The never-ending war with slugs and snails

Canna enthusiasts are well aware of the damage that slugs and snails can cause in their plants, and although the use of chemical slug repellents is a possible protection option, the preference is often towards more environmentally friendly methods, and that’s a good thing. So how can we win this war? Firstly, the bad news… we will never win, nature provides a never-ending supply of these repellant specimens.

Not all nighttime marauding is caused by gastropods. An easy clue to determine who’s causing the damage is by the telltale trail of shiny mucous they leave behind – if a slime trail is present, you know the culprit is a slug or snail.

In addition, in the overall balance of nature, slugs and snails are very important. They provide food for all kinds of mammals, birds, slow worms, earthworms, insects and they are a vital part of the natural balance. Upset that balance by removing them altogether and we can do a lot of harm. Thrushes in particular thrive on them!

Slug behavior and seasons of activity

Firstly, know your enemy. Slugs, characterized by their propensity to eat a large quantity of young leaves in particular, are particularly active during the more humid and temperate seasons. Their insatiable appetite leads them to feed on a variety of plants, which can cause considerable damage to gardens. These gastropod molluscs move mainly at night, hiding during the day to avoid heat and drought, but they can also be seen emerging after a nice shower during the day.

Six battlefield tactics

Understanding these seasonal rhythms and the enemies predictable behaviour allows us to anticipate and implement appropriate strategies, judiciously integrating repellent and attractive plants to maintain an ecological balance in the garden environment.

1. Firstly we can grow other plants alongside our cannas that slugs and snails find repellant, thus pressurizing them to move elsewhere.
2. We can do the exact opposite and grow plants that they find more attractive than our cannas, and they move out to our  controlled pastures anew.
3. Create physical barriers to stop them reaching your cannas.
4. Bait and trap
5. Attract Natural Enemies of Slugs/Snails.
6. Hand-picking (not everyone’s favourite tactic).

Let’s take a close look at these approaches for a natural and balanced fight against slugs, and very voracious gastropods that are best kept away from your plants. In order to obtain the best possible results, the gardener should not hesitate to combine different natural slug control methods.

Slug repellent plants

The key to the first tactic lies in the strategic use of certain plant species, which must be obviously repellent but also, as gardeners, they also have to be attractive.

These are plants that emit fragrances that are repellent to slugs, as a result, they act like a natural barrier. By introducing these repellent plants into the garden, you can easily influence the behavior of slugs by encouraging them to avoid very specific areas that you want to protect from their attacks.

As slugs are well known for their extraordinary appetite, the gardener has every interest in growing the following plants in every nook and cranny of his garden, especially if it is frequently attacked. I normally plant them in pots, smaller than the canna pots and stand them in between the canna plants.

1. Garlic: Slugs generally don’t like the smell of garlic. So simply install them around their favorite plants to keep gastropods at bay.
2. Rosemary: This aromatic is well known for its highly effective repellent properties. Rosemary will grow into quite large plants, so each year just take cuttings and create a new generation of young plants.
3. Sage: This medicinal plant keeps garden pests away. It does not require much attention, just water and a fertilizer pickup mid-season.
4. Geraniums: With their characteristic scent, they emit odorous compounds that slugs find unattractive. The strong odor of geraniums acts as a natural deterrent, prompting herbivorous molluscs to totally avoid areas where these plants are present. Of course, you have to also find these plants attractive enough to live with the scents.
5. Begonias: These plants have repellent properties due to their particular chemical composition. The substances emitted by begonias interfere with the senses of slugs, creating an olfactory barrier that discourages their presence in the surrounding area.
6. Onions: The very distinctive pungent odor of the onion acts as a natural repellent. This plant can be used strategically to protect crops susceptible to slugs, and is normally very successful.
7. Parsley: Characterized by its fresh scent and strong flavor, parsley emits odorous compounds that act as a deterrent against pests. Slugs find these strong aromas unappealing, prompting them to avoid areas where parsley thrives. Therefore, the presence of this aromatic in the garden helps to create a barrier, reducing the risks of potential damage caused by unwanted organisms. This also provides fresh material for parsley sauce if you prune judiciously with a pair of sharp scissors.
8. Chervil: With its delicate scent and subtle taste, chervil still plays a repellent role against harmful invertebrates. Its characteristic aromas act as a deterrent, discouraging slugs and other pests from approaching surrounding crops. Also, integrating it into the garden offers natural protection.
9. Comfrey: In addition to its fertilizing properties, comfrey has repellent effects on young leaf pilferers. The compounds present in comfrey create a barrier that deters these undesirables from approaching neighboring crops.
10. Cassis: Its leaves produce compounds that have a repellent effect on slugs. Planting blackcurrants near sensitive areas can help prevent attacks by these gastropods. As this slug déterrent also gives delicious fruit it is worth taking some time in their preparation. Blackcurrants prefer well-drained but moisture-retentive soil, although they will cope in most other soil conditions. They fruit best full sun, but will still do well in light shade. Avoid sites prone to cold winds or late frosts, which can damage the flowers and reduce the crop.
11. Marigolds: They have the ability to repel slugs while attracting beneficial insects, making them a strategic option for maintaining balance in the garden.

