||Coastal plant style
We have examined the reasons why people want to live by the coast and also how they can create a garden to suit their lifestyle. We have also examined some of the challenges of gardening by the sea. But what about the plants? Which ones can grow where?
How to use hardiness zone maps
Before investing time, effort and, of course, money on new plant purchases, you should first understand your geographical location and what this means to the plants in your care. It is particularly important to have an appreciation of temperatures and the tolerance of plants to cold.
For many years the standard used in the United States has been the Harvard University-derived ‘hardiness zones’. The original zone map was that of the United States, but it has been adapted for use in the UK and Europe. These maps enable gardeners to judge how plants will grow and thrive, wherever they live.
Certain plants – such as the tropical cannas and bananas from the West Indies or Mediterranean regions, or the cacti and succulents of Mexico and South America – are obvious plant choices if you live in these zones. But if you live in England, or anywhere else in Europe or North America, these maps are designed to help you to understand
which plants will survive in your garden, with or without being cosseted.
Areas within the maps are colour-coded into
11 distinct zones. Plants mentioned in this part of the book will be given a zone reference from Z1 to Z11. Find your location on the maps, and you can then identify which zone your garden falls into. Do not forget to take into account that cities are warmer than rural locations, and that planting shelter belts of trees, or windbreaks, can dramatically improve conditions for plants.
Zone 1 below –50°F (–46°C)
Zone 2 –50° to –40°F (–46° to –40°C)
Zone 3 –40° to –30°F (–40° to –34.5°C)
Zone 4 –30° to –20°F (–34° to –29°C)
Zone 5 –20° to –10°F (–29° to –23°C)
Zone 6 –10° to 0°F (–23° to –18°C)
Zone 7 0° to 10°F (–18° to –12°C)
Zone 8 10° to 20°F (–12° to –7°C)
Zone 9 20° to 30°F (–7° to –1°C)
Zone 10 30° to 40°F (–1° to 4°C)
Zone 11 above 40°F (above 4°C)
Award of Garden Merit
Throughout the directory section that follows, you will see the initials ‘AGM’ set after certain plants. This denotes that the plant in question has passed certain assessments carried out by experts under the auspices of the Royal Horticultural Society in the UK. Only plants with exceptionally good garden qualities can be given this special Award of Garden Merit, which gives you a degree of reassurance.
All you have to do is choose a plant that is right for the situation and care for it properly.
The rule we have adopted for this chapter is that the plants included within it should be able to fend for themselves – that is, once they are properly planted and established in their positions. Think of wild plants growing on a clifftop or on exposed moorland – these are some of the toughest plants Nature has come up with!
What are tough plants?
Tough places to grow plants need tough plants to grow in them. This might sound blindingly obvious, but people often plant a delicate little thing in quite inhospitable conditions and are then surprised when it curls up its toes and dies.
Just what do we mean by ‘tough’? Well, we are referring to any plant that, once planted in the right environment, can be expected to flourish with the minimum of cosseting and effort. Such a plant will be flexible, tenacious and able to endure hardship. Some plants are naturally hardier souls – what you might consider as the plant world equivalent of the ‘street ruffian’, able and willing to fight back.
However, not all of the plants featured in this chapter are tough in every respect. There may be some that endure gale-force winds with ease, but dislike intense cold. Others may be fine with a constant coastal battering, but they will not appreciate a wet soil.
A coastal garden, especially if it is also at altitude (such as on top of a cliff or hillside), can be one of the most inhospitable places for plants. When wind is combined with other conditions such as hail, extreme cold and, of course, salty air, its effect will be exacerbated.
Moorland areas, being of high altitude, will also be incredibly prone to strong winds, and low-growing moorland vegetation offers little defence; indeed it is the wind that ensures it remains close
to the ground. Fortunately, there are some plants that willingly accept these sorts of conditions.
