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Coastal gardens
Introduction
Whether you want a riot of flowers or to make an architectural statement, you can still create a coastal garden. Here's how.
In this report, we reveal strategies for successful seaside gardening, complete with planting and maintenance advice, and recommended plant lists.
The basics
Pros and cons
For gardeners there are advantages to having a garden near the coast. Temperatures are generally more amiable near the coast as the relatively warm sea mass reduces the risk of frost. But there are problems to contend with - salt-laden gale-force winds, bright sunlight, drought and often less than ideal soil conditions.
Generally, the closer you are to the sea the more limited the plant range but there's still plenty to choose from - trees, shrubs, perennials and annuals, both flowers and foliage. You may not be able to grow azaleas and Japanese maples but you can still have an attractive garden.
Dealing with salt
Gales can carry salt several hundred metres inland. Most of the plants mentioned here can cope with some salt, but occasionally a storm can dump enough salt to burn severely the foliage of even tolerant plants. This can happen when there's continuous wind with no rain. You can reduce the risk of damage by hosing the foliage. If your windows are coated with salt, your garden could probably do with a wash-down too.
Lawn
It's difficult to have a good lawn near the coast unless you're willing to provide an endless supply of water. Buffalo grass and kikuyu are tough hard-wearing grasses that do well in warmer areas. You can't buy them; they generally just turn up as "weeds" in existing lawns. Be warned that buffalo grass can spread, however.
Fruit and vegetables
Fruit trees like olives and feijoas are tolerant of some wind, but citrus and most others need good shelter and regular water to do well. In some areas lack of winter chilling and perhaps a shortage of bees for pollination could result in poor crops from pip and stone fruit varieties. You can grow most vegetables, though you'll probably have to apply plenty of organic matter, fertiliser and water to get good results. One advantage of being near the coast is that fresh winds and salty air can reduce the chances of pest and diseases compared to humid inland areas.
Our How To Guide
1. Choose the right plants
Plants that do well near the coast have built-in protection from the bright sunlight, harsh drying wind, salt spray and other adverse conditions. Some, like echium (pictured right), have fine hairs on their leaves, giving them a silvery or grey appearance. Others, like taupata, have a thick, waxy cuticle, giving a reflective shine to both stems and leaves.
Succulents store water in their leaves and stems while other plants, like bulbs, lie dormant beneath the surface to weather out drought or cold, bursting forth only when conditions are favourable. And some, like the native grasses, have narrow leaves, less prone to drying and damage in strong winds.
2. Provide shelter from the storm
Wind can damage leaves and in severe cases stunt growth. Even the toughest varieties grow better given some shelter. Avoid creating solid barriers, though. They simply deflect the wind up and over, causing turbulence on the leeward side that can sometimes be more damaging than the original wind. Ideally a windbreak should be 40-50% permeable. The idea is to reduce the force of the wind rather than change its direction.
If space permits, start with a mix of low-growing plants such as grasses, shrubs and flax (Phormium) to break the initial force. Follow this with taller shrubs and small trees. A planting like this may, however, occupy at least three or four metres and few gardens can afford this loss of space, so a fence or wall is often more appropriate. Build your fence with gaps (of up to half a slat width) between each slat. Break up a solid wall with gaps at regular intervals, closed in with trellis or some other permeable material. If you already have a solid barrier you can fix trellis along the top and train a tough climber like bougainvillea, ivy-leafed pelargonium or Campsis radicans over it to break the force of the wind. The filtering effect usually extends for a distance of four to six times the height of the windbreak.
Leave gaps between shrubs and trees, or windows in fences, to frame views from the garden. Create further calm areas elsewhere in the garden with plantings of shrubs and trees, low hedges, or structures like a climber-clad pergola.
3. Add organic matter
Soil around the coast varies greatly. It may be sandy, clay or even stony soil over a rock base. Poor soil structure, lack of organic matter, low fertility and low soil moisture are usually the main problems you have to contend with. Tackle all these problems in one go - apply generous amounts of organic matter, ideally to already damp soil. The easiest way is to mulch with compost, bark or other organic matter. Lay it 6-8cm thick, leaving a gap around stems and trunks to avoid collar rot. At first it may seem to disappear quickly, especially in damp conditions, but as plants become established and create shade the mulch will last longer. Alternatively, choose plants from our list that are suitable for extremely exposed sites. They'll tolerate particularly poor soils as long as they're not waterlogged.
