Cover Image: CC0 by Theo Summer

Plain and simple: Invasive slugs suck.

Or more accurately, they nibble, they decimate, and they wreak havoc on my beloved plants.

If you’re like me, you’ve probably tried every organic method under the sun to keep these persistent pests at bay - only to find your garden is still full of slugs.

I’ve tried some pretty wild experiments to organically distract slugs from my precious plants—or at least corral them somewhere manageable.

Here are some strange - and some commonly recommended - techniques that I've tested in my own garden that didn’t work. Here’s why:

• Fennel Fronds Magic: After a rain, slugs seem to adore fennel fronds. Clip some off your plant and scatter them around the garden. Collect the slugs one day after the rain. Prepare to be amazed (and possibly horrified) by the sheer number of slugs. Unfortunately, this just gathers them without solving the problem.
• Debris Patrol: Slugs love to hide in garden debris—wooden planks, under pots, old fence posts. These spots can help you collect them, but it also becomes a breeding ground if you’re not up for picking them one by one off a wooden plank. It’s a trade-off: a clean garden or a daily walk with a soapy bucket of water. Your pick.
• Beer Traps: Create irresistible slug taverns with cheap beer. These traps lure slugs in for a swim they won’t return from. However, you might feel guilty for encouraging such habits, and it only offers temporary relief. My slugs don’t seem to have a strong taste for the stuff, anyway.
• Chamomile Barrier: Plant chamomile everywhere—between each brassica, a foot of chamomile. While this might deter some slugs, it doesn't eliminate the problem. And planting half your garden in chamomile isn’t so practical. On the plus side, you’ll have a lifetime supply of tea.
• Blackberry Barbs: Guard garden bed edges with nature’s barbed wire—blackberry stems. Be prepared for disappointment, though, as slugs don’t care about thorns. Instead, you might end up with pricks on your hands.
• Coffee Grounds: Slugs don’t care really.
• Egg Shells: Slugs, like honey badgers, don’t care.
• Pennies: Save your pennies for a rainy day, but unfortunately they don’t keep slugs at bay.
• Black Tea: Meh.

…and the list goes on.

Short of putting up signs that say, “Hey Slugs, No Trespassing,” I’ve tried what feels like everything.

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Discovering the Real Solution: What Actually Worked for Me

So, do you want to know what has actually worked for me - and what slugs hate the most?

You might not like the answer.

It’s patience.

Time and patience.

As my neighbor has said “You just need to deal with slugs for three years before the birds and other insects find them.”

I know, that’s not the quick fix you were hoping for. You wanted a blog post that lists 10 things slugs despise (number 8 will surprise you).

But trust me, creating a balanced ecosystem yields actual lasting results in the long run. And there are things you can do now to help your garden to thrive.

Creating a Balanced Ecosystem

If garden slugs are a persistent problem, it might indicate that your garden's ecosystem hasn't fully matured, typically within the first 1–4 years.

Because what really needs fixing isn’t just the slugs—it’s the balance of your garden’s ecosystem.

Over the years, I’ve noticed that the type of plants and the overall garden setup play a significant role. These factors impact the effectiveness of different slug control methods.

My garden is located in a temperate climate, with a mix of vegetables, herbs, and flowers. I’m in the Pacific Northwest, where it rains for 9 months of the year. The slugs love that.

In this challenging environment, I've realized something important. The best way to naturally control slugs is by creating a balanced ecosystem.

And also to understand that you're never going to fully eradicate gray garden slugs.

After much experimenting, I've discovered a few key strategies. These have made all the difference.

Here’s how I created a balanced ecosystem to solve my slug woes:

1. Attract Birds:

Birds - especially robins - are slug fiends. Attracting birds to my garden has been extremely beneficial in my quest to reduce slugs organically.

• Bird Feeders + Bird Baths: Setting up bird feeders and bird baths has made my yard a haven for these helpful birds.
• Seed-Head Plants: I also intentionally grow plants with seed heads that they enjoy, like echinacea, sunflower, millet, amaranth, and goldenrod.

2. Encourage Beneficial Insects:

Some insects find slugs to be quite tasty. Create a habitat for them to create a more diverse ecosystem.

• Beetles: Things like beetle bumps and diverse plantings of herbs and flowers will attract beetles, who are known to also enjoy a tasty slug supper.
• Diverse Plantings: Planting a variety of herbs and flowers attract beneficial insects to the garden to naturally control slugs.

3. Host Amphibians and Reptiles:

Frogs, snakes, and salamanders are all natural predators of slugs.

• Logs and Leaves:  I leave a couple of logs on the edge of in-ground garden beds. These logs are then covered with leaves and organic hay. To my delight, I found a salamander under one, indicating a thriving habitat
• Mulching: I also mulch with straw and chop & drop methods, which the snakes appreciate. Since my summers are very dry, the slugs don't really populate the mulch during the main growing season. It's the spring and fall when they are most active. Experiment with mulches to see what works best for your climate.

4. Sustainable Practices:

Some permaculture principles that are echoed in regenerative gardening naturally help reduce the slug population.