Each of these plants that slugs hate acts in a specific way, using volatile compounds or chemicals to create a natural barrier. Thus, we can repel these undesirables at a lower cost while preserving the health of surrounding crops. Note that it is also very interesting to prepare either a plant manure or a decoction with the species that we have just reviewed, to put an end to the devastation caused by slugs.

Slug attractant plants

In addition to the repellent plants that we have just discovered, we can use plant species that act in a different way since they attract slugs. You just need to install them at a good distance from the cannas that you want to protect from the attacks of these gastropods with their gargantuan appetite. Some of the best examples of attractive plants include:

1. Nasturtiums: Through their visual appeal, they function as a floral lure. If you want to divert the attention of gastropods in order to protect sensitive vegetables and plants, simply sow nasturtiums everywhere while respecting a sufficient distance from the crops to be preserved.
2. White clover: This plant also acts as a natural magnet, attracting unwanted invertebrates to a specific area where their presence can be better controlled.

By taking advantage of these plants, it is possible to minimize the potential damage caused by these particularly greedy gastropods while preserving the integrity of our cannas.

Physical barriers

First of all, the physical barriers which give good results. This simply consists of spreading crushed egg shells, wood ash, small-grained gravel or river sand around the canna pots and flower beds, in order to make it difficult for the attackers to move around.

Vaseline and Salt

As the underside of planter rims is a favourite hiding spot, smearing this area with a mixture of vaseline and salt will act as a repellent.

Coffee Grounds

Scientists have recently found caffeine to be highly toxic to snails and slugs. For use as a repellent, sprinkle used coffee grounds (full caffeine, not decaf) around the edge of flower and veggie beds.

Bait and trap

Next up are beer traps, which many gardeners say are a must-have. Since slugs are attracted to this drink, simply place shallow containers filled with this tempting beverage near the plants to be protected. The gastropods will not resist it and will drown in it after enjoying it. However, this process may not please everyone because it is still quite cruel… also it is not necessary to buy the best beers, as slugs are not at all fussy over the type ale they are quaffing.

Attract Natural Enemies of Slugs/Snails.

If a garden is rich in biodiversity, any slug or snail problem is nipped in the bud.

It is sometimes said that slugs (especially the Spanish slug) taste bitter and that for this reason, many animals won’t eat them. That is not correct. Slugs and snails have many natural predators. However, for various reasons, their enemies are disappearing in many areas, and this is one of the main reasons why slug populations are booming.

List of enemies of slugs & snails:

• • ground beetles
  • hedgehogs
  • marsh flies (Sciomyzidae)
  • centipedes
  • toads
  • newts
  • frogs
  • lizards
  • leopard slugs
  • Roman snails
  • blindworms
  • shrews
  • moles
  • harvestmen
  • songbirds
  • fireflies
  • snakes
  • opossums
  • and many more.

Help Predators of Slugs and Snails

These are some things you can do to help the natural predators of slugs and snails:

• • Offer as many indigenous plants and trees as possible.
  • Create wild corners in the garden and leave them alone.
  • Create garden ponds with rich bank planting.
  • Layer piles of stones with many cavities.
  • Build dry stone structures (dry stack stone walls) in sunny spots.
  • Pile up leaves in undisturbed, quiet, secluded spots.
  • Create blooming hedges with native plants or dead hedges.
  • Minimize garden lighting and where necessary use only warm-white LEDs.
  • Do not clean the beds in autumn and leave plant stems until spring.
  • Leave deadwood and use different varieties of coarse woody debris.
  • If possible, do not dig up the soil, only open the surface a little and loosen the subsoil.
  • Offer small open sandy areas with open water close by.
  • Mow the lawn rarely and insect-friendly (bee-friendly).
  • Refrain from using chemical crop protection.

These are things that everyone can do to create little arks for endangered species.  Some of them cause me problems, as they contradict things I have done all my gardening life, but I accept that they are the best sensible guidelines we can offer.

Hand-picking

Sometimes the influx has got so out of hand that the only answer is to wade in and kill them. A mix of water and salt can be used against them, as slugs and snails are easily defeated by salt. You can handpick them and throw them in a bucket full of salted water, or your can spray the mix onto them.

Conclusion

It is fundamental to do everything to maintain a balance in the ecosystem. This is why it is sensible to adopt sustainable approaches, as using natural methods to control pests of any type helps preserve the biodiversity and overall health of a garden. It is also more satisfying than systematically killing them with dangerous chemicals.