11 Natural Ways to Deter Garden Slugs
Slugs aren’t picky about what they eat and come out to feed at night, making them difficult to control. Organic farmer Jenna Rich has 11 natural ways to deter garden slugs so you can return to the fun gardening stuff.
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Slugs might just be the most obnoxious garden pest there is. They’re slow-moving, so many of us think of them as harmless, but while we sleep, they cause irreversible damage to our young transplants and gorgeous hostas, causing us to feel helpless against these tiny creatures.
The good news is that there are many natural ways to deter garden slugs for free or inexpensively. In this article, I’ll discuss 11 natural ways to prevent garden slugs.
Diatomaceous Earth
Mollusks have slimy bodies, so they must be careful about substances that dry them out. Drying out can cause severe digestion issues, movement imbalances, and death. While Diatomaceous Earth (DE) doesn’t kill slugs, it positively deters them from the area and may cause them to think twice about returning.
DE is a natural, non-toxic powder made from crushed shells and fossilized algae. The effective ingredient is silica. Wear protective goggles and sprinkle the powder at the base of plants or the perimeter of gardens, being careful not to breathe any in. Reapply after rainfall and when you notice it has begun to break down. You can also mix it with water to create a spray for the undersides of leaves.
Pro Tip: Diatomaceous Earth also helps deter aphids and flea beetles, so keep it on hand.
Companion Planting
Companion planting proves effective with slugs’ ultra-sensitive senses. They can’t stand many smells, so take advantage of this by planting these items near the plants you wish to keep safe from the slime.
- Alliums like chives, garlic, and scallions
- Aromatic herbs like lavender, thyme, rosemary, sage, and mint
- Flowers like borage, nasturtium, and French marigolds
- Trap crop with parsley, chervil, and mustard
Remember that not all combinations work. Try new companions each season and in different months, noting what works well. Space your plants properly so they have proper airflow and nutrients. Overcrowding can have the opposite effect by creating a slug-friendly habitat.
Beer Traps
Thinking of a slug drinking beer may sound funny, but it’s effective when carried out properly. Slugs are attracted to the yeasty smell of beer and climb right into your trap if positioned just right.
Build a DIY trap with the following items:
- A recycled plastic container
- Scissors
- Beer or yeast mixture
Trim the container down to a few inches deep and bury them so they’re level with the soil surface. Fill them about ⅔ with beer. Check them daily, removing, cleaning, and refilling as needed. This method won’t deter new infestations, but it will kill any that are already around.
Physical Barrier
Numerous commonplace items make an effective physical barrier to deter slugs from garden beds.
- Copper reacts negatively with their slimy secretions, so they’ll back off if they encounter copper tape.
- Thorny brambles will make it challenging for pests to reach their desired snack. Position these in a double layer around your most prized plants, leaving no gaps they can sneak through. The thorns will make the trek complex and confusing and should deter them from trying. The best part is that brambles are free!
- Salt will dry out a slug’s outer slimy layer, causing fatal moisture loss.
- The scent of human hair and animal fur may deter garden critters, and slugs hate the feel of it. Simply toss it around each week when you empty household hairbrushes and reapply after a rain.
- A saltwater moat around each leg of a working table or elevated planter will drive slugs in the opposite direction or cause them to drown.
Citrus
I was surprised to learn how much slugs love citrus and had to try this hack. If you have a few citrus rinds or find oranges or melons on sale, place them in slug-infested areas. They’ll trap any pests that have flocked to them. Check them daily, discard the slime-balls, and then compost the rinds.
Seaweed
While seaweed flakes are a bit more expensive than other deterrents on this list, they are highly effective. Slugs despise seaweed for its high salt content and beachy stench. Plus, as it breaks down, it offers wonderful garden fertilization, so it’s a win-win.
Keeping a Clean Garden
Again, these pests prefer dark, moist places to hide and breed. Piles of pulled weeds, clippings, prunings, and old hay bales will be pest magnets. The summer is busy, and you may push the task of moving piles to the compost aside, but I promise you won’t regret completing this chore when you see the decreased slug populations and damage.
Garden reminders to deter slugs:
- Remove winter mulches from the base of plants in the spring, especially in high-humidity areas. They create a moist, dark environment for pests to congregate.
- Take garden debris to a compost or burn pile right away. If it starts to rot, slugs will flock.
- Keep unused straw or hay in a barn loft or garden shed. Avoid having it lying on the ground.
- Ensure your soil is well-draining to avoid standing water and moist areas.
- Water in the morning to avoid wet plants in the evenings during peak slug feeding time.
Natural Predators
One of the best ways to have a healthy, thriving garden is by practicing polyculture by providing biodiversity and growing varied root systems in the soil. You’ll naturally build healthy soil, enhance soil microbiology, and attract natural predators for pests, including slugs.
Here are some examples of beneficial predators in action:
- Calendula enriches the soil and attracts lacewings, butterflies, and hoverflies. The aroma may deter pests like slugs.
- Ground beetles and fireflies are natural predators. Attract them with a backyard water feature, nighttime lighting, and nectar-heavy flowers.
- Attract snakes, native birds, toads, and frogs with a freshwater source. Bonus if you have areas of tall, dense grass or cover crops for them to hide in. Hint: These guys all love to feed on slugs, too!
- Growing native plants will attract native wildlife and help create a sustainable and thriving backyard ecosystem.
- Do you have a well-behaved backyard chicken flock? Turn them loose, but keep a watchful eye on them, reeling them in if they start to cause damage.
- Researchers from Oregon State University recently discovered a parasitic nematode, Phasmarhabditis hermaphrodita, that liquefies slugs.
The more diverse your garden, the more Mother Nature will take the reigns. While this type of gardening may take a few years to take hold, the outcomes are worth the effort and wait.
Organic Slug Bait
Granular slug bait is a natural and safe way to control these pests. Organic slug bait is made of mollusk bait and iron phosphate, which causes digestive discomfort. It’s often a last resort because it results in their death, but organic slug bait is OMRI-approved and effective.
Reapply the pellets after it rains and as they naturally break down.
Trap Them With An Ideal Habitat
You can trap and discard slimy pests from the garden by providing the perfect hiding place for them. They love to hide in dark, moist areas. Wooden boards, landscape fabric scraps, large, flat stones, piles of straw, and old buckets are their ideal hangouts. Strategically place these items around, check them a few times a week, and discard any pests present.
Pro Tip: Clear gardens of these mundane items to keep from unintentionally attracting slugs.
Hand Pick
The thought of hand-picking these pests may give you the willies, but it’s highly effective. We know they target young transplants, and you should be more alert during their most active times of the year: spring and fall.
Fill a jar or plastic container with a lid with warm soapy water. Scout affected areas daily, paying close attention to the soil surface near the plant’s base and the leave’s underside. Check inside the heads of lettuce and on the leaves of brassicas, two of their favorite snacks. Plop them into your jar or container and discard them. Refresh your water after each trip.
Key Takeaways
- Delay planting brassicas and lettuces until they are a bit larger, as they can tolerate a bit more damage than when they are very small.
- Use insect netting if necessary to protect young transplants.
- Create a diverse ecosystem and watch Mother Nature control pests for you.
- Be patient while waiting to see the effects of companion planting and attracting native wildlife.
- Reapply slug bait after it rains, as they’ll naturally break down.
- Try various physical barrier options around your most prized plants affected by these slimy pests.
