Slugs and, in a lesser evil, snails are considered a nightmare by many gardeners: they are slimy, strange looking, and emerge in the dark of night to devour newly planted seedlings, very tender leaves and ravaging your young shoots.
Because slugs are nocturnal, it can be hard to pinpoint them as the culprit when garden damage is discovered, but once the mystery is solved, growers often turn to poisonous traps or baits to deal with these unusual creatures.
I invite you to reconsider. Slugs are actually fascinating, gentle animals, and are also an important food source for other creatures that are beneficial to a garden ecosystem. While poisons do work, there are many other methods to getting rid of slugs in the garden while preserving biodiversity in your garden.
In this post, we will explore the numerous slug and snails control tips for dealing with garden slugs, including garden management, slug deterrents, humane trapping, encouraging slug predators, and, if necessary, poisonous traps and baits.
But before we dig into that, let’s get to know slugs and their life cycle, and understand how to recognize them and their damage in the garden.
What Are Slugs?
Slugs are a common garden pest that can damage established plants and destroy seedlings overnight.
While they may frustrate gardeners and devastate crops if left unchecked, beyond these negatives, slugs are captivating creatures.
Let’s take a moment to understand and appreciate them–and then discuss how to get them out of the garden.
A common misperception is that slugs are a kind of insect or worm, but neither is true. Slugs are actually a soft-bodied, land-living mollusk, which makes them related to clams, mussels, scallops, octopi, and squid.
Slugs are also closely related to snails, and all of the strategies outlined here to combat slugs in the garden will work on snails, too.
Slugs are hermaphroditic. This means that each individual slug possesses both male and female sex organs, so every slug has the power to lay eggs (that’s good news for slugs, bad news for gardeners). Slugs mate with each other, but self-fertilization is possible.
Slugs are also nocturnal creatures. They feed and are active at night and disappear during the day, which can make it difficult to pinpoint when slugs are the cause of garden damage, unless you know what clues to look for.
Slugs have an important role to play in the food chain, as well. They provide sustenance for many creatures–birds, insects, reptiles, and amphibians, and a few mammals–many of which are good for the garden.
The complete removal of slugs would upset this careful balance, so the goal doesn’t need to be total eradication, but relocation or reduction of the population–enough that you can garden in peace.
The Slug Life Cycle
The average lifespan of a garden slug is one to two years. They are able to survive cold winters by burrowing underground.
Slugs can lay up to 300 eggs per year, typically in clutches of 10-50 eggs, depending on the species.
The time it takes for a slug to reach reproductive age varies by species, but most garden slugs mature in 5-6 months.
Slugs hatched in the spring will mature over the summer and lay eggs in the fall, which will hatch in the spring.
However, slugs can lay eggs any time of year if the conditions are right, and the time it takes for eggs to hatch is determined by the temperature and moisture levels in the environment.
Should the weather become too cold or dry for the eggs before they hatch, they can remain dormant for years until conditions improve.
Because slugs lay eggs throughout the year, there may be overlapping generations of slugs, and slugs of all life stages, in the garden at any time.
How to Identify Slug or Snail Damage On Plants
Slugs are typically brown, grey, or orangish in color, and most are between 1-3 inches long.
They can be found during the day hiding out in moist, protected areas of the garden, such as in wood chip piles.
During the night, when they are active, they can be found openly feeding in the garden.
Because slugs are only active at night, learning to correctly identify slug damage through clues that are available during the day is key.
Slug damage is often mistaken for insect damage, leading gardeners to apply insecticides and other strategies that are ineffective against slugs, and potentially damaging to beneficial insects.
Slugs tend to target certain plants, so look for evidence of their presence on and around some of their favorite foods: tender lettuces, seedlings, cabbages, kale, strawberries, and hostas.
Here are four signs of slug damage to look out for:
1: The Mucus Trail
If you suspect slugs in the garden, a telltale sign to look for is the slimy, shiny mucus trail they leave in their wake.
This mucus trail is what helps them move, so you’ll find it wherever they’ve been, if you look carefully and it hasn’t been disturbed:
on the soil surface, the leaves of plants, and any object in the garden. Morning is the best time to look for a mucus trail.
2: Round, Irregular Holes
Slug damage itself is very specific. Because slugs have thousands of grater-like teeth, when they eat, they leave round holes with irregular edges.
These holes can be in the middle or edge of leaves, or even on fruits such as strawberries or tomatoes.
3: Disappearing Seedlings
Young seedlings are particularly vulnerable to slugs, because a slug (or several) can devour an entire seedling in one night.
