Why coastal Sydney gardens struggle
Salt-laden onshore wind burns tender new growth, and the sandy soils common along the Northern Beaches drain so fast that water and nutrients leave the root zone before plants can use them. Fighting the wind plant by plant rarely works — a windbreak of genuinely salt-tolerant species does more for the garden behind it than any amount of individual coddling.
What tends to hold up
Coastal natives such as banksia, westringia, lomandra and correa are reliable performers close to the water, alongside hardy exotics like agapanthus and various succulents. Further back from direct exposure, the plant palette opens up considerably.
Feeding and watering for sandy, salty soil
Little-and-often feeding beats a single heavy application, since sandy soil can't hold nutrients for long. Building organic matter into the soil over time — through mulching and occasional soil conditioner — improves both water retention and nutrient hold.