiraea douglasii 
Low blueberry, Vaccinium caespitosum

Perennials for low meadows and beds, under 36 inches tall:

Yarrow, Achillea millefolium
Nodding onion, Allium cernuum
Pearly everlasting, Anaphalis margaritacea
Coast silverweed, Argentina pacifica
Sea pink, Armeria maritima
Harvest brodiaea, Brodiaea coronaria
Common camas, Camassia quamash
Beach fleabane, Erigeron glaucus
California poppy, Eschscholzia californica
Coast strawberry, Fragaria chiloense
Chocolate lily, Fritillaria affinis
Beach gum weed, Grindelia integrifolia
Purple beachpea, Lathyrus japonicus
Gray beachpea, Lathyrus litoralis
Seashore lupine, Lupinus littoralis
Pacific lily of the valley, Maianthemum dilatatum
Coast piperia, Piperia elegans (P. greenii, P. maritima, Habenaria etc)
Western buttercup, Ranunculus occidentals
Oregon stonecrop, Sedum oreganum
Broad-leaved stonecrop, Sedum spathulatum
Dune goldenrod, Solidago spathulata
Hooded Ladies-tresses, Spiranthes romanzoffiana
Dune tansy, Tanacetum douglasii
White brodiaea, Triteleia hyacinthina
Early blue violet, Viola adunca

Perennials for tall meadows and beds, more than 36 inches tall:

Seawatch, Angelica lucida
Henderson’s angelica, Angelica hendersonii
Coastal mugwort, Artemisia suksdorfii
Edible thistle, Cirsium edule
Fireweed, Epilobium angustifolium
Western goldentop/goldenrod, Euthamia occidentalis (formerly Solidago)
Cow parsnip, Heracleum maximum
Arctic sweet coltsfoot, Petasites frigidus [likes wetter, shady sites]
Sword fern, Polystichum munitum
Henderson’s checkermallow, Sidalcea hendersonii

Grasses, Sedges & Rushes:

  Lower growing; foliage under 18 inches tall:
Short-stemmed sedge, Carex brevicaulis
Big-headed sedge, Carex macrocephala
Sand-dune sedge, Carex pansa
California oatgrass, Danthonia californica
Tufted hairgrass, Deschampsia cespitosa [flower spikes can be 5 ft tall]
Red fescue, Festuca rubra
Roemer’s fescue, Festuca roemerii
Idaho fescue, Festuca idahoensis
Baltic rush, Juncus arcticus ssp. littoralis
Dagger-leaf rush, Juncus ensifolius
Chilean rush, Juncus falcatus ssp. chilensis
Salt rush, Juncus lesueurii

  Taller; foliage over 18 inches tall

California brome, Bromus carinatus
Pacific brome, Bromus sitchensis
American dune grass, Leymus mollis
Pacific reedgrass, Calamagrostis nutkensis, for upland to wetland areas
Slough sedge, Carex obnupta, for freshwater wet areas
Lyngbye’s sedge, Carex lyngbyei, for saltwater wet areas
Reed manna grass, Glyceria grandis, for wetter soils
Marsh muhly, Muhlenbergia glomerata, for wetter soils

Introduced Plants for Shoreline Gardens, South Coast, Washington

Kathleen Sayce

See http://www.smgrowers.com/resources/seaside.pdf for more plants

Trees

Common alder, Alnus glutinous
Monterey cypress, Cupressus macrocarpa
Pines, including:
European black pine, Pinus nigra
French maritime pine, Pinus maritimus
Mugo pine, Pinus mughensis 
Holm oak, Quercus ilex

Shrubs:

Bottlebrush, Callistemon citrinus
Calluna species and varieties
Ceanothus, several
Cotoneaster, several 
Eleagnus x ebbingei
Erica species and varieties
Escallonia rubra
Japanese spindle, Euonymus japonicus
Hebe species and varieties
Sea buckthorne, Hippophae rhamnoides
Ilex species, smaller leaved forms do better with high salt winds
Juniperus, several species and varieties, look for lower growing forms
Rosa rugosa
Rosemary, Rosmarinus officinalis

Perennials

Lady’s mantle, Alchemilla mollis
Allium species, several
Greater sea kale, Crambe cordifolia
Sea kale, Crambe marítima
Montbretia, Crocosmia species and varieties
Ice plant, Delosperma species
Sea holly, Eryngium species and varieties
Geranium, some species and varieties (These are not pelargoniums)
Kniphofia species
Douglas iris, Iris douglaisana
Lavenders, Lavandula 
Catmint, Nepeta species and varieties
Bog sage, Salvia uliginosa
Santolina species
Sedum species, several 
Sempervivum species, several
Stachys byzantina
Thyme, Thymus
Verbena bonariensis
Vinca major

Low grasses, sedges, rushes: 

Sweet vernal grass, Anthoxanthum odoratum
Carex species
Heathgrass, Danthonia decumbens
Blue oat grass, Heliotrichon sempervirens
Seaside feather grass, Nasella tenuissima

Tall grasses and grass-like plants:

Calamagrostis, cultivated species and varieties
Cape rush, Chondropetalum tectorum
Pampas grass, Cortaderia selloana
Maiden grass, Miscanthus sinensis, and other varieties in this genus
Purple fountain grass, Pennisetum setaceum rubrum

New Zealand Flax, Phormium tenax, and several varieties