4. Give new plants special attention
Ideally, plant in autumn or early winter. The soil is usually moist then and should remain so for several months, allowing good root growth before the stresses of summer. In sandy and stony conditions you can mix organic matter with the soil at planting time. If there's a choice at the garden centre select small plants rather than large ones of the same species. Not only are they cheaper but they often survive better in adverse conditions and soon reach a comparable size.
Plant in groups for mutual shelter, or provide temporary shelter with windbreak fabric, brushwood or the like. Stake plants if necessary to prevent the root system rocking in high winds. You can place stones or driftwood around the plant to anchor it as well as to shade the soil.
Water well immediately after planting and apply a generous layer of organic mulch, or use gravel, stones or crushed seas shells. Check regularly - you may have to water occasionally until plants establish.
5. Regular maintenance
Keep weeds under control - they use precious water and nutrients. Top up mulch as often as practicable.
If growth is poor apply fertiliser, but not to members of the Proteaceae family, such as proteas and leucadendrons. Sandy soils have little ability to hold nutrients, so use slow-release or general garden fertilisers that provide nutrients for some time rather than readily soluble or liquid types. Ideally, apply in spring or autumn when the soil is moist. Only water if really needed and then, to discourage surface rooting, make sure the water penetrates deeply into the soil.
Plants we recommend
Plants for extremely exposed sites
All tolerate sun except where indicated.
[*] = Good where soil erosion is a problem.
(a) = Muehlenbeckia australis can be an invasive weed in some areas.
| Trees and medium tall shrubs | |
| Botanical name | Common name |
| Aloe arborescens, A. thraskii | Aloes |
| Banksia integrifolia | Coast banksia |
| Pittosporum crassifolium | Karo * |
| Myoporum laetum | Ngaio * |
| Lagunaria patersonii | Norfolk Island hibiscus |
| Olearia traversii, also O. paniculata | Chatham Island akeake |
| Metrosideros excelsa*, M. kermadecensis* and hybrids such as 'Spring Fire' and 'Vibrance' | Pohutukawa * |
| Coprosma repens* and cultivars | Taupata * |
| Tamarix spp. | Tamarisk |
| Low shrubs, groundcovers and perennials | |
| Arctotis, Gazania, Osteospermum and Dimorphotheca cultivars | African daisies * |
| Westringia fruticosa | Australian rosemary |
| Brachyglottis 'Sunshine' (previously sold as Senecio greyi) | |
| (Phormium tenax and P. cookianum) | Flax * |
| Drosanthemum and Lampranthus spp. and Disphyma australe | Ice plants * |
| Beschorneria yuccoides | Mexican lily * |
| Muehlenbeckia spp.* (a) | |
| Silene uniflora | Sea campion |
| Crambe maritima | Sea kale |
| Coprosma acerosa, also C. prostrata, C. kirkii and C. 'Hawera' | Sand coprosma * |
| Agave, Aeonium, Echeveria and Sempervivum spp. | Succulents (see picture) |
Plants for less exposed sites
These plants also do well if given a little shelter.
| Botanical name | Common name |
| Trees and medium-tall shrubs | |
| Cordyline australis | Cabbage tree |
| Pseudopanax lessonii | Five-finger |
| P. crassifolius | Lancewood |
| Corynocarpus laevigatus | Karaka |
| Griselinia lucida, also G. littoralis | Kapuka |
| Echium candicans (see picture) | Pride of Madeira |
| Meryta sinclairii | Puka |
| Eucalyptus ficifolia | Scarlet gum |
| Low shrubs, groundcovers and perennials | |
| Astelia chathamica | Astelias |
| Clivia (requires shade) | |
| Russelia equisetiformis | Coral plant |
| Euryops pectinatus, E. virgineus | |
| Lavandula dentata | French lavender |
| Clianthus puniceus | Kaka beak, C. 'Kaka King' |
| Convolvulus sabatius | Moroccan glory vine |
| C. cneorum | Bush morning glory |
| Choisya ternata | Mexican orange blossom |
| Leucospermum spp. | Pincushion flower |
| Xeronema callistemon (see picture) | Poor Knights lily |
| Arthropodium cirratum | Rengarenga |
| Cistus spp. | Rock rose |
| Rosmarinus officinalis | Rosemary |
| Bulbs | |
| Freesia, ixia, tritonia, nerine and sparaxis |
Plant pictures
| Plant | Picture |
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Fiery red arctotis - also comes in pink, orange and yellow |
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A mix of sun loving succulents - aloes, echeveria and crassula |
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Red bottlebrush flowers of Poor Knights lily and leucospermum in bud |
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Echium |
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