How To Get Rid of Slugs and Snails in the Garden

How to get rid of slugs and snails in the garden, is one of the most asked questions, especially by people gardening in wetter climates. They can cause huge amounts of damage as they eat up your plants.

Check the internet and you will find plenty of home remedies and DIY projects for getting rid of slugs and snails. The problem is that most of them either don’t work or have a limited effect on slugs. What does work?

Slug vs Snail

What is the difference between a slug and a snail and more importantly, are the treatments to get rid of them different?

Slugs and snails are the same class of creature called gastropods, part of the mollusk phylum. Most gastropods live in water but here we are taking about land slugs and snails. The obvious difference is that one has a shell and the other does not.

There are some other minor differences, but from the point of view of a gardener, they can be considered to be the same animal. Treatments that work on one, will work on the other. The effectiveness of any treatment does vary a bit depending on species. I’ll use the terms interchangeably in this post.

For a good introduction to this topic see the first part of this free, online book, Identifying Land Snails and Slugs in Canada.

Do You Really Have a Slug Problem?

Slugs and snails get a bad rap. Most people who find holes in leaves will blame them for the damage when in fact many other critters can produce the same type of damage. If you don’t see a slime trail on new damage, it is probably not a slug.

Take the time to get a proper ID. There is no point in treating for slugs if you don’t have a slug problem. This video gives you more detail: https://www.youtube.com/watch?v=W-ul631ut1s

Home Remedies for Slugs

I have discussed many home remedies on GardenMyths.com and therefore I will only summarize them here and provide links for a more detailed discussion.

The Latest Science

The latest testing found that bread dough and bread dough slurry were the best attractant for various species of slugs and snails. It was more effective than beer.

Beer for Slugs

Slugs are attracted to beer but it is really the yeast, not the beer, that entices them. The common method is to put out small dishes of beer and hope the slug drowns in them. You will catch some slugs, but most just come, get a drink, and leave happy.

Ammonia and Snails

Spraying ammonia on soil and plants to stop snails is useless because it evaporates before snails get to it. Besides too much ammonia can harm plants.

Spraying snails directly with a high dose will kill them. But do this only on the ground – not when they are on your plants. Who is going to go out at night and hunt for snails?

Eggshells Stop Slugs

People suggest putting crushed eggshells around plants to keep slugs away. It just does not work. Don’t believe me – watch this video: Eggshells Don’t Stop Slugs.

Coffee Grounds Stop Slugs

Cover the ground with coffee grounds and slugs stay away – that is the claim. They might not like coffee ground, but they have no trouble crawling over them. They don’t work.

Get Rid of Snails With Copper

There are two options here. Option one to surround plants or pots with copper tape. Snails don’t really like crawling on copper, but it does not prevent them from doing so if they want to get to your plants.

Some people suggest copper pennies, which is completely useless.

Copper wire will work if you connect the wire to a live battery. This may be an option on raised beds where you can surround the whole bed with the copper wire. It does not prevent slugs from burrowing under the sides of your raised bed.

For most garden situations, copper is not going to do very much to control slugs or snails.

Cornmeal Explodes Slugs

Put cornmeal on the soil and wait for the slugs to eat it. Once in their gut, it expands and the slug explodes. This advice is commonly found on the internet and it is baloney. No animal will be blown up if they eat cornmeal.

Slugs and Diatomaceous Earth

Diatonaceous earth does work to some extent. Slugs do not like crossing the dry material – I am not sure why. When diatomaceous earth (DE) gets wet, slugs no longer have a problem crossing it.

Here is the problem. To control slugs you spread DE on the soil to keep them away from plants. But soil is moist, and once the DE gets wet it no longer works until it dries out. At a minimum you need to reapply it every time it rains or you water. It also takes quite a bit to control a larger garden.

If you do use it, make sure you buy some that is labeled either as a pesticide, or for human consumption. The type used for filtering pools does not work on slugs.

Table Salt Kills Slugs

Table salt will kill them if you sprinkle some directly on the slug. Spreading salt on the soil is useless. Keep in mind that the sodium in salt is toxic to plants and it is best not to use it in the garden.

Slug Resistant Plants

One option is to buy slug resistant plants. For example, in the case of hostas, slugs will eat holes in some of the thinner leaves, but will leave the thicker cultivars alone. Ones with puckered leaves like Hosta sieboldiana, are less bothered by slugs.

