By Drew Cooper
We are often asked what indigenous trees are suitable for introducing into a landscape on the Mornington Peninsula. Generally, plants are classified based on soil and pH rather than just broad location. Within a 20-minute drive you can move from calcareous beach sand to heavy grey clay to crumbling red loam, and the indigenous vegetation that evolved on each of these soils is markedly different.
Understanding which soil type you are actually working with, rather than guessing from a general sense of ‘sandy’ or ‘clayey’, is the single most useful piece of information for choosing plants that will not just survive but thrive without ongoing intervention.
Starting at the coast, calcareous sand dominates the tip of the Peninsula from Portsea and Sorrento through Blairgowrie and around to Rye and Rosebud. This is coastal alkaline scrub and coastal dune grassland country, and the backbone species reflect it. Moonah (Melaleuca lanceolata), coast banksia (Banksia integrifolia) and drooping she-oak (Allocasuarina verticillata) handle the alkalinity and the exposure well and were historically dominant across these dune woodlands. Beneath them, coast beard-heath (Leucopogon parviflorus), coast wattle (Acacia longifolia subsp. sophorae) and coast tea-tree (Leptospermum laevigatum) provide the larger shrub layer.
Move inland from the immediate coast and, particularly across the northern part of the Peninsula around Cranbourne, Langwarrin, Pearcedale and Baxter, you hit dark grey acidic soils above what we commonly call coffee rock. Suitable plants will need to handle less well-draining soils. Silver banksia (Banksia marginata), common heath (Epacris impressa) and a wide range of indigenous grevillea and hakea species do well here.
Heading south from Dromana and across through Moorooduc and Tuerong to Bittern and Langwarrin, the soil changes again from yellow duplex to the slightly better-draining brown duplex. Manna gum (Eucalyptus viminalis) and swamp gum (Eucalyptus ovata) do well on the damper margins, woolly tea-tree (Leptospermum lanigerum) suits the seasonally moist pockets, and sweet bursaria (Bursaria spinosa) on the better drained soils.
The most fertile ground on the Peninsula by a wide margin is the deep red volcanic soil found around Red Hill, Main Ridge and Arthurs Seat, where the soils are a reddish clay loam. Messmate (Eucalyptus obliqua) and blackwood (acacia melanoxylon) are the dominant trees here.
Matching plant choices to soil is less a matter of taste than of long-term survival. A banksia planted into a fertilised, phosphorus-rich garden bed derived from imported topsoil will decline regardless of how well it is watered, just as a blackwood will struggle on calcareous dune sand and will never achieve the form it would on the red volcanic country around Red Hill.
Taking the time to identify which of these broad soil types you are actually dealing with before selecting your trees will do more for long-term establishment success than any amount of soil amendment applied after the fact.
You can find some good resources online that will help you determine which soil category you may have. The Mornington Peninsula Shire Common Ground factsheet and Native Plant Guide are worthwhile consulting, while the Mornington Peninsula Landcare Network and SPIFFA have some invaluable information.
Happy gardening!
Peninsula Plants Nursery
peninsulaplants.com.au
