Wildlife and Food Gardens

Most food gardeners realise that the land they live on would have been or still is part of Tasmanian wildlife's habitat, and that therefore it is not unreasonable to share some of the food you grow. In most cases, however, sharing with wildlife means that you get nothing, so establishing clear boundaries is the only way to grow food and enjoy the fruits of your work. This blog post discusses effective fencing options that will make growing food wherever you live in Tasmania completely feasible!

Rosalie's food garden enclosure at South Hobart (Dec21)

The most common wildlife threats to your produce

Your uninvited eaters may be diggers, such as rabbits, potoroos or bandicoots. 

Your uninvited eaters may be climbers. Possums can jump up to 1.2 metres vertically. There are other native animals such as quolls that also fit in this category.

Your uninvited eaters may be wallabies, for which fences will have to be extra sturdy and ideally electric, so animals are discouraged from using their force to crash through.

Your uninvited eaters may be birds. They may be stealing your berries and eat your fruit. Or perhaps you may want to invite birds to your veggie garden because they eat caterpillars and other garden pests.

Below you will find strategies for dealing with these four categories of wildlife.

General design considerations

It might be a good idea not to build one fence or netted are around your whole garden, but fence individual food-garden areas, so if one area is ever breached, not your whole garden is exposed.

You could decide to have one fence for your veggie garden and another fence for an area where you grow fruit and berries. Your veggie garden may have fences that keep out diggers, possums and/or wallabies, but no roof, so birds can come and go. You may need more protection for your fruit and berry area, so all wildlife including birds are kept out. Alternatively, you may chooses to fence in individual fruit trees.

Consider making your fenced food-garden area(s) slightly bigger than what you need at present, so if you want to expand later on you can do so without having to put in more fencing.

Never use barbed wire. Each year many animals face a cruel death or permanent injury from entanglement on barbs. Barbed wire is really not needed.

A really effective, alternative way to keep wildlife out of a fenced food garden, is to have a dog inside it at night. If you have a robust farm dog and provide a good kennel, this can work well for both you and the dog. The wildlife will smell the dog, and that alone can be a really good deterrent. 

Whatever wildlife deterrent you decide to put in place, it is much more rewarding to spend the money, do the job once, and do it well, than to try and not spend much, and become frustrated, when your crops are still eaten.

Option 1 - Easy to install protection against occasional intrusions

If you only have a few food-garden beds, poly-tunnels with netting will keep birds and the occasional mildly-interested ground-animal out. 

Poly tunnels are made by driving stakes into the ground and attaching poly pipe to them. The best stakes to use are reo bars (re-enforced metal bars for use in concrete). They sell 1.8 metre long 12mm. thick reo bars at hardware stores. You will also find them at tip shops. Allow 1.5 metres between the arcs. 

If you have the room, make the tunnel a bit wider than the actual garden bed, so plants can grow outwards without pushing against the net.

For the arcs you can use cheap thin poly pipe that is used for irrigation. However, 25mm (1 inch) diameter poly pipe (for instance Vinidex at Bunnings) is much stronger. It will not distort and kink in high winds and will cover a slight wider space.

It helps to have hard surfaces as the boundaries of your net because then you can use bricks to make the area inaccessible for diggers.

The further off the ground your garden bed is, the less chance there is that wildlife will get in. Small rodents may find the slippery surface of galvanised garden beds hard to scale. Small rodents don't like to be above ground level because that makes them too visible. 

It is one of the reasons why off-the-ground raised food garden beds, in some cases complete with inbuilt wicking facility and net (photo below), are becoming quite popular. For more info on what wicking is, see How to build a wicking bed on this blog. 

The beds in the photo above are made by Vegepod - see https://vegepod.com.au/collections .

These beds are a great (but not cheap) option for growing vegetables, especially for people who have difficulty bending over. Netting, and the fact that your vegetables are well above ground level, provide some protection against animal intrusions. 

Determined possums have been known to completely trash all the structures discussed above.

Option 2  - Robust structures that let the birds in

Floppy fences are used successfully by many people.

