How to grow vegetables in slug prone areas without baits or traps
Slugs are the #1 enemy of the veg garden in the PNW. Most advice on combating them is nonsense. Here is what actually works for me.
The most effective weapon in your arsenal when you go to slug battle is knowledge.
Apologies in advance, because this is a long post. I promise learning this info will save you loads of time and frustration in the future.
The good news is I’m not here to sell you anything – so keep those hard-earned dollars in your pocket. The bad news: there is no magic potion that you can sprinkle around your garden to get rid of these slugs. Especially if you don’t want to risk serious damage to wildlife.
There’s a few things about slugs that are critical to understand if you are going to be successful. If you just want the planting advice, jump down to my recommendations. But I encourage you to read further to deepen your understanding so this info will become second-nature.
Background:
I live in Slug Heaven: the Willamette Valley of Oregon, where it rains incessantly from October through May. Temperatures are mild with very little deep freezing. As such, slugs LOVE this area in a way that is not common to the rest of the country (especially the east coast where most gardening literature originates).
On top of that, I live in the forest, part of my property is on a shaded wetland where slugs get disgustingly large. Think the size of short, fat snakes that are several inches long.
I’ve got every kind of slug you could imagine on my property. Small ones that like to tunnel around my fattening potatoes. Obese red slugs that like to feed on potato foliage (aren’t potatoes supposed to be slug-resistant WTF?!). Tiny gray squishy ones, fat leopard slugs, banana slugs, black slugs…. uck.
So when gardeners ask me if I’ve dealt with slugs before, my answer is: I’ve gone to war with slugs. And *I* won. Well, mostly. I harvest large quantities of food from my garden every year - my freezer and pantry are full of food. I’m even kind of ok at growing lettuce during certain times of the year.
But it wasn’t always this way. There was a time when I thought my efforts might be futile and I should just give up.
I’ve tried every remedy you’ve possibly read about.
I’ve spread coffee grounds, egg shells, and ash around my plants with absolutely no effect.
I’ve farted around with copper only to have the slugs laugh at me.
Diatomacious earth: If I wanted to F*** up my lungs I’d take up smoking again. Nevermind the considerable expense that would be required to mulch your whole yard in the stuff. And, hello? DE only works on insects (not slugs at all) during dry weather, when slugs are inactive anyway. Tell me, where do we live again?
Using wooden boards to trap slugs and then dispatch them in the morning seems to do nothing to lessen their presence in the garden… they just keep on coming. Trust me. I tried this with a dozen boards for over a month. If my back could talk, it would cuss me out for even trying this one.
As for poisons, there are two routes you could try. There is the non-organc route, with toxic results to not only slugs but wildlife in general. That’s a big nope for me.
On Iron phosphate. The “organic” stuff. I won’t use the brand name here as I don’t need some corporation coming at me with a legal pitch fork. I’ve shelled out enough cash to buy a car for those earth-polluting plastic jugs that have been shipped all over the country. The results: I don’t know how many times I’ve gone out at night and watched slugs munching away happily on my plants or mushrooms. Bait unconsumed mere inches away. And yes, I followed directions on application. I’m not at all convinced that iron phosphate does anything.
Beer traps. Oh how some gardeners love those disgusting things. Do yourself a favor and look up the videos of beer bait slug traps. You’ll see what I observed in an experiment I did, when I was trying to figure out why my beer traps weren’t working the way I thought they would.
I collected roughly 30 slugs, and put them in an enclosed cooler with a beer trap at the bottom. Over the course of the week, I opened the lid several times a day and saw various slugs happily getting sloshed on the beer buffet I provided for them. Only two slugs out of 30 died in a week. The rest of the slugs I just made even fatter and happier. Expensive, gross, and a hell of a waste of time. Save your beer for yourself.
Salting. Dude. Watching a slug die from exposure to salt is pure satisfaction. And also super gross. They end up a pile of disgusting goo that sticks to your edible plants. I prefer my salad dressing without slug guts, thank you. Oh also salt buildup in your soil isn’t cool.
Scissoring. (ahem) I’m talking about going out at night with a flashlight and cutting them in half. But the slugs just… keep coming… and coming. Like The Walking Dead.
And here’s a gross fact for you: slugs love to eat other dead slugs. Often you’ll go out at night and see multiple slugs feeding on a deceased slug carcass that you snipped the night before. To me this begs the question: does this mean we’re just attracting more slugs to our garden when we kill them? Does the aroma of dead slug allure other slugs from afar? Barf.
