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.