If you have a garden, then your worst enemies are the snails and the slugs. You’ve had tried n number of ways to control them, but none of your slug/snail control measures worked to 100% satisfaction.
That was because you never bothered finding out the species of slug you were dealing with. Of the most damaging varieties, the gray garden slug, the banded slug, the tawny slug and the greenhouse slug are infamous. But what makes snail/ slug control all the more difficult is their capacity to reproduce; both the types being hermaphrodites, all have the potential for laying eggs. Therefore, to embark upon an effective snail control measure, you need to know their behaviors.
Snails and slugs prefer being out at nights and in a cloudy/foggy weather. They avoid sunny days, heat and bright light. In cold weather, they hibernate in the surface soil, sealed within a membrane they produce.
There is nothing called an effective snail and slug control method; in fact, what you need to do is combine a number of different methods to bring forth a satisfactory outcome. So here we go:

- Eliminate the hideouts, especially on a warm, sunny day. Turn every board, stone, garbage heap, areas with thick shrubs and areas around tree trunks. Reducing the hiding places shall welcome fewer snails or slugs and shall make survival tough for them.
- Reduce the number of humid/moist areas. This shall make the place a less-preferred habitat for both snails and slugs; top it up with plants (e.g. begonias, geraniums, Californian poppy, nasturtiums, lavender and rosemary) these nuisances just abhor. In case you cannot do that, put copper barriers around plants that they consider the most delightful treats (e.g. basil, cabbage, beans, dahlia, lettuce, strawberries and marigolds). Besides, you may also use woody plants and grasses of ornamental varieties to limit damages inflicted by snails and slugs.
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Slug Control
However, if there are not too many swarming your grounds, then handpicking can be opted for as an effective snail/slug control measure. But this pest control measure requires to be done on a regular basis; first, it should be carried out on a daily basis and then, weekly. They must be then put in soap- / household ammonia solution (5 to 10%) and then to be disposed off. Else, apply Bordeaux (copper sulfate and hydrated lime) mixture on tree trunks to keep them off. This is a pest control method requiring less hassle; once a year proves to be sufficient. But for that, you need to add a commercial spreader (white latex paint is also recommended as an alternative) to make the Bordeaux mixture persistent for long.