Slugs and snails have a tremendous capacity to frustrate gardeners. Overnight they can destroy young seedlings and disfigure your favourite plants. There are numerous ways to stop slugs and snails. The most common is the ubiquitous slug pellet; however, many gardeners are reluctant to use a poison which can harm wildlife and the environment. If you wish to avoid chemicals there are still many effective methods to control slugs, these are some of the most popular.
If you save an old plastic container and then sink it into the soil it can provide an excellent beer trap. Slugs are not fussy so feel free to use the cheapest beer. Also make sure it is easy for the slugs to slide into the container by keeping the edges close to the soil level. In the morning, you will find the beer trap full of drunk slugs. When it is full simply dig a whole and pour the contents in; then replace with fresh beer. I have used this method to great effect and it is completely environmentally friendly.
Slugs require a smooth surface to move. If they come across a barrier of grit and gravel they will not be able to pass. Therefore, you can protect your favourite plants and vegetables. This is a cheap way to protect the odd plant. However, it can be quite time consuming, unless you only have a small number of plants. Also if the barrier is not extensive, some slugs may be able to pass by.
Similar to eggs shells and grit copper strips can be placed around plant pots to prevent slugs climbing into them. The metal strips can be bought from local garden centres and once in place offer a permanent deterrent to slugs climbing in.
One of the best organic ways to decrease your slug population is through encouraging their natural predators. One of the best slug eaters is the humble frog. If you create a natural pond to encourage frogs and toads, you will find a natural ally in the fight against slugs. On a good night, frogs can get through 10-20 slugs so they can be very powerful.
Some birds, especially the Blackbird love to eat frogs. Encouraging birds into your garden with a bird table may help provide another predator for eating slugs. Unfortunately in the UK, the decline of the Song Thrush has been attributed to the use of slug pellets (the birds get poisoned on the slugs who have eaten pellets) This is another good reason for not using slug pellets.
If you go out in wet conditions, especially around dawn or dusk you may be able to find and kill a lot of slugs yourself. With a trowel you can easily slice them in half. To make your job leave a lettuce leaf around and check under stones.
If pursue these methods you will find the slug population drastically declines; it can also be quite good fun to encourage natural methods of dealing with slugs, rather than resorting to chemicals.