Some plants are just slug magnets. Consider replacing them.

Attract Slug Predators

Snakes, toads, frogs and birds (blackbirds and thrushes, robins, starlings, rooks and crows, jays, ducks, sea gulls, owls and wild turkeys) love to eat slugs. By creating a good habitat for predators you let them take care of the problem for you.

Ground beetles also eat slug eggs and baby slugs. A good mulch encourages ground beetles to stay in the garden.

Water Less

Grow things on the dry side. Slugs and snails need a lot of water and if things dry out too much, they move on to a neighbor’s garden that gets watered more.

Hand Picking Works

Hand picking slugs and snails works, but I don’t think too many of us do this.

Water the area in late afternoon. Then hunt them a few hours after sunset using a light.  Dump any you find in soapy water to kill them.

Weeding after a rain or early in the morning when dew is still on plants, also works. If I find a snail, I just step on it and feed the birds.

Use Plants to Control Slugs

A trap crop is one which you grow that attracts slugs. Once slugs are on the plant you discard both the plant and the slugs. Or you can place traps and baits near these plants. If you plant enough of the trap crop you can leave it and it will keep slugs away from other less desirable plants. Some trap crops you can try include; green lettuce, cabbage, calendula, marigolds, comfrey leaves, zinnias and beans. Here is another list of slug magnets.

I am bit skeptical about the above list of trap crops – I am not convinced they have been tested to work.

There are statements on the internet that you can also use plants to repel slugs, such as; ginger, garlic, mint, chives, red lettuce, red cabbage, sage, sunflower, fennel, foxglove, mint, chicory & endive. While it is certainly true that slugs leave some plants alone, I am very suspicious that this list actually repels slugs. Note that cabbage is on both the trap crop list and the repellent list. A search of the literature found no studies that looked at this, but some plant extracts have been shown to work.

Nematodes Control Slugs

There are special nematodes that kill slugs and they are commercially available in Europe, but not North America, because they are not native here.

These nematodes are different than the ones used to control grubs in lawns.

As with any nematode, follow application procedures to the letter and make sure the pest is alive when you buy it.

Slug Pellets

Slug pellets containing an active ingredient that kills slugs and snails. The two common ingredients are metaldehyde and iron phosphate. Iron phosphate is claimed by many to be safer since it is a more natural chemical, but it might not be the best choice. For more on this have a look at this comparison; Slug Bait – Metaldehyde vs Iron Phosphate

Both of these molluscicides are effective and relatively safe, when used properly.

Sprinkle them on soil where you frequently see a problem. Don’t pile the pellets up, which makes them more attractive to pets and children and less effective for slugs. Timing is important since they are more effective in cool, damp weather when mollusks are active. It’s best to apply them in the late afternoon.

Wood Chip Mulch

How does a wood chip mulch affect slug populations? I have not found a clear answer to this question.

Wood chips help keep soil moist and cool, which favors the slugs. Some claim they don’t like crawling on wood chips, but I have found no research to confirm this.

The wet cool environment also increases the population of macroinvertebrates, including known slug predators such as carabid beetles.

Does the increase in predators outweigh the better slug environment? We don’t know, but one slug expert suggested to me that “wood chips would discourage slugs until they start to produce mushrooms, of which many slug species are very fond.”

Does Sanitation Control Slugs?

Many garden information sources say that sanitation will control slugs. Removing dead plant material, mulches, old wood, rocks and weeds will create drier conditions which in turn makes the habitat less desirable to slugs.

But then slugs prefer to eat rotting plant material over living mature plants, so if you remove their favorite food any remaining slugs will need to eat your plants. Removing mulch also decreases the number of slug predators and requires more irrigation which encourages slugs.

I don’t know the correct answer to this question, but leaving old vegetation and mulch has many other benefits for your garden. Unless you have a very serious slug problem it is probably better to leave them in the garden.

This may also be a case where the use of a few chemicals to rid slugs is warranted?

The Bottom Line

Most gardeners do not have huge slug problems. Learning to live with some holes in leaves goes a long way to solving the problem.

No one single method will remove all slugs from the garden. Consider using more than one method for better control and unless your neighbors do the same, any control will be temporary.