Slugs come in all shapes and sizes

Why do my plants have holes in their leaves?

TL;DR : Creepy crawlies, creepy slimies, and other animals. There are many ways to get rid of them, so don’t resort to chemical warfare just yet.

Welcome to the “What is eating my plant?” series.

Part One : Gastropods and large animals

Part Two: Insects and small animals

Part Three: Population control for insects

This part concerns gastropods and animals. To learn more about the most common insect infestations read our next article and for the best solutions to control your insect population please head to our article on population control for pests.

If you’re here, you’ve probably encountered a very common and aggravating issue for most gardeners: your precious plants have holes in their leaves. Annoying right? How could this happen? Well there are several reasons. So what’s eating your plants? Do you want to get rid of it? And more importantly, how do you get rid of it?

While the damage done by animals or bugs feeding on plants is unsightly, most plants can survive an average infestation. The only plants you need to worry about are very immature plants and seedlings that may not survive either the leaf or root damage caused by different pests. It is a horrible feeling to lose a seedling you just planted to an attack.

Sometimes pretty much everything in your garden may have a few holes eaten into some  leaves. This is normal. Apart from not being very esthetic or nice to look at, this isn’t really something to worry about. All animals need to feed (you probably know that, because you are an animal too after all) and you should let them get some lunch.

A whole range of lovely little critters can cause significant damage to your tender green plants. At this point, you have probably noticed this, and depending on the plant and the type of damage you’re looking at, we can point you in the right direction. Probably the most common nuisances in the average garden are terrestrial pulmonate gastropod molluscs. Yes, that’s right: slugs and snails!

Slugs and snails

These holes in your plants may also be the result of slug damage. These critters are primarily nocturnal feeders, so they may be not noticeable during the day. If you see slime on or around your plants and holes in them you are probably dealing with these gastropods. These molluscs hide under mulch, rocks, and other objects during the daytime and feed at night. They pose the biggest threat in humid weather so you’re more likely to encounter them at the worst moment possible : in spring when all your plants are still seedlings or young and fragile. Another complication is that these little critters love to eat the soft, tender and delicious parts of plants : the brand new leaves.

Slug will nibble on many plants.

We’ve had a lot of problems with these while trying to grow Sequoias (Sequoiadendron giganteum) from seeds. Once they started shooting up with their first leaves a slug would just climb up and put the plant to rest. This happened quite a few times as they would just hide under the flower pots during the day and come out as soon a the sun set. We would explore the garden with flashlights to look for the remaining little monsters.

How do I get rid of slugs and snails ?

There are many different types of slugs (I mean there are even Banana Slugs : The ones you are most likely to encounter are the Grey Field Slug, the Garden Slug and the Black Slug (which is not necessarily black apparently). As said above, you can wait for the sun to set in spring (this usually happens pretty early) and go outside with flashlights to finish them off. This is definitely easier (and more fun) if you are not alone to do this or if you have a headlamp at least. We have chickens, so giving them slugs and snails as treats was a little bonus. They also helped us dramatically reduce the population of these critters to a manageable amount.

There are a few rather effective ways to reduce the population or to stop them from attacking certain plants. Here are some ideas, just pick the one that suits you best