A good floppy fence works as follows: as a possum (or quoll etc) attempts to climb the overhang, the mesh bends down. The possum lets go and falls to the ground. The floppy top springs back to its original position, ready for the next attempt.

In the photo above star-pickets are positioned at an angle against fence posts and used to extend the wire-mesh beyond the fence line.  Horizontal wires re-enforce the wire-mesh across the star-pickets, but not the wire-mesh beyond the end of the star pickets, so the top become 'floppy'.  The builder of this fence commented that, if she would build this fence now, she would make it 1.8 metres high.

The wire-mesh in most floppy fences springs back to its original position because it has a 'high-tensile support wire' (see diagram below):

Other Food Garden Group members built floppy fences using a somewhat simpler but effective interpretation of the high-tensile support wire:

 

The choice of wire-mesh is important.  For the floppy top part choose the smallest gauge mesh that holds itself up, but is flexible enough to spring back.  The mesh in the photo has 50mm x 50mm holes and is 1mm thick.  It 'flops' effectively.

Posts are another point to consider.  Some people use star-picket posts and they are fine, but treated pine posts, properly anchored, allow much better tightening of wires. 

Proper posts make easier entry points for climbers.  The diagram above shows what to do on corners ('shape of wire mesh for corner insert').  Here is is an example:

With the help of support wires, the mesh is curled around this corner post so it becomes impossible to reach.  It is best for posts not to be higher than the wire-fence.  

Slippery fences are a different method to keep wildlife out. The photo below shows a large veggie garden surrounded by bush at Mount Nelson fitted with slippery fences.

Garden by Michael, Robyn, Tracey & Linda - photo by Laura - thank you!

Here is a close-up of a section of this slippery fence:

Slippery fences are reported to be very effective against possums and other climbers. Make your slippery fence around 1.5 metres high and start the slippery section at around 90 centimetres off the ground.

Option 3 -  Keeping all the wildlife out

Many food gardeners have large poly pipe cages in their gardens. They are easy to erect and the pipes you need are not expensive. The photo below shows a poly pipe cage I put in front of our hothouse. 

I drove star pickets into the ground as far as they wanted to go. For the arcs I used 2" rural poly pipe from an agricultural supply company (Hollander Imports). The width of the cage in this case is a bit over 3 metres. The wider you make a cage with these pipes, the higher the cage becomes, because this type of pipe does't bend easily.

I used 25mm Vinidex poly pipe (Bunnings) to keep the arcs in place at the top and sides. You need these horizontal braces to keep the structure from swaying in windy conditions.  I attached the 25mm pipes to the 50mm pipes with 11 cm. long galvanised iron bolts. Poly pipe is easy to drill, and if you make a mistake, you just drill another hole.

Members of the Food Garden Group with a bit more land and good building skills have over the years shown our group wonderful examples of custom-made completely-enclosed food gardens.

A great example, built by Food Garden Group member Mandy at Margate - complete with chook run and lights for working after dark - (see photo below), is described in detail in blog post A wildlife-proof garden on this blog.

Below is a close-up of a central post in such an enclosure.

Once a heavy net is stretched over them, there is a lot of pressure on poles in a structure like this. Consider putting each pole in a deep hole and concreting it in.  Bracing may also be necessary.

At Sandfly Food Garden Group members Russell and Jenny built a segmented cage down a slope. The cage is robust enough to cope with a layer of snow on its roof. It is covered in fine metal mesh that has holes big enough to let insects through.

Here is how it looks on the inside - notice the paving throughout.

One day I might devote an entire blog post to the many wonderful enclosures members of our Food Garden Group members have created.

The best nets for food gardens

Hardware stores may claim that the standard bird netting they sell is durable and bee-friendly, but  neither claim may be matched by reality. 

Steel reinforced netting is much more long-lasting - consider years of exposure to windy conditions. It can cope with the weight of wildlife, for instance possums, walking over it. It is also ideal for parts of Tasmania where snow settles on nets and its weight would tear ordinary netting. 

