Organic Slug & Snail Control

By Andy McIndoe

Here's my top tips for controlling slugs and snails organically

Traditional slug pellets contain metaldehyde which is harmful to wildlife. Birds, amphibians and mammals are unlikely to eat the pellets, however they will eat slug and snail corpses and that’s where the real harm is caused.

So what are the top 10 alternative natural remedies?

Join my Gardening for Wildlife course to learn more about encouraging and discouraging wildlife in your garden.

Slug & Snail control history

There is no doubt that slugs and snails are the gardener’s worst enemy in many parts of the world. These voracious slimy creatures are able to devour several times their own body weight of your favourite plants in just one meal.

They seem to appear from nowhere when the weather is mild and damp. Overnight they appear from neighbouring vegetation, under stones, under the rims of plant pots, a thousand hiding places.

It is therefore no wonder that so many different ways to attempt to control them have evolved over the years.

Fifty years ago most gardeners kept a drum of table salt at the ready to pour on to the offending creatures as they appeared. Salt was sprinkled around newly planted seedlings.

Of course it dissolved instantly causing potential harm to soil and other wildlife. If you live near the coast you may well use seaweed around the garden which many claim is an effective barrier.

Wood ash may be deterrent for a while. Like many “natural” remedies, it seems to work in some gardens and is totally ineffective in others. Some slugs seem to be deterred by coarse grit spread around plants. Other slugs and snails cross intrepidly. Maybe it’s a bit like walking over hot coals.

Of course the ideal method of natural slug and snail control is to encourage enough natural predators to inhabit your garden: frogs, birds, hedgehogs and the like. This can only be successful if your other slug control methods are harmless to them. (Join my Gardening for Wildlife course for more on this).

So here's my tried and tested top 10 ways to naturally control slugs and snails:

1. Coffee Grounds.

Coffee grounds spread around plants you want to protect do deter slugs and snails.

Some swear by this method and coffee grounds are not a resource we are short of considering the number of coffee shops that have sprung up everywhere in the past quarter of a century.

No good for those of you using pods in your espresso machines; but ideal for those still using cafeterias.

2. Beer Trap

Organic Slugs & Snails Control

Slugs love beer, apparently. A container such as a margarine tub or large yogurt pot sunk into the ground so the rim is at or just above soil level, filled with beer acts as a slug trap.

The slugs are attracted, fall in and drown; a great way to go. What of those that don’t like beer? They are still eating your lettuces.

3. Eggs shells and sea shells.

Organic Slugs & Snails Control

These are effective for a while when spread in a barrier ring around precious plants. If you live by the coast, near a sandy beach with bivalves you may have access to sea shells.

If using egg shells you will need to eat a lot of eggs to keep the average plot slug free.

4. Diatomaceous earth (DE).

Organic Slugs & Snails Control

This is an interesting one and popular in some parts of the world. Diatomaceous earth is the finely ground fossil remains of freshwater prehistoric diatoms.

It is used in various grades to kill bedbugs, cockroaches and food grade DE is used to kill internal parasites. As an abrasive powder inhalation is to be avoided.

Slugs can’t cross it but it does need to be replaced after rain; no good to me I fear. Some say perlite works in the same way: worth a go.

5. Copper tape.

Organic Slugs & Snails Control

Slugs can’t cross copper, so copper tape acts as a barrier. You can use a ring of it around an individual plant, however it works best to protect plants in pots.

A ring around the pot, just below the rim prevents the slug from getting at the plant in the pot. There are copper impregnated mats too that you can stand pots on.

These are successful until the plant grows; its leaves touch a neighbouring plant and the slugs and snails use it as a bridge.

6. Slug repellent plants/Slug attractive plants.

Organic Slugs & Snails Control

Garlic, Lawn Chamomile, chives. Some plants repel most slugs and snails and these may have a deterrent effect when planted alongside or used to make an extract.

Many gardeners swear by garlic as a natural pest control. Some say chives are effective it the leaves are tied around vulnerable plants; sounds fiddly.

You can of course plant something that is more attractive to slugs and snails. Lawn chamomile seedlings are reputed to be irresistible.

The slugs go for them and you wait in ambush, pop them in a jar and deport them.

7. Recycled wool waste pellets.

Organic Slugs & Snails Control

Shoddy, wool waste is a by-product of the wool manufacturing process. This is turned into pellets that you spread around the plants as a barrier.

They swell up and reveal nasty little fibres that are irritant to slugs. Over a period of time the pellets degrade and act as a plant food. I’ve used this one and it is effective when protecting newly planted seedlings and emerging perennials.

8. Nematodes.

Organic Slugs & Snails Control

Biological control of slugs and snails is effective in small gardens if carried out with care early in the season. Basically you water on a solution of nematodes (microscopic worm).

These penetrate the slug, infect it and kill it: not a pleasant thought but organic and effective. You usually buy from mail order and storage and usage instructions must be followed if it is going to work.

9. Wheat bran/Corn Bran.

Organic Slugs & Snails Control

Small piles or rings of wheat bran or corn bran are eaten by slugs and snails and they cause desiccation and death. Totally organic and if wildlife eat the corpses they are getting extra nutrition.

This method has had great following. Disadvantage: you need to replenish regularly in rainy weather. Advantage: buy it from the health food store.

10. Nature Friendly Slug Pellets.

Organic Slugs & Snails Control

Organic Slug Pellets are based on Iron phosphate rather than metaldehyde. If you want an off-the-shelf, easy solution that is simple to use, these are probably your best bet.

They are approved for use in organic gardening and have soil association endorsement. Use sparingly: not like granular fertiliser.

They are not completely non toxic to other animals.  They can kill earthworks and there have been some reports of dogs becoming ill after ingestion them. But they are still a safer alternative to metaldehyde.

See Upon Further Review…Iron Phosphate for Slugs and Snails

There are so many more possibilities, and I know you will have your suggestions: please post them below. Let’s keep to the passive solutions like these: no violence. However, I do understand why gardeners get so emotional about slug and snail damage.

If you try or have tried any of these do let us know what you think.

For more advice on gardening for wildlife join my classroom: Gardening for Wildlife or join the RHS Level 2 course for a formal gardening qualification.

Recommended course

Gardening for Wildlife taught by Andy McIndoe

Gardening for wildlife teaches you how to create a garden to attract birds, bees, insects and small wild animals.

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