Dealing with Slugs and Snails

Did you know? If all the offspring survived of one grey slug they would have 90,000 grandchildren and and 27,000,000 great grandchildren.

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Know your enemy, says the proverb, and it’s top advice for dealing with slugs and snails, the dreaded garden pests.

At this time of year, these molluscs are a menace. They devour young, tender leaves, casually munching the plants we so lovingly nurture. No wonder they head the gardeners’ black list.

To limit the damage, first get to know your enemy. All too often, slugs and snails are sadly misunderstood. There are dozens of slug species. Most are entirely harmless. They lead a gentle, quiet life, slowly breaking down garden waste. Some burrow underground, others nest in nooks and crannies.

With slugs, size matters - the small ones are often the nastiest. The gray field slug (Deroceras reticulatum), a mere three or four centimeters long, does serious damage. The common garden slug (Arion hortensis) is just as bad, a touch bigger and blackish gray in colour.

Snails, of course, are basically slugs with a shell. The common garden snail (Helix aspersa) lives longer than slugs, around seven years compared to one, and boats around 15,000 teeth.

Both slugs and snails are hermaphrodites, although two specimens are needed to reproduce. Snails writhe for hours in slimy bliss, with some species firing love darts at their mates.

They come out at night, or after rain. Both slugs and snails find it easier to get around when soil is wet – a good reason to water your plants in the morning, so they’re dry late at night.

To hunt the pests, grab a torch and a bucket to nab them at the scene of the crime. Next, find their hiding places. Peer under pots and containers on a balcony. Lift up the lid of your compost bin. Root around in piles of logs, bricks or other rubbish.

To dispose of them, first examine your conscience. Some people are happy to crunch underfoot or chop in half; others are more squeamish. You can drop them in salty water, taking care to not then pour out over the soil.  For the tender-hearted, liberate elsewhere.

For a more long term approach, try to reduce their potential hiding places. Move your compost bin away from your veg patch. Keep pots and containers away from cracked walls or bushes, where they live. Seal up nooks and crannies in raised beds.

To protect vulnerable plants, cover with a plastic water bottle with the bottom cut off – a simple recycled cloche. Old net curtain, strung over supports, is another frugal method.

I’m a big fan of ‘slug pubs’ – a jar or yoghurt pot dug into the soil and filled with lager. The yeast attracts the slugs. Be careful to raise them half an inch or so above the soil surface, to stop other creatures falling in. Replace the booze every three days.
Or you can use the skin of half a grapefruit to attract and gather the slugs and snails.

The posh option is nematodes, microscopic worms which kill off the slugs. They occur naturally in soil, but you buy them in large doses to mix with water and sprinkle. (defenders.co.uk or greengardener.co.uk).

The drawback is price – you need doses around every six weeks, for about a tenner a time. And be aware that the soil must be warmer than 5°C/40°F for the treatment to work.

At all costs, avoid slug pellets. Some people sprinkle them round the garden like salt over chips. But it’s a toxic solution, which affects other harmless wildlife.