A wide diversity of wildlife is usually a good thing in a garden. From birds to bugs and even amphibians, a thriving eco-system is a useful sign of underlying health and sustainable practices.
But not all visitors are equally welcome. While possums may have a certain charm, their adventures in a garden can be highly destructive, quickly driving a gardener to distraction.
As they're nocturnal foragers, you might never see your marsupial guests in the flesh. But if you have a few enthusiastic visitors, you'll certainly see the damage they can do to your carefully tended veggie patches and flowerbeds.
Possums' Eating Habits
Possums make a beeline for fresh, juicy young growth, favouring everything from flower buds to vegetable seedlings. Being accomplished climbers, they’re particularly fond of dining on tree fruits, feasting in peace up in the branches.
But the problems caused by possums don't end with plant decimation. In their hunt for food they can overturn rubbish bins and compost heaps alike. They can send container gardens into disarray, knocking over pots as they search for the bugs and worms with which they supplement their mainly plant-based diet.
And lastly, they're capable of leaving behind copious amounts of droppings as a final insult to the tidy-minded gardener.
But for all this nuisance value, possums are well-loved by most people, and are also protected under the Wildlife Act of 1975. This means any deterrent action which harms the creatures is illegal as well as unethical. So how do you deal with a possum problem in your garden?
While possums love young and tender growth, they're less keen on ageing plants, particularly tough or prickly ones. You can use this natural aversion to your advantage, by making access to your seedlings, shoots, and fruit more difficult.
If your plants are under immediate attack, scattering old rose cuttings or similar sharp materials across the earth can add a discouraging barrier, as can poking twigs and canes into the ground to create a spiky mini-forest.
Standard bird-proof netting offers good protection for beds and shrubs, but be sure to use one with enough strength to resist gnawing teeth. Alternatively, for tree fruit, use string or a plastic tie to attach an exclusion bag around the ripening fruit to offer a little protection and concealment.
Importantly, any netting or other physical barrier you use doesn't need to be permanent. As possums are only active at night, you can fix netting at dusk to provide overnight protection, then remove it in the morning to allow access for watering, weeding, harvesting, etc.
Possum Deterrence Using Strong Odours
Possums appear to have delicate tastes when it comes to strong odours. Menthol rubs, perfumed detergents, and even mothballs can deter them when spread around their regular haunts.
However, adding chemical substances to your garden may go against the grain for organic gardeners - and it's not necessarily good for the possums either.
Nonetheless, possums' distaste for smells can be used against them in a much more natural way. Combine some of the contents of your spice cupboard with a large garden sprayer, and you can produce an effective homemade deterrent.
For a starter mix, simply stir two tablespoons of chopped garlic into two litres of boiling water, and leave to steep overnight. Strain, pour the liquid into your sprayer, and liberally coat the plants which the possums are most attracted to. Repeat the spraying after rain, or when the smell starts to noticeably fade.
Upping the Ante
Unfortunately, possums are highly adaptable. They have been known to develop a tolerance - or even preference - for garlic. If your garlic spray is becoming less effective, you can up the ante by making a similar spray using chopped, fiery chillies.
And if even this concoction doesn't work, quassia may offer an unusual spicy solution. This bark is so effective at deterring possums that it forms the basis of several commercial organic products.
Boil 100g of quassia chips in 2 liters of water for one hour. Dilute to a quarter-strength, add a tablespoon or two of horticultural soap to help the mixture stick to its target, and spray where required.
Lastly, almost anything with a pungent smell has probably been used against possums by one gardener or another. You may find that any or none of the following odorous sprays are ultimately offputting to your local possum population.
- Fish oil or fish sauce.
- Hot English mustard.
- Tabasco sauce.
- A strongly brewed tea, ideally Earl Grey or Lapsang Souchong.
Making Access Difficult
But for longer-term success, making access to your garden physically difficult is the best approach. Possums are creatures of habit, and if their favourite entry points are made more inaccessible, they'll often move on for an easier life.
Secure the perimeters of your garden using wire mesh rather than a solid fencing. Possums are excellent climbers, but prefer climbing on a stable structure. Anything a little shaky or wobbly will deter them more effectively, so a relatively loose mesh is ideal.
If this type of physical protection isn't to your tastes, a natural barrier formed by highly perfumed plants such as lavender, rosemary, or citronella can be useful. Place hedges of these species around your vulnerable areas, and use them to block any regular possum runs you've identified.
You can make this method even more effective by backing it up with another stink-bomb solution, such as a heavy mulch of blood and bone fertiliser spread around the base, which repels possums as it starts to rot down.
Other Physical Deterrents
If possums view your garden as a playground, you'll find it difficult to dislodge them. Setting as many obstacles in their way as possible may tip the balance and encourage them to find more comfortable places to spend their time.
- Place possum-proof clear plastic bands around tree trunks, making climbing more difficult without spoiling appearances.
- Fix homemade or commercially available deterrents (spikes or rollers) onto the tops of fences and walls, to unbalance the possums as they enter.
- Suspend netting between trees and garden structures, to stop them jumping from place to place in safety.
- Install motion-detecting security lighting to provide a midnight fright.
- Some people find sonic deterrent devices to be effective, although they can also have an impact on household pets (and even some younger people with acute hearing).
- Fill in any existing burrows, tree hollows, and other potential resting places after making sure they're unoccupied. Possums are opportunist homemakers rather than burrowers, and removing ready-made lodgings will tempt them to move to easier residences.
Possums can cause havoc in a garden, but realistic gardeners know fighting them isn't a battle that can be completely won. Making life difficult for them without causing them harm, and so keeping the damage they cause to a minimum, is perhaps the best you can hope for.
And if you can bring yourself to be generous about the subject, remember that a thriving possum population is a sign that your garden is healthy, fertile, and making a valuable contribution to the ecological diversity of your area.