By Megan Backhouse
Some gardeners ply their plants with sugar and honey. Others coax them along with coffee grinds, used tea leaves, crushed eggshells or even fish heads. Shaun Micallef remembers his aunt feeding bananas to her Staghorn Fern. The way he describes it, you imagine her peeling the fruit and feeding her prized Platycerium superbum like a pet chimpanzee.
"Even as a child, I wondered about the moral implications of a plant eating another plant," he says. "Can plants be cannibals?"
The Staghorn fern is partial to banana, but are there any moral implications?Credit: Getty Images
If that means feeding off another plant – even of the same species – you would have to say yes. Mind you, it is not always so baldly as the way a staghorn fern traps falling vegetable matter in its nest fronds.
Many of us spike our garden beds with compost (largely decayed vegetable matter), dowse them with teas (made by soaking plants in water) and insulate them with mulch (often plant-based, such as sugarcane, pea straw, or pine bark). As well as helping to improve moisture retention and aerate the soil, plants can then absorb some of the resulting nutrients through their roots.
A 1920s postcard of the Temple of the Winds, with its its staghorn-fern topped columns.
Staghorn Ferns don't live in soil, which can complicate composting and mulching. Native to lowland rainforests in Queensland and northern New South Wales, Platycerium superbum are epiphytic (growing on trees) or occasionally epilithic (growing on rocks). It is the same for other Platycerium species, including those native to South America, Africa, South East Asia and New Guinea.
Not being parasitic, staghorn ferns don't feed from their host but attach themselves in such a way that the sterile basal fronds create a bowl form. This is big enough to catch falling leaves and other plant detritus, including – with the help of a doting owner – banana treats.
The thinking behind this is that bananas – either the peel, the fruit itself or water that has had been infused with banana peel – can contribute potassium, phosphorous and calcium, thereby improving frond growth. Some people also swear by tucking banana skins between the plant's basal fronds and its mounting board or other support structure.
Others suggest that growers should allow their banana scraps – along with other organic waste – to decompose in a properly maintained compost heap first so that their nutrients are more readily available to the fern. I can find no scientific evidence for the benefits of uncomposted bananas. Indeed, a recent University of Melbourne study found adding uncomposted coffee grinds to soil can actually decrease plant growth. Some horticulturalists are also questioning the nutrient and microbe levels of compost tea compared with straight-up compost.
The underside of a staghorn fern.Credit: Getty Images
Either way, what gardeners are courting with their staghorn-fern feeding are luxuriant-looking antler fronds, from which the plant gets its name. The late Bali-based garden designer Made Wijaya described these pendulous and beguiling fronds as "the drop-earrings and handle-bar moustaches of the plant world". You only have to look at the Royal Botanic Gardens' 1901 Temple of the Winds, designed by William Guilfoyle, with its staghorn-fern topped columns to see how ornamental they can be.
The antler fronds are also the fertile ones and have spores on their underside. It is only through the germination of these spores that you can propagate new plants as the Platycerium superbum (unlike Elkhorns, or P. bifurcatum) don't generate "pups".
Australian gardeners have been cultivating all sorts of ferns since the mid-19th Century, with horticultural journals offering advice on shade houses for ferns, including Australian Platycerium species, from the early 1880s.
But just as mounted antlers have been spreading beyond the confines of the hunting lodge, staghorn ferns have moved into all manner of settings. With their habitat of choice being warm, humid forests, they like filtered light, good air movement and protection from wind and hard frost.
Over-watering is one of the most common causes of staghorn-fern death and they like to be kept relatively dry in winter, especially when young, as with minimal root systems, they are prone to rotting. Water them about once a week in summer.
Feeding them bananas is optional.