This article takes an in depth look at how best to prevent slug and snail damage in your vegetable garden.
Once you understand slugs and snails, it becomes much easier to keep their numbers down in your plot. Here are a few key snippets of information to take on board:
They need moisture: Damp soil means they can move around easily, dry soil means they are less active at surface level. If the winter is mild, they can remain active all year round.
They need shelter: Many will bury themselves in the soil, either to shelter from frost or to find moisture during drought. Other favourite shelters include hiding beneath objects like stones, watering cans, pots etc and in amongst weeds and foliage.
Some are more active beneath soil level (hence those slug-eaten potatoes) whilst others are more active above ground.
Many species will not bother your veg at all as they eat decaying material (and are great for the compost pile!)
Some species are more prone to feasting on vegetable plants and tend to choose vulnerable plants, which includes: older dying leaves, germinating or newly transplanted seedlings.
They do have some favourites in the veg patch, which include: pak choi, very young carrot tops and celery, lettuces and spinach
How to Keep Numbers Down
There are so many things that you can do, but what we’d really like to emphasise is that if you struggle with slugs and snails in your plot, the best thing to do is to take a multi-pronged approach. By doing so, you will find that your plants do much better and that slugs and snails become easier to stay on top of through the growing season.
Remove hiding places
Keep a tidy plot with minimal hiding places for slugs and snails to shelter in. This means removing ‘stuff’ like watering cans and empty pots, keeping on top of weeds and so on. The clearer your plot is, the fewer slugs and snails you will have to contend with – if you can remove the sides of raised beds, even better as this is an easy hiding place for them.
Water in the mornings
The idea behind this is to get watering done early in the day so that most of the water can soak into the soil before evaporating off. With the water soaking in quickly, roots can use the water during the day while the surface of the soil dries out again in the sun. By evening, the soil is drier meaning that slug and snail activity will be lower overnight.
Set beer traps
You can make a slug pub buy sinking small shallow containers (ramekin size) into the soil at intervals, and filling them with cheap lager. This attracts slugs and lures them away from your crops. It has a downside, in that it kills the slugs, but it is quite effective.
Build a citrus fruit shelter
Hollow out the flesh of grapefruits, and prop the shell up on a stick – this makes a convenient place for slugs and snails to hide during the day. At dusk, you can gather them up in a bucket and move them to somewhere like a compost heap or an overgrown patch where they will readily find food away from your crops.
Put barriers around plants
There are several ways to create barriers on the soil around the base of veg plants. Wool pellets are very good, especially if you are growing in a small raised bed as you can cover the whole thing quite easily (not ideal for larger plots). Many gardeners swear by crushed egg shells, or you can buy natural grit barriers. All these things are designed to make it unappealing and uncomfortable for slugs to cross the barrier in order to reach the plant.
Copper tape around pots
This is a good option for those who are growing in pots and containers – wrap the pots in copper tape (which you can easily buy from garden centres). The tape gives the slugs and snails a small electric shock and deters them. Used together with wool pellets around the stalk, this is an effective measure.
Keep plants healthy
Healthier plants can withstand slug damage much better. If you grow plants in good quality soil or compost, give them a liquid feed and some wormcast fertiliser, and keep them sheltered from strong wind and cold nights, you will find that they grow stronger and naturally resist (or even repel) slugs and snails.
Strip off dying leaves
Older, decaying leaves are really attractive to slugs and snails, so pull off those lower yellowing leaves of brassicas like kale, broccoli, sprouts and cabbages and any foliage that has fallen onto the soil. Likewise, the older, damaged leaves of plants like spinach, lettuces and chard can be removed. Add it all to the compost pile.
Other natural controls
You may find you have good results using nematodes. You can buy this natural control online from specialist suppliers. You will need to follow the instructions very precisely, but used correctly they can be quite an effective way of getting a slug problem in a larger plot to a more manageable size.
What About Slug Pellets?
There are basically two types of slug poison found in slug pellets. The first is Metaldehyde which is used in most non-organic pellets. The second is Ferric Phosphate, the type usually found in organic pellets.
Metaldehyde is a “low toxic” poison which makes the slugs swell up with water retention and then they die. Although it falls under the category of “low toxic” it is usually labelled as “harmful to pets & children” and all advice points to keeping it from getting into our drinking water as it is poisonous.
Ferric Phosphate, which tends to be ‘certified for organic use’, is basically an iron overdose that damages the slug’s digestive system and kills it. It is often purported to be harmless to children, pets and animals, although there is some contradictory advice out there.
Needless to say, we would not advise using slug pellets, but you are, of course, free to make up your mind and we would encourage you to do your own research before you decide to use them.