  • Trap these pests under boards, cabbage leaves, flowerpots, or other objects, then scrape them into a bucket of soapy water to dispatch them. If you have old cardboard boxes a great way to trap slugs is to just leave a wet one lying around in your garden near a spot you usually see slugs. In the morning just look under it and you can find a little army of slugs hiding for the day. Pick them off and dispose of them. You can feed them to your chickens or to your fish (if they are large enough, in a fish pond or the ones you use for aquaculture) and kill two slugs with one stone!!
  • Lure them to containers filled with stale beer (get the cheap stuff): Set containers with the lip at soil level so that slugs and snails are lured in and drown. Renew as often as you wish (just don’t drink all the beer, leave some for the slugs).
  • Surrounding plants with a band of wood ash (if you use wood for your fireplace or your barbecue you can use these ashes) discourages them as well,  as long as you renew it frequently. If you put a snail on wood ash (or poor it on it like salt) you will see it bubble up and then shrivel up. Indeed when offered a piece of salad covered with acetic acid, for example, snails will start to foam to protect themselves from contact with the unpleasant substance. This work with ash too. Slime and air is pumped out to help the snail protect itself, but unfortunately, if enough salt or ash is poured on the snail, it will dry out and shrivel up. This is why they usually avoid having to pass through wood ash or salt. But ash lasts longer in the garden than salt does. You can also use ground eggshells, oyster shells or coarse sand as these will cut the snail, making your plant seem to be less worth it. Do not forget to take into account that large quantities of wood ash will raise your soil’s pH. This is great if that’s what you need, not so much if you need an acid soil. Eggshells and oyster shells will add calcium to your soil, an element plants are sometimes missing. Finally sand may increase the draining power of your soil.
  • Attracting predators or birds (hence the chickens, just keep an eye out for your other plants or the chickens may soon be the ones making holes in them), toads, and other beneficial animals also helps control slugs. If you like birds and have some extra time on your hands, you can collect slugs and snails and toss them to wild birds in the morning; they will learn to look for slugs in your area over time, and you won’t have to help them look for slugs for long. Hedgehogs are also slug-lovers and they are really fun to have around. We call ours Max. You can also introduce ground and tiger beetles into your garden. Most ground beetles are natural predators of slugs. Common predaceous ground beetles (family Carabidae) include hunting caterpillars, beetle grubs, grasshoppers You can entice wild beetles to stay near your plants by providing dry refuges under stones, grass, or straw. This allows the beetles to hide from predators, making your garden an attractive home. The snail-hunting Scaphinotus beetle, with its long narrow head and thorax for reaching into snail shells, is an great garden helper. The best known predators for slugs : frogs, songbirds (like thrushes or redwings), ground beetles, hedgehogs, common shrews, parasitic nematodes, marsh flies (parasites called Tentancera elata & Eurthycera cribata), slow worms, centipedes, common newts, ducks, hens, rooks, jackdaws, jays, magpies, starlings, blackbirds (which eat snails in winter), fieldfare, gulls, owls, robins, toads (they were once commonly kept in greenhouses to control slugs & snails), moles, common lizard, foxes, mice, rats, testacellid carnivorous slugs. See if you have any of these laying around in your garden and try to encourage them to stay there.

We do not recommend using any chemicals to control these gastropods population. These are not only toxic for your animals – I’ve already seen cats die after ingesting some of these little blue pills (metaldehyde) ; think about your neighbors pets also – but they are also toxic for your soil and its life. If you eat anything that comes out of your garden, then you too are ingesting these destructive and harmful products.

If none of the solutions above work for you (sorry, but you are probably doing something wrong) you can try organic slug and snail bait. The active ingredient in this product is iron phosphate.

You can also try growing more plants that drive slugs away :

  • Herbs like ginger, garlic, chives, mint and chicory.
  • Vegetables like bitter greens are generally less appealing to slugs than sweet greens. Try planting kale, spring cabbage, or sprouting broccoli. If you prefer these then that’s a sweet bonus (or rather a bitter one).
  • Hosta varieties with blue leaves are more resistant to slug attacks.
  • Flowers for full shade: Astilbe, Dicentra, Digitalis (foxglove), Lobelia, Viola (some pansies and violets). Also Ranunculus (buttercups) and Vinca, but these spread rapidly.
  • Flowers for partial shade: Phlox, Campanula, Hemerocallis. Also Mentha, but this is also one that spreads rapidly so watch out for that.

Growing chives is great to fight of slugs and they are delicious

Animals (of all sizes)

Ok, we all know if your have holes in your plants the chickens are to blame. They got out of their pen again didn’t they? Just admit you forgot to lock them up this morning. It happens to everyone. You don’t have chickens? Well then it has to be something else.

Various animal pests can also chew leaves and plant parts, so don’t overlook them.


If you live near woods, deer may eat entire plants, but they can also chew off the tops of your vegetables. You might get to spot them in the morning if you’re pretty lucky. The only ways to keep these away from your vegetables are probably to fence in your property or at least your crops or to get a good guard dog to scare them away.


Another animal that could creep into your vegetable patch from a nearby forest is the rabbit.  Rabbits are always eager to chomp away at all manner of vegetable plants. You may want to plant some of the plants that rabbits are particularly fond of if you want the keep them away from your most precious crops. Planting rabbit favorites like beans, peas, parsley or rosemary may save your garden if you plant them further away. You may also try favoring crops they aren’t usually drawn to around your garden to conceal their favored ones. Here are a few examples : peppers, cucumbers, tomatoes, corn and squash.


Crows have also been known to pull up seedlings and consume them, some other birds have the same tendency.

And chickens, definitely chickens.

Your hen will eat slugs but she might also eat your plantsYour hen will eat slugs and snails but she might also eat your plants if she runs out of yummy slugs

This is the end of the first part of this series. Keep on reading to our article on insect infestations if you believe your plants are also under siege from all sorts of bugs and beetles and you’d like to identify them, or skip directly to insect population control if you’re looking for ways to get rid of them.

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