To lots of gardeners, these traps and other methods do **seem** to work. But if you live in Slug Heaven as I do, slug pressure is so high that none of these methods work at all. Why do they *seem* to work for some people? I promise, I’ll get to that later.
Important fact #1: slugs go (mostly) dormant in our climate during the summer.
Surprised? I was too. Here’s how I learned this fact:
In one of my scissoring experiments, I spent about a month going out every night and observing. And because I can be a little OCD at times, I also counted while out on my murder quest.
During April and May when the rains were heavy and the ground wet, I would observe about 150 slugs every night. No amount of chopping up their slimy little lives seemed to make a dent. At the end of the month, I was still observing roughly 150 slugs in my food growing areas.
However, when the dry spell starts in June, slug activity drops off dramatically. Once the ground is dry-ish and temps warm, I consistently see roughly two or three slugs a night. All through the summer. BIG difference.
I believe this is why gardeners swear by the above slug methods. Gardeners get out in the spring happily planting away. Then the slugs come out. Once the damage is noticed, the gardener rushes out to apply whatever (un)solution they read about on Joe Blow Blog. Problem is seemingly solved. But what really happened is that the summer drought came and the slugs went (largely) into dormancy anyway.
Can I just say… I have mad respect for what local university extension offices do. But it sure would be nice if our local office here in Oregon would put a priority on this issue and study it instead of providing nonsense advice. (Seriously OSU, still recommending DE? Sheesh).
#2 Slugs have a particular appetite for young plants, and for leaves that are deteriorating.
Young plants, especially seedlings, are delish to slugs. It helps to start your seeds indoors (or purchase starts) and plant outside only when conditions are favorable for rapid growth. If direct seeding, it can help to wait until slug predation has slowed considerably.
Slugs also have an appetite for older leaves. Once slugs find those older leaves, they like to stay and tunnel inside the heads of your cabbage or lettuce.
On kales, it helps to remove the oldest leaves for harvesting in lieu of harvesting the whole plant. Same with lettuce. Cabbages and other brasssicas you can simply remove the oldest leaves if they are starting to fade and yellow.
#3 Plant when soil temperatures are the right temp for the species.
I used to run around and try to plant everything early, so that I could have early harvests. Slug pressure has changed this habit for me, because if the soil temperature isn’t right when you plant, the seedling is unlikely to grow. The plant is like a sitting duck for the hungry slug that comes along.
Grab a thermometer, stick it in the soil, and refer to planting advice from seed manufacturers. They will tell you what temp the plant is going to grow best. Eventually you’ll get a better feel for favorable conditions for each type of plant.
Instant read thermometers from the kitchen are fine. Just wash them well before you stick them in your turkey.
Side note: I don’t worry about any of that hardening off nonsense. Once my plants are to size, I put them straight into the ground and they do just fine.
#4. Encourage rapid growth.
Encouraging rapid growth moves susceptible seedlings beyond that stage where they are most susceptible.
Here comes some garden blasphemy. I use a bit of miracle grow on my seedlings. Once they have a true set of leaves, until they are set out into the garden. Just a little bit. Like a teaspoon in a gallon of water. A little box of this stuff lasts for years and is cheap. I learned this trick from Steve Solomon, who wrote the best book on growing veg’s in our region: Growing Vegetables West of the Cascades. His advice is otherwise mostly “organic”.
If the blue stuff makes you squirm, you can try fish fertilizer. If the smell doesn’t make you puke, that is. My understanding is that this fish goo doesn’t quite have the right ratio of nutrients, but it will help get your plant growing so that it can seek out those other nutrients. Or you could put a little kelp in the mix.
#5 Encourage predators.
I have two distinct areas in my garden. One is where there is a considerable presence of natural predators including snakes, frogs, alligator lizards, and other slug munchers. The area without those natural enemies seems to have substantially more slugs.
The predators seem to be concentrated around where there is a natural creek/wetland. There is also an abundance of rock and boulder hidey holes. Mimicking their preferred habitat may help you draw them in.
Snakes also seem to **really** like black plastic sheeting. I would never encourage purchasing new plastic just for this purpose, but if you happen to have any visqueen or other black plastic for repurposing you will likely find snakes calling it home underneath there. I have a few sheets of plastic I use for discouraging weed growth, and every time I move them, there’s like four or five snakes in there. Both garter and rubber boas seem to think the heat and humidity under that plastic is prime real estate.
#6 Scout.
No matter what you do, you will still have some slugs in the garden. When you plant out new seedlings, this is the time to pay careful attention.
If you see any sign of slug damage, go out at night with a flashlight for a game of seek and destroy.