Brachyglottis (Brachyglottis) This grey, felt-leaved, evergreen shrub is good for exposed, coastal places, as it tolerates salt spray. Brachyglottis ‘Sunshine’ AGM has yellow daisy flowers throughout summer and good foliage. Brachyglottis monroi AGM has a slightly denser habit. USDA Zone: Z8
Butterfly bush (Buddleja davidii) This is a deciduous shrub, loved by butterflies and other nectar-loving insects. It does not mind wind or salt, and seems to thrive in cracks in paving and walls. Spikes of pink, purple or white blossoms appear amongst medium-green foliage. It can reach 15ft (4.5m), unless pruned. USDA Zone: Z5
Gorse (Ulex europaeus) Gorse is a common shrub of lowland heath, with deep yellow flowers for much of the year. It survives on poor, impoverished soil and in full sun. It makes an effective and decorative barrier plant. Try the double-flowered ‘Flore Pleno’ AGM. USDA Zone: Z6
Heather (Erica spp and Calluna spp) These are useful, tough plants, most of which require an acid soil in which to thrive. Winter-flowering types include forms of Erica carnea and E. x darleyensis (the taller-growing ‘tree heathers’). For heathers flowering at other times, try: E. vagans (early summer to mid-autumn). USDA Zone: Z6–10
Purple moor grass (Molinia caerulea) This grass comes from areas of damp, acidic moorland, but it is happy in most average to moist soils in sun or part shade. Molinia caerulea subsp caerulea ‘Variegata’ AGM makes attractive, tough little tussocks with yellowish stems. USDA Zone: Z5
Wild rhododendron (Rhododendron ponticum) This plant is easy to grow in light shade and moisture-retentive, acidic or peaty soil. It has shallow roots, however, and so is not good for dry, sandy soil and desiccating winds. There are hundreds of forms, mostly spring-flowering. USDA Zone: Z5–9
Tough garden plants
Disc-leaved hebe (Hebe pinguifolia) This is a prostrate, evergreen shrub with tough, oval leaves making wide ground cover. It is decorated with small heads of pure white flowers for several weeks in late spring and early summer, for example ‘Pagei’ AGM. It is much hardier than most of the taller Hebe hybrids. USDA Zone: Z6
Elder (Sambucus nigra) Although this quick-growing shrub or tree can be pruned severely annually, it will reach 20ft (6m) in height. It is best in a mixed planting or as part of a hedgerow. Cream-white flowers appear in early summer, followed by black berries. The form ‘Aurea’ AGM has golden yellow leaves. USDA Zone: Z5
Flowering currant (Ribes sanguineum) Ideal for a poor clay soil, this is a tough, deciduous shrub with clusters of pink flowers in spring. There are numerous named varieties. Look for ‘Pulborough Scarlet’ AGM (intense pink), ‘King Edward VII’ (slow growing and deep red) and ‘Brocklebankii’ AGM (pink flowers and golden foliage). USDA Zone: Z6
Gardeners’ garters (Phalaris arundinacea) Also known as reed canary grass and ribbon grass, this plant looks vibrant in silver, white and grey. If cut down when it looks slightly tired, it will produce a second crop of foliage for interest through the winter. ‘Feesey’s Form’ – white leaves with narrow, green stripes – is arguably the best. USDA Zone: Z4
Mexican daisy (Erigeron karvinskianus AGM) Originally from Mexico, this plant spreads across the ground and soon starts seeding itself into all sorts of odd spots. It has intricate, light green foliage and daisy flowers in long succession. USDA Zone: Z7
Mountain ash, or rowan (Sorbus aucuparia) With a height of up to 50ft (15m) in some cultivars, this is not a tree for all gardens. But it is incredibly tough. Large, hanging clusters of orange-red fruits in autumn are the main feature. USDA Zone: Z2
New Zealand flax (Phormium tenax) This evergreen perennial with arching, sword-shaped leaves makes a good focal point in a garden. Stout stems carry tight handfuls of dull red flowers. There are many varieties with green, yellow, cream, white, pink, red and purple leaves. One of the deepest forms is ‘Atropurpureum’. USDA Zone: Z8
Pampas grass (Cortaderia selloana) This plant is much used, often unwisely so, in small gardens. Clumps can reach 6ft (2m) across, with flower spikes reaching heights of 10ft (3m). Plants make a dense tussock of leaves topped by shaggy plumes in late summer and autumn. Well-drained soil in an open position is needed; examples are often found growing on the shoreline. USDA Zone: Z5
Red hot poker (Kniphofia spp) These popular summer-flowering perennials are extremely windproof. They produce large rosettes of pointed leaves, although there are some diminutive forms with delicate, thin leaves. The poker-shaped flower heads are in shades of light yellow through to deep orange. USDA Zone: Z5–7
Sea holly (Eryngium maritimum) There is nothing quite like the sea hollies, with their electric blue flowers. These thistle-like plants are hardy and cope well with wind. A well-grown specimen stands out in any border. Other excellent forms include E. giganteum AGM, E. x tripartitum AGM and E. x oliverianum AGM. USDA Zone: Z3–5
Spanish broom (Spartium junceum AGM) This is considered ‘weedy’ by some gardeners, but it is a quick and easy small shrub that will help to fill gaps while slower, more prestigious shrubs are getting established. It has green stems and bright golden flowers, often coming in profusion. It withstands gales well. It prefers the sun and may be harmed in severely cold situations. USDA Zone: Z8
White-stemmed bramble (Rubus thibetanus AGM) This is a real toughie, but quite a dashing one. It is mainly grown for its winter stems, which glisten silvery white. The soft pink flowers are like small single roses, tucked in among the glossy, dark green foliage, which is white underneath. Black fruits appear in autumn. USDA Zone: Z6