Slugs and Snails
Introduction
The most frequently asked questions concerning slugs and snails in a gardening context are 'How do I get rid of them?' or 'How do I stop them from eating my plants?'
There are a few different ways of dealing with them but it helps if we understand their environment.
Slugs & snails prefer to live in damp, shady places, among plants, plant debris and humus; crawling into crevices or beneath stones, pots, plastic etc... during the cold winter, or sunny daytime.
Only snails hibernate, sealing themselves within their shells. Slugs are more cold hardy & remain active in all but freezing weather.
Severe weather will dramatically reduce their number as will a long hot spell, as they lose moisture rapidly in dry heat.
They may feed several yards away and food is located by smell.
It has been found in trials that when damage becomes noticeable numbers can be 50/60 per square meter and can increase to 100/200 during warm damp conditions.
Bare hoed beds or deep beds - pros and cons
Well rotted organic materials are less attractive to slugs than fresh materials & so are preferable for mulching.
Mulches attract slugs with food and shelter and they also shelter many slug predators.
Bare beds make their lives hazardous if they are regularly hoed.
Barriers are easier to use on bare beds, but not impossible on deep mulch beds.
Most methods work with either, though handpicking is quicker on bare beds.
Natural predation is easier to encourage in deep mulch beds.
To overcome the disadvantage of mulches, plants need to be well grown, and perhaps planted out later, when larger and hardier.
Tips
Slugs & snails are attracted to tender young growth. They are usually less interested in hardier plants.
Try to grow in an open sunny site.
Try to reduce the use of cloches as these can harbour slugs and snails.
Use slow release fertilisers.
Water with care, too much can cause permanent dampness that can encourage slugs and snails.
Transplanted plants should be very thoroughly hardened off before planting out. Try to provide a physical barrier until the plants get hardier.
Maintain good crop rotation, organic addition, etc.
Do not grow susceptible plants.
Try to grow crops when the slugs are less active for instance grow Spring Cabbage, Broad beans, Garlic, shallots, overwintered onion sets, Welsh onions, sown early or even over-wintered for early crops
Collection Methods-
To help with finding slugs and snails, create hiding places. Strategically place upturned pots, tiles or slates around garden, propped up by a small stone make ideal hiding places for them during the day. Check regularly, collect the slugs/snails and dispose of in your favourite way. They will also take up residence on the underside of plastic bags or sheeting placed out on the ground. Simply lift the cover and dispose of them. If you don't like the feel of slugs use a hand trowel to pick them up.
Hunt at night, after a rain shower, during damp misty weather or after watering or overhead irrigation. Slugs & snails are especially active 2 to 3 hours after sunset. They are inactive during very cold or very dry weather and dislike heavy rain or wind.
Handpicking can greatly reduce slug & snail numbers locally & temporarily, so crops can survive & flourish. They travel only short distances & are strongly habituated to their locality. They only recolonise an area slowly - though many eggs may also hatch.
Different methods of getting rid of slugs and snails
Deterrents
When snails and slugs travel they lay down a layer of slime, which protects their foot. Loose particles in a barrier create a situation where the slug/snail loses its 'surefootedness' causing the slime track to lift up as it goes making travel difficult. It then heads for firmer pastures. Of course some of these substances have other effects too such as drying the slug/snail out. Various deterrents include:
Crushed eggshells
Break up eggshells and place around favourite plants. The slugs and snails do not like the sharp edges and move away.
Wood ash and soot
Wood ash or soot is said to deter them if scattered around the plants.
Coarse sand/Gravel
Use the sharp edged (something like flint) gravel, scattered around the plants.
Sawdust
Any will do but cedar is recommended.
Garden lime
Watch pH of soil. (If you have alkaline soils, adding lime isn't a good idea.)
Copper
Copper is said to cause electrical shocks in slugs and snails.
Place strips, 10 cm/4 inches wide around favourite plants. Very expensive and only feasible for a very few plants. Slugs/snails supposedly get an electric shock when their 'foot' touches the metal and they can't cross the barriers. (Click here for more details about copper barriers)
Epsom salts
Sprinkle lightly on the ground. Beware that a little Epsom salts will probably do no harm but used to excess will cause problems in the soil.
Bran
Sprinkled around plants, bran will deter slugs and snails. It will need replacing every so often, especially after a few heavy rain showers.
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© copyright 1999, P. A. Owen
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