Do All Your Native Plants Need Special Fertiliser? Australian Native Plant Myths
When it comes to caring for native plants in the garden, plant nutrition is an often brought up topic. One of the most commonly spread bits of information about Australian native plants is that they require special ‘native fertiliser’, let’s unpack that.
Persoonia linearis a wonderful tall shrub in the Proteacaea family
Is there any truth to this?
Yes there is! Some native plants do in fact have special considerations around fertilisers; these are typically, but not exclusively, plants from the Proteacaea family. Your most commonly found plants in that family in the garden are grevilleas, telopeas (waratahs) and banksias although many others fall into that category like isopogon, macadamia, persoonia, stenocarpus, hakea and there’s a bunch more.
So why do they make special native fertiliser?
Risking falling into the same trap that leads to this idea with gardeners I’m going to make a broad statement here: Typically speaking Australia’s soils are naturally low in phosphorus, which is the P in NPK. Almost any fertiliser you buy will have an NPK ratio written somewhere on the packaging, most general purpose fertilisers will have relatively even values and some specific fertilisers will have more or less of one or another. Native fertiliser typically has low or no phosphorus content in it. Many of the above-mentioned genus of plants in the Proteacaea family and a few outside of that family have adapted to Australia’s naturally low phosphorus levels in the soil and have thus become sensitive to high levels of phosphorus. If you have those plants in your garden and choose to fertilise you will need to use a special low phosphorus fertiliser in order to keep your plants happy and healthy.
Critically endangered Grevillea rivularis
When do you need Native fertiliser?
You only need the special stuff if you have phosphorus sensitive plants in your garden.. To err on the side of caution I’d recommend using low phosphorus native fertilisers if you have anything in the Proteacaea family especially if you know it to be sensitive like Grevlillea species in your garden and just use it across your whole garden to save buying multiple products as the low phosphorus won’t negatively impact other natives that aren’t sensitive. But if you don’t have any sensitive plants you don’t need to worry about special fertilisers, just get a general purpose or just use good quality compost and mulch well. A quick google search will often give a pretty good idea of whether a plant is sensitive or not.
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Telopea speciosissima flower starting to open.