Food Garden Group members report very good results with bird-netting that is reinforced with thin metal wires (photo below). It is stainless steel 9ply reinforced bird netting. It is sold by a company named Haverford here. 

It is important to only use netting that bees and other pollinators can get through, so you don't hinder pollination of the crops inside the enclosure. 

It is claimed that bees and other pollinators can land, crawl through and then fly again, through holes of 5 mm. However, the question is will they bother if there is food elsewhere that is easier to reach. 

There is another point to consider here: crawling through netting can knock the pollen out of the pollen baskets where bees carry it, so you might be happy that your plants were pollinated, but the bee colony just lost several hours of labour and food.

For these reasons Food Garden Group member and beekeeper Laura recommends that the holes in bird exclusion netting are at least 7, but preferably, 12 mm. 

The mesh size of the stainless steel bird netting recommended above is 19mm x 19 mm. Food Garden Group members Pauline and Dirk have this netting and report that only the smallest birds (Blue Wrens) can get through this. Blue Wrens eat insects and seeds, so that is fine, as long as you put some mesh over spots where you don't want seeds to be taken.

It's important to have an effective gate

Gates or doors are often weak points in fenced garden areas because they may be easy to scale, or worse, they may be left open. Minimise opportunity to enter by giving each cage or fenced area just one gate.

It is easy to make mistakes when designing a gate or entrance door.  For a start, how about making it wide enough so your wheelbarrow will go through it.  So simple ....  if you think of it ....... at the time!

Attach a good spring to your gate, so it always closes behind you, but consider making it so that you can disable this spring when you have to go in and out of your enclosed area many times.

The gate below was covered with galvanised iron, nice and slippery - 'unclimbable'.  The ends of the sheet have been bent back so the edges are not sharp and again provide no grip.  Consider also having galvanised iron sheets either side of the gate, because these spots can also create access points.

The gate has a threshold so no one can dig under the gate.  

Keeping the diggers out

The best method of keeping diggers out of food gardens is to have, right around your fence line, a strip of fine-mesh wire, which continues below ground level and extends outwards horizontally to around 200mm outside your fence line.

Diggers will begin their work, get nowhere, and give up. You will find that after a while 'the locals' know and don't even try.

This strip of fine mesh also makes it unlikely that you will damage your netting if you use a line trimmer to cut grass along the fence. 

About electric fences

Some would argue that a good floppy or slippery fence does not need electrification, and they may be right.  Others feel that the added discouragement is definitely worth it.  Please realise that electric wire can fail (shot-circuiting in wet weather, power failures), so don't use it as your only line of defence.

Electric-fence lines can be completely separate from your mesh-fence line (photo below) or be part of your wire-fence line (photo further down).

The Little Farm market garden at Margate (see Visit Margate Little Farm 2023) is bordered by a floppy fence that is surrounded by an electric fence. The electric fence was bought from Hollander Imports. The electric fence is charged with a solar 'Fence Energiser' from Thunderbird Electric Fencing Systems (https://thunderbird.net.au/). 

 

Together with an effective gate this setup does a great job. Owners Marcus and Anna reported that the wildlife took just a few nights to get used to the electric fence being there. Now they no longer even try to get into the garden. The poos around, but not in, the garden show that there is plenty of wildlife around. Creating a robust deterrent, so wildlife realises it is futile trying to intrude, is working very well here.

If you take the different approach of adding electric wires to your wire-fence, it is critical that, horizontally, they are no more than 10cm from the mesh-fence, so the animal touches the electric wire while touching the fence ('earth') and therefore gets a shock.

An electric wire more than 1.2 metres from the ground so possums can not jump past it, may be the best approach.  Some people have two wires, one near ground level, and one on top of the floppy end.

Here is a simple and inexpensive method of attaching the electric wire to the fence:

In summary ........

If you happy to spend time and money to build a good robust structure, you can grow food and enjoy the rewards without the frustrations of constant wildlife damage, no matter where you live. Wonderful tasting produce will make your investment more than worthwhile.