If your seedlings disappear, or if the leaves are gone and nothing but the stem and midribs remain, this is indicative of slug damage.
4: Underground Damage
Slugs spend a great deal of time underground, where they can cause damage to root systems, tubers, and seeds.
If a significant amount of your seeds fail to germinate, or your potatoes are chewed up, slugs may be the cause.
4 Ways to Get Rid of Slugs in Your Garden Naturally
If you’ve identified slugs (or slug damage) in your garden, then it’s time to act.
There are five main strategies for dealing with slugs in the garden: preventative garden management, slug deterrents, trapping, encouraging predators, and killing slugs.
Let’s look at each strategy in detail.
Garden Management to Prevent Slug Infestations
If slugs don’t find your garden appealing, they will go elsewhere to live and reproduce. Try the following methods to prevent slugs from setting up shop in your garden:
1: Use Fine Mulch
Slugs love burrowing under bulky mulches like large wood chips, hay, and straw. These mulches create a moist environment with lots of protected places to hide, sleep, and lay eggs.
Switching over to a fine mulch such as finely shredded bark, compost, or leaf mold will discourage slugs. Oak leaf mold is particularly effective because oak leaves are thought to repel slugs.
2: Keep Your Garden Tidy
Slugs love moist, dark hiding places: under wooden boards, under cardboard used to sheet mulch, or log piles.
Eliminating these hiding places by keeping your garden tidy and clean will help discourage slugs from spending time there.
3: Plant a Diversity of Crops
Slugs prefer a buffet of their favorite foods, and one study of slug behavior noted that slugs ate 40 percent less in an environment with a wide diversity of plants.
Apparently, they did not enjoy having to constantly switch their diet. Having a wide range of crops in a small area may discourage them in your garden, too.
4: Encourage Worms in Your Garden
The same study found that the presence of worms decreased slug damage by 60 percent, possibly because the worms helped plants protect themselves from slugs by increasing the amount of nitrogen containing toxins in their leaves. Regardless, an abundance of worms in your garden is a good thing.
You can create your own vermiculture bin and regularly add worms from the bin to your soil, but good garden practices such as creating healthy soil with significant amounts of organic matter will attract worms to your garden, too.
5: Convert to a Drip Irrigation System
Drip irrigation precisely targets plants and their root systems. A drip system will reduce overall moisture in your garden while still sufficiently watering your plants, making your beds less hospitable to moisture-loving slugs.
In addition, drip irrigation is far more efficient and will save both time and water compared to manual overhead watering.
Even if you don’t switch over to a drip irrigation system, taking care not to overwater will help prevent a slug infestation by reducing wet areas.
Just make sure not to go too far by underwatering your garden instead.
6: Water in the Morning
Regardless of the watering system you use, water in the morning. This will give excess moisture in your garden an opportunity to dry out by nightfall, again making your garden less of a desirable habitat for slugs.
8 Ways To Stop Slugs And Snails Eating Your Vegetable Garden Naturally
Beyond some basic changes in garden management, there are a number of ways to make your garden less enticing to slugs, and make your plants harder to reach. The following methods will stop slugs and snails from eating your plants:
1: Use Garden Cloches As A Protection Against Snails And Slugs
Cloches are a great way to protect seedlings from being devoured by slugs. Cloches are small, inverted containers made of glass or plastic that protect seedlings from pests, including snails and slugs.
Inexpensive plastic cloches can be purchased online or at your local garden center. It’s also easy to make your own:
Use an empty water bottle, milk jug, or similar container. Cut the bottom off the container and place your DIY cloche over your seedling.
Be sure to remove the cap of the container; this vents the cloche, allowing excess heat to escape.
2: Use Cardboard Collar To Protect Your Plants
To protect larger plants from slugs and snails that won’t fit under a cloche, use a cardboard collar instead. Simply take a piece of cardboard about 6-8 inches high, bend it into a circle or square that fits around the base of your plant, and attach the edges.
Press the collar an inch or two into the soil to secure it in place. The collar will make it more difficult for a slug to reach your plants.
3: Use Sheep’s Wool Pellets Against Slugs and Snails
Wool pellets (sold under the brand name “Slug Gone”), are another effective barrier against garden slugs. The pellets are made from 100% waste wool condensed into a pellet form.
To use, simply arrange the pellets around the base of the plants you want to protect, then water in.
The water will cause the pellets to expand and felt together into a layer of wool that slugs will not want to cross.
Their skin will be irritated by the scratchy texture of the fibers, and the wool itself will draw precious moisture from their bodies.
4: Make Slug And Snail Barrier With Copper Tape
When slugs touch copper, they experience a slight electrical shock. In most instances, this shock is enough to get them to turn around–away from your plants.
You can apply copper tape in a border on the soil around specific plants. It’s also effective when attached to the edge of a raised bed, where it will protect the entire bed.
5: Install Miniature Electric Fence
In the same way as copper tape, a miniature “electric fence” around your raised bed will stop slugs in their tracks.
You can make an electric fence to deter slugs with lengths of galvanized steel wire (18 to 22 gauge) and a single 9 volt battery and battery connector.
Staple the wire around the length of the outer sides of your raised beds, using two lengths of parallel wire spaced ¾” apart.
Attach to the connector and battering, enclosing both in a plastic box in order to protect them from the elements. The 9 volt battery will be intense enough to discourage slugs but not kill them.
6: Apply Diatomaceous Earth
Diatomaceous earth (DE), when sprinkled in a thin but solid layer on the soil, will slow down and discourage slugs, but it’s not the most reliable method for deterring them (it’s also a myth that it kills them).
DE does kill insects, both pests and pollinators, so if you do choose to use it, it’s best to apply it in the evening, when bees aren’t active, or to avoid it entirely during the flowering stage.
Although DE isn’t the most effective slug deterrent, it does have some effect, and you may already have some on hand from other projects.
7: Keep Slugs Away With Repellent Plants
They also dislike plants with fuzzy or furry foliage such as geraniums. Plant these in your garden, near slugs’ favorite foods if possible, to ward off slugs.
8: Create a Slug Garden
This method is more of a distraction than a deterrent, but it is still effective. Keep slugs and snails out of your garden by attracting them to a space away from the vegetable garden that they will love even more.
This is an area that you can sacrifice to the slugs, allowing them free reign, or you can choose to use this area as a trap, making it easier to relocate or kill the slugs.
To make a slug garden, create a space that is well-watered and moist, with the kinds of mulches they favor (large wood chips, hay, straw), and that contain their preferred crops, such as tender lettuces. You can also add logs, planks of wood, and other places for them to hide.
How to Humanely Collect or Trap Slugs
While good garden management and deterrents are effective, if you have a large slug infestation in your garden and are seeing a lot of slug damage, you may want to take your efforts a step further and decrease the slug population by collecting or trapping them. Be sure to wear gloves when handling slugs as they can carry pathogens.
Once you’ve gathered a large number of slugs, you can relocate them somewhere far from your garden.
You don’t need to drive them anywhere; research has shown that a relocation of just 65 feet is far enough away to prevent slugs from returning to your garden.
Or, if you choose to, you can kill the slugs by placing them in a bucket of hot soapy water (the water must be hot for this to work).
If you have poultry, your birds will enjoy slugs as a nutritious treat, but don’t feed them too many at once. Slugs carry parasites such as roundworm and gapeworm that can make your flock ill.
Collecting slugs by hand is the easiest, most direct way to cut down the slug population in your garden. After night has fallen, grab a headlamp or flashlight and a bucket and head out to the garden.
You’ll be able to see the slugs in action, wreaking havoc on your garden, and easily pick them right off your plants.
While slugs are nocturnal, you don’t have to be a night owl to catch them. If you don’t want to stay up late to collect them by hand, you can make a trap instead: an irresistible place for them to rest during the day, where you can collect them with ease.
Unlike some slug traps, these methods are humane and will not kill the slugs. Dig a small hole (about 6” deep and wide) and cover the hole with a board.
Or, simply lay a large board or thick sheet of damp cardboard directly on the ground. Slugs will be attracted to these areas as a great place to rest during the day, at which point you can turn over the boards, scrape the slugs into a bucket, and relocate.
Encourage Slug Predators in the Garden
As mentioned earlier, slugs hold a vital place in the food chain. You can naturally lower the slug population by encouraging the presence of slug predators, many of which are beneficial to your garden.
Here are some common slug predators and how to encourage their presence in your garden:
1: Amphibians and Reptiles
Snakes, frogs, toads, and salamanders–all these creatures and more will prey on slugs. They love to hunker down in the same moist, sheltered environments that attract slugs:
under thick mulches, old boards, and mossy logs. An added benefit to humane slug traps or a dedicated slug garden is that these spaces will also attract their predators.
2: Ground Beetles
There are over 2,000 species of ground beetle. Like slugs, ground beetles are active at night and prey on many pests–especially slugs!
You can encourage the presence of ground beetles in your garden by building a “beetle bank,” an ideal habitat for them.
Ground beetles love raised, grassy areas where they can escape from moisture and enjoy protection from the tall grass.
Create a beetle bank by making a berm or mound of soil about 18” high and two to four feet wide.
Plant with several species of native bunchgrass and continue to water until the grasses are established.
An added benefit is that the bank will attract and house other beneficial insect species, too!
Birds will feast on young slugs, which are often prevalent in early spring. Attract birds to your garden during this time of year with bird feeders, suet cakes, and birdbaths.
Nematodes are microscopic worms naturally found in soil, but you can easily increase their population.
Nematodes are available online or at your local garden center, and can simply be mixed with water and added to your soil.
For best results, dose your garden with nematodes three consecutive times (spring/fall/spring or fall/spring/fall) and then follow up with one more application 18 months later.
Nematodes don’t eat slugs directly, but instead kill and feed off of their eggs. You may not find a significant difference in the slug population during the first year of nematode application, but expect to see a big drop in the second year.
Firefly larvae feast on slugs, snails, and worms. Refraining from the use of insecticides in your garden will support the firefly population, along with that of other beneficial insects. Fireflies are also attracted to tall grasses, water features, and wood piles.
How to Kill Garden Slugs And Snails
Finally, let’s discuss methods for killing slugs. If all else fails, you may need to resort to these trapping or poisoning methods in order to save your garden.
1: Use Beer As A Slug Trap
Slugs are attracted to the yeast in beer, so beer traps are an effective method against them. They will crawl into the trap and drown, or be killed by the ethanol in the beer.
To make a beer trap, all you need is a small container (like a plastic cup) and a cheap beer. Bury the cup in the soil until the rim is just above soil level, and fill with several inches of beer.
These traps will quickly become a disgusting mess of beer and dead snails, so be sure to refresh the traps every day or so until the infestation is under control.
Note: You may have heard that cornmeal traps will also kill slugs, due to the cornmeal rapidly expanding inside their bodies and causing their stomachs to explode.
This is a myth, and cornmeal traps are not an effective treatment for slugs. So stick to the beer!
2: Iron Phosphate Pellets
Iron phosphate pellets, sold under the brand name “Sluggo,” will kill and control snails and slugs. Sprinkle a teaspoon of Sluggo bait over one square yard of ground around the plants you’d like to protect.
After ingesting the pellets, slugs will stop feeding and die within 3-6 days. Sluggo is working even if you don’t see dead slugs; slugs will usually retreat to a dark, secluded area to die.
Iron phosphate is a naturally occurring substance, and any uneaten pellets will break down and be absorbed by the soil.
Sluggo is approved for use in organic agriculture and is considered safe to use. But even organic farmers have restrictions on how they can use Sluggo.
They must be using other, non-chemical methods to reduce and discourage slugs and decrease the need for bait before applying Sluggo.
It’s best to emulate these organic farmers and use Sluggo after you’ve employed other methods.
Sluggo isn’t without risk. It can sicken mammals, such as dogs, who cannot excrete the extra iron ingested from Sluggo.
However, if you follow the application directions, using only a small amount and spreading it thoroughly, a dog is unlikely to be able to eat enough Sluggo to get sick.
If you do use Sluggo, make sure to use the original Sluggo product, instead of newer variations such as Sluggo Plus or Iron Fist.
The original Sluggo contains one active ingredient: iron phosphate. Later products such as Sluggo Plus contain spinosad, a toxin that kills many insects including the roving beetle, which helps control snails and slugs.
Some slug poisons also contain sodium ferric EDTA, a chemical which drastically reduces the earthworm population and has increased risk to pets and other mammals.
3: Poisons to Avoid
Avoid any slug poisons that contain either metaldehyde or methiocarb. These ingredients are both toxic to mammals, even in small amounts, and are not safe for pets.
Ammonia or alcohol sprays are sometimes recommended as slug poisons, but these sprays also risk burning your plants and harming insects that come into contact with them.
Since sprays also require direct contact with slugs, they aren’t any easier than collection or trapping methods, so there’s really no advantage to them.
Slug Deterrent Methods That Are Myths?
Two common myths about slugs is that they can be discouraged by coffee grounds or ground eggshells. Neither of these is an effective slug deterrent, so save them both for the compost pile.
As you can see, even though slugs can cause quite a bit of damage in the garden, there are a multitude of ways to deal with them effectively–and humanely, if you prefer.
By employing any or several of the strategies outlined above, your garden will be protected from slugs and you’ll be enjoying an unblemished harvest once again.
Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.