Wonder Walls Part II



Each time I return to the West Country I am reminded just how damp it is compared to Kent. A crude comparison of averages would tell you that twice as much rain falls in Devon or Cornwall versus Kent or East Anglia. On the surface, the impact of rainfall on landscape and nature is minimal: many of the same plants grow on either coast of the British Isles. However, many more, including ferns, mosses and perennial wildflowers, excel in the mild maritime counties of the West. I’m always staggered by the profusion of foxgloves, campions, lady ferns and cow parsley that explode from Cornish lanesides in spring; at the speed with which new Cornish hedges are cloaked with growth after construction; and the way every surface – hard or soft, dark or light – provides a refuge for some living thing or another. In the West Country, even exposed granite boulders and sheer cliffs shelter an extraordinary abundance of plants that have adapted to survive salt spray and extreme exposure. Their existence relies on one factor above all: the availability of water.


Pennywort (Umbilicus rupestris) in a Cornish hedge at Boscastle


Two years ago at Easter I wrote about Cornish hedges in a post entitled Wonder Walls. A typical Cornish hedge is a stone-faced earth bank with bushes or trees planted along the top. It is always referred to as a hedge, rather than a hedgerow or wall. Farmers have constructed these stone hedges over the ages to keep livestock in and intruders out. They are part of the very fabric of Cornwall and create a species-rich habitat of national importance.


Wild garlic (Allium ursinum), colonising the top and sides of a low Cornish hedge


The ecosystem of a Cornish hedge relies on maintaining moisture in an earth core. The hedge must be correctly built, founded on subsoil and with more subsoil or clay-shale at its core. Clay and stone are cooling and encourage moisture condensation. The laying of stones with a proper batter allows just the right amount of water to seep into the core. Dampness inside is conserved by green growth, which should never be removed by trimming in summer. The low fertility of the subsoil and the tightness of a hedge’s construction make it difficult for invasive weeds like nettles, elders and docks to encroach. The result is a complex, abundant and visually exciting ecosystem supporting hundreds of plants and thousands of insect species.


Common scurvy-grass (Cochlearia officinalis) and sea thrift (Armeria maritima) at Port Gaverne


Holidaying in North Cornwall I am once again hemmed in by walls and rocks literally dripping with plants and flowers. At Port Gaverne, just a 5 minute walk from our cottage, there are colossal boulders sheltering dwarf hummocks of sea thrift and common scurvy grass. In more exposed positions, common orange lichen, Xanthoria parietina, colonises stone surfaces where little else would survive. The lichen derives essential nutrients from bird droppings and water from dew and rain.


Common orange lichen on granite at Port Gaverne


Today at Boscastle, we took a route down Old Street to the harbour. Here in a valley, conditions on the vertical are very different to those found on the clifftops. Cornish garden walls are famed for their colourful cascades of aubretia, alyssum, Sicilian camomile (Anthemis punctata subsp. cupaniana), osteospermum, campanula, phlox, saxifrage ….. you name it, it grows.


Saxifrages and aubretias find a home on a sunny wall


And where walls are left shaded and uncultivated they are rapidly colonized by hart’s tongue and lady ferns, wild garlic, dog’s mercury, ivy and, in the image below, a foreign interloper, mind-your-own-business (Soleirolia soleirolii). Once you have this invasive little creeper in your garden you will never be without it – it’s like terrestrial duckweed – and chances are it will escape to any neighbouring spots that offer its preferred cool, damp, conditions. If mind-your-own-business has one saving grace, it is its ability to create an attractive green carpet in places where a lawn would be a disaster. Used well, between paving stones, as an edging to a fernery or as a houseplant in a shady bathroom, it can be very pretty indeed.


Wild garlic (Allium ursinum) and mind-your-own-business (Soleirolia soleirolii) cloaking a shady bank


Walls and Cornish hedges offer shelter from the elements and exposure to, or shade from the sun. Combined with a ready source of moisture from core of cool earth, spring, rain or mist they become unique, vibrant, colourful, multi-layered habitats that enhance our countryside and gardens in equal measure. Here in the West Country, where rain is plentiful and regular, they are one of the most attractive landscape features … unless, that is, you are trying to pass a car coming in the opposite direction.

For a moment of zen, here’s a very short video of spring water dripping down a moss-covered wall on the way to the harbour at Boscastle today.