I live close to the ocean along Australia’s east coast. I have some challenges to face growing a coastal garden.
These challenges are to do with soils, salt or both. The timeless forces of nature erode the rocks and move the fine granular particles northward, depositing these particles where convenient. Consider that Fraser Island, the world’s largest sand island at 120kms long and covering 1840 square kilometres is composed of almost all sand and considered to be derived from Hawkesbury and Hunter sandstones over a period of 750,000 years.
The predominant southeasterly winds continually blow the transported sand up into dunes as tall as 240metres. This makes it tough for plants to establish and thrive but they do!
Plants have to find nutrients and water in sandy soils in order to grow successfully. Rainwater percolates through the soil profile rapidly so native coastal plants may have extensive root systems and/or mechanisms by which moisture loss within the plant is minimised. These mechanisms include fine leaves, leathery or waxy leaves. Coastal gardening can be challenging, so look to use these plant species as a starting point.
Salt is the second challenge. All plants require salts of minerals to function but if the level of salts is too high or the wrong type then problems occur.
If your garden is front line to the ocean then you will experience periods when salt spray covers your plants and burn results on soft foliage. This can come from the magnifying effect through salt crystals or accumulated salts in the soil reaching a point where toxicity occurs. Different species have varying levels of tolerance. Once again, a safe approach is to use native plants found in your local area and to use other species which seem to be doing well. Pandanus, Leptospermum, Banksia and Lomandra species are good starting points.
When you migrate to the other side of your garden you will find much more protection and a wider range of plants can be used. One street back from the beach is a vastly differing gardening proposition! Take a look at the composition of natural plant communities near you to see the transition from dunes to back of beach; these back communities yield some beautiful species like Acmena hemilampra and other glossy foliaged gems.
Some of the most attractive gardens are those found in coastal locations where a disciplined approach is used and species are limited to a few. There is great beauty in the combining of plants which are in colour harmony with each other; the blues and greys together, without contrasting colours.
Select plants carefully, discipline the palette, add organic material to sandy soils and provide mulch to slow down evaporation. Feed with slow release fertilisers at the start of Spring and Summer and use fish emulsions as often as once a month to promote new growth.