• Maintain a Healthy Compost Pile: Well-managed compost piles can attract beneficial creatures into your garden who will help you with a nature-based slug solution. A balanced compost is ideal. It shouldn't be too dry or too wet.
• Plant Diversity: In my experience, it really does help to plant chamomile with brassicas. Other herbs work well too - lemon balm, oregano, thyme, and nepeta are some that in my garden, seem to do the trick. At the end of the day, the more plant diversity you have in your garden, the more robust and resilient it will be.
• Plant Trap Crops: Marigolds, mustards, and daikon radish tops are all very scrumptious to slugs. Planting these as companion plants helps deter pests. This keeps them away from your main harvests.
• Keep it Organic: Organic inputs help your garden’s microbes, insects, and other animals to thrive. While this may mean pests survive too, your pest predators need those pests in the first place in order to be attracted to your backyard habitat.
• Enhance Soil Health: Healthy soil is the foundation of everything, really. Regularly add organic matter, mulch, and keep plant roots in teh ground to promote beneficial microbial activity. Healthy, well-drained soil discourages slug populations.

Action Steps

1. Set Up Bird Feeders and Baths: Attract slug-eating birds to your garden by providing food and water sources.
2. Create Beetle Habitats: Establish beetle-friendly environments with diverse plantings and beetle bumps.
3. Provide Shelter for Amphibians and Reptiles: Leave logs and mulch in strategic areas to attract salamanders, frogs, and snakes.
4. Maintain a Balanced Compost Pile: Ensure your compost is well-managed to attract beneficial organisms.
5. Promote Plant Diversity: Interplant herbs with your crops to create a less favorable environment for slugs.
6. Use Trap Crops: Plant marigolds, mustards, and radish tops to lure slugs away from your main crops.
7. Stay Organic: Use organic inputs to support a healthy garden ecosystem.
8. Enhance Soil Health: Regularly add organic matter and mulch to promote beneficial microbial activity.

By following these steps and focusing on building a balanced ecosystem, you’ll not just win the battle but the war against slugs.

Other things to try:

• Cedar wood chips: This is an investment. But if you’re not in the drop off zone of a Chip Drop and need to buy wood chips for your pathways, go with cedar. I learned from the Millennial Gardener that this deters slugs, and I did notice a difference after applying it.
• Sheep’s Wool: In some areas, sheep wool is inexpensive and easy to come by. Mulching your garden with sheep’s wool can help keep slugs at bay. Wool pellets are also sold if you’re not in an area with a large sheep population.
• Beneficial Nematodes: If you’re outside of the United States, you can likely source Phasmarhabditis hermaphrodita nematodes that feed on the slugs. In the US, it’s hard to come by the specific species of nematode, as they also go after endangered slugs so they are not allowed to be sold.
• Drip Irrigation: Avoid overhead watering, as slugs will be attracted to the water droplets on your plants leaves and start munching away. Surface watering - or even better, drip irrigation - prevents this.
• Watering Time: Water your garden early in the day so the surface soil is dry by evening, when slugs are most active.

Nerd out: Slug Science Stuff

• Nematode Research: Oregon State University Professor Dee Denver and Associate Professor Rory McDonnell are researching the P. hermaphrodita nematodes that help with non-native garden slug control, and are looking for other nematode species that can contribute to the goal
• The Common Garden Slug is Invasive: Don’t feel bad killing the common garden slug - Josh Vlach, entomologist with a focus on invasive species, note that all the pest species in the PNW are not native to the region!
• Don’t kill all slugs and snails blindly: With that being said, it's crucial to recognize that some native slugs and snails are beneficial for your garden and should not be eradicated. Rebecca Lexa, a nature educator and master naturalist, reminds us that not all slugs are bad - some are even important within our local ecosystem and food web. To kill all slugs blindly could do more harm than good in the long run.

Frequently Asked Questions

Q: Do slugs only come out at night?
A: While slugs are most active at night, especially when it is damp, they can also be found during the day after rain or in shady, moist areas.

Q: Is salt a good method to get rid of slugs?
A: While salt can kill slugs, it's harmful to your plants and soil. It's a quick fix but not a viable long-term solution.

Q: How can I attract birds to my garden for slug control?
A: Attracting birds can be beneficial. Set up bird feeders and bird baths, and grow plants with seed heads that birds enjoy, like echinacea and sunflower.

Q: Are there any plants that naturally deter slugs?
A: Yes, plants like chamomile, lemon balm, oregano, and thyme can help deter slugs. Planting these among your crops can offer some protection.

Q: What should I do if my compost pile attracts pests?
A: A well-managed compost pile should be balanced—not too wet or too dry. This balance attracts beneficial creatures that help control pests naturally.

Q: Can I use coffee grounds to deter slugs?
A: Coffee grounds are often recommended, but in my experience, they don't significantly deter slugs. It's worth trying if you have them on hand, but don't rely solely on this method.

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Now, when I’m looking out the window admiring my garden, I often spot robins, thrushes, and sparrow feasting on slugs and other bugs in my garden. These birds, happily pecking away, signal to me that the ecosystem I have patiently nurtured is in balance. Yes, the slugs still exist, but they are not causing total destruction. Instead, the slugs have met their match, not through quick fixes but through time and nature's own design. Seeing these birds foraging for slimy protein is always a reminder that patience and a little help from our feathered friends can truly transform a garden.

Take it from me, focus on building a balanced ecosystem and you’ll not just win the battle, but the war against invasive slugs.

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