If slugs and snails are hungry and find something they like, they are going to come back. Chances are, you will find the offender at or near where you observed the damage during the day.
Make sure to move the dead slug to another area prior to destroying them though, so as not to attract more slugs.
#7. Plant more than you need.
Slugs seem to really like strawberries. I had an “aha” moment when I visited a several acre farm only about 2 miles away from me, that has nothing but strawberries that seem undamaged. I asked the farmer there what they do to combat the slugs. They said that the very first ones get slug damaged badly, but once the strawberries start ripening in droves, the slugs can’t keep up. They don’t use any products at all.
When I first started growing shiitakes, they were often badly damaged by slugs. Since I love shiitakes and they seem to otherwise grow fairly easy for me, I tried the strawberry farmer’s advice and grew many more. Now I get some slug damage but it isn’t too bad.
Lettuce and brassicas are plants that particularly sensitive, and you should practice planting more than you need. Your neighbors and friends will happen to thank you if you have excess.
#8 Remove hiding places.
Where possible, remove board and rocks and things that slugs like to hide under during the day. This advice is totally not feasible for me, with about a million rocks and boulders as well as downed wood everywhere from the forest. But keeping this in mind will help avoid plant losses.
Also reconsider planting beds with sides (more on that later).
Specific planting advice.
I’m just one person, still figuring all of this out. Take this info with a grain of salt and know that this is just what works for me.
Cucurbrits: cucumbers, squash, melon, etc.
-These seedlings are a FAVE of the slug so be particularly careful here. Once the plant transitions from seedling stage they are far less likely to appeal to the slug palate. Never seen a slug on a mature plant.
-Here’s what I do: pay careful attention to the long range forecast in late May/early June. Once a long, dry, warm spell is expected to come, start cucurbrits indoors. Once they’ve got a full set of true leaves, plant outdoors and scout as needed.
-If a freak rainy spell comes along, you could slow the plant down so it doesn’t outgrow it’s pot by setting it outside. Hopefully up way high and out of detection of the slug.
-Pay close attention. Be prepared for some losses on cucurbits and ready to re-start some seeds should you lose some plants.
Corn.
I don’t have much experience with corn other than knowing that corn enjoys warm soil temps and heat which I lack on my property. I’m doing some experimenting this year, and will treat similarly to cucurbrits.
Beets/chard.
-For me, the easiest has been to direct seed in the space I remove garlic from early summer (late June/early Julyish). Keeping the area damp so the seeds can come up does not seem to attract many more slugs.
Strawberries: choose later ripening varieties, and/or grow a few extras for the slugs.
Basil.
We’re big fans of pesto over here. Basil also works out well direct-sown in the space where I pulled garlic out of early summer, planted in the same way/timing as for beets. Good use of space.
Alliums: garlic, onions, shallots, are all slug resistant.
Asparagus is not bothered at all by slugs.
Kale and other brassicas:
-I start about a dozen plants indoors in February and plant out a few weeks later, perhaps mid or late March.
-I only grow a hybrid lacinato kale, with occasional other brassica plantings. I find kale meets most of my needs for this plant family. I grow a hybrid because it gets up and growing *very* fast, which I need to outwit the slug and the beastly cabbage root maggots (blog post about them to come in the future).
Parsley.
-I start my parsley mid-april to mid-may (or later if you haven’t gotten to it), and plant out once the ground has warmed up some early June.
-In my house, parsley is a veg, not just a garnish. When the slugs don’t eat the seedlings, it makes a big part of my diet. However, slugs love parsley seedlings so be careful. Once it gets going, it keeps going strong until the winter.
Carrots and celery: I don’t plant. Too easy to buy at the store.
Peas, favas, garbanzos are all grown about the same way.
-I start mine as early as mid-January, indoors, contrary to gardening advice that they need to be direct sown.. Check out Charles Dowding’s video on the topic. Once several inches tall. As of 2/16/2024 my sugar snap peas are already six inches in height and super happy.
-Also consider fall sowing for overwintering. I haven’t tried it yet.
Beans of all kinds I sow indoors as well for multiple reasons. Typically I’ll sow early to mid-may and set out a few weeks later.
Parsnips: are some of the easiest veg’s to grow in our climate. They seem to require a little cold stratification, which means planting when it is super cold. Slugs could care less about parsnips, so direct seed as early as January or February or even in the fall.
Miner’s lettuce and corn salad are two greens that slugs leave completely alone. Bonus: miner’s lettuce is native here, and both of these will reseed in the garden should you let them go to seed. Direct seed winter to early spring and again in fall.
Tomatoes/eggplant/pepper:
-Start indoors mid-march to mