Slug fences and slug collars are environmentally friendly methods that succeed in repelling slugs. In the following, we will give tips for how you can do-it-yourself.
We invest a lot of effort and time in our beloved garden and are only too happy to share the joy it brings us with others. Housing snails are welcome, because they usually consume only withered leaves and other parts of the plant, which are no longer quite crunchy. With slugs, on the other hand, we share the beds rather reluctantly. They passionately nibble fresh plants and fruits overnight. This makes for nasty surprises in the morning. You can counteract this in an environmentally friendly way with slug fences and slug collars: these keep slugs out while keeping them alive.
How do snail fences and slug collars work?
For the explanation, it is worth looking at the locomotion mechanisms of the slug. It moves along with an undulating motion of the sole of its foot, gliding on secreted mucus. This creates a vacuum, which is why it can climb up smooth surfaces. This adhesion mechanism is disturbed by a smaller contact surface. Snail fences and snail collars take advantage of this. Due to their special geometric shape, the material is so narrow that slugs rightly fear that they will not find a foothold. Namely, the edge of the fence is bent double at the transition of the bend at an angle of 90°, posing a danger to the animals. The slugs therefore avoid passing through these obstacles – especially upside down, so as not to challenge gravity.
Using slug fences as slug repellent
Slug fences surround an entire bed and serve as a slug barrier. To get inside, snails would have to overcome this obstacle. However, this is difficult because of the previously described structure of the snail fence – as long as care is taken to avoid gaps in the snail fence and also to avoid plant parts hanging over the slug barrier, which would act similar to a bridge.
Tip: By the way, one can also use plants against snails. These are plants that are slug deterrents and sometimes even drive them away.
Advantages and different forms of slug fences
Snail fences made of metal – also called snail sheets – and snail fences made of plastic are commercially available. Although those made of galvanised sheet steel are expensive, they do not rust, withstand all kinds of loads and therefore last for ages. Snail barriers made of plastic are cheaper; however, these quickly become porous due to weathering – especially UV radiation – and withstand stress for less time. After one season, they are often already broken and need to be replaced. In the process, it is not uncommon for them to leave behind a few small, unwanted pieces of plastic in the bed.
Metal slug fences
Metal snail fences come in a variety of designs, usually 20 or 25cm high. Some require additional corner elements to connect the long side panels, others do without them. Plastic models can be self-made from foil or purchased as a complete fence with variable modules.
Mesh slug fence
A wire mesh snail fence is flexible and bendable. Therefore, these snail fences can be easily shaped and can be used prima even for non-rectangular beds. Unlike solid materials, wire mesh does not cause water retention. Depending on the culture – whether the water requirement is high or rather low – the watering behaviour must be adjusted. Choose a narrow mesh size, so that slugs cannot crawl through it. The meshes should not be larger than 5mm, after all, there are also very small slugs that fit even through tiny gaps.
Electric slug barriers
Like willows, beds can be protected with a kind of miniature electric slug fence. This consists of copper wire or strip with an applied voltage of around six to twelve volts. Electricity flows from a battery or accumulator or comes from a small solar module. If a snail touches the copper device, it receives an electric shock and retreats. For people or pets, the applied voltage is not dangerous in principle, but can certainly give a little scare. As long as the current is flowing, there is protection. Unfortunately, electric snail fences are prone to malfunction and short circuits – for example, due to rain or irrigation water – can occur.
Build a slug fence yourself
In the spring, when the ground is no longer frozen, you can complete the construction of a snail fence. First of all, you need to calculate how much of the desired material is needed. This depends on the size of the area to be protected. Therefore, measure the length of the border and note that the fence should be around 25-30cm from the outer planting. For models with additional corner joints, the number of these corners must be known.
Once you have obtained all the necessary materials, clear the bed of all snails before the construction. It is best to collect them in a lockable container that allows air exchange so that they do not suddenly return to the bed during installation. To eliminate the snails hidden in the soil, dig the soil a good 10cm deep. Feeders and sun do the rest. Then, prick the substrate with a spade at least 10cm deep where the fence will be fixed.
For the exact procedure of assembly, it is best to follow the manufacturer’s instructions. In any case, make sure that the slug barrier has sufficient stability and that it rests against the ground, so that snails cannot crawl under it. Finally, firmly press the soil on both sides of the fence. Take one more control look over the bed to make sure that there are no slugs left.
Overview – Build your own snail fence:
- Measure the perimeter of the bed
- Note edge with 25-30cm distance from planting
- Collect snails
- Digging bed against slug’s eggs
- Pre-cut bottom 10cm
- Assembly according to the manufacturer’s instructions
- Observe stability and ground closure
- Press down the ground around fence
Slug collars and slug protection rings
Unlike a fence that is placed around an entire bed, slug collars protect only individual plants at a time, and only up to a certain size. Such slug collars therefore help especially susceptible young plants and can be removed later – when the plants are strong enough.
Advantages and types of slug collars
Just like snail fences, snail collars are also available in metal and plastic and have corresponding properties. Their mode of action is also based on the same principle. A special feature of the slug collars is that they can also be converted into a mini greenhouse. Since they are quite small, a lid can be placed on the opening, protecting the plants from frost, drying or heavy rain. An upgrade is possible with close-meshed fruit and vegetable protective netting or fly screens, which also keep out other garden animals.
Those who do not want to build a large slug fence or put umpteen slug collars in the bed, or who still want protection after such slug barriers have been removed, can resort to another means. These are slug pellets, which permanently eliminates these pests.
Make slug collars yourself
The easiest way to succeed is to make your own snail collars from old buckets. These should be transparent, if possible. This is especially important for young plants, otherwise they would be in the shade for a long time. For larger plants, which already protrude over the edge, impermeable bucket causes less problems. A bucket at least 12cm in diameter is suitable for most small plants. A height of about 15 to 20cm guarantees that the vessel can be put into the ground. For larger plants use larger buckets. For example, those used for bird feed are suitable for this.
Once you have found the right bucket, remove its bottom. The lid, if present, is best kept, as it can still find use later. Since the bucket is unlikely to have a suitable rim like that of a commercial slug collar, fruit and vegetable netting or fly screens can be stretched across the opening and attached to the bucket. Now you just need to put the shelter around the plant and press the soil. Make sure that no plant parts create a bridge over the edge into the interior, otherwise the snails will find a way to the covered garden buffet after all.
The craftier among us can also try their hand at edging their own snail collar or fence from sheet zinc. Those who have an edging bench can make excellent use of it. Otherwise, a hard edge, a large hammer and some patience is required. The sheet should not be too thin, otherwise it will bend under load. 1 – 1.5mm gives sufficient stability but can also be machined. In height, the sheet should measure a good 20cm. The double edge consists of two single edges of 45° each. The outer edge must face inwards towards the standing wall, as can be seen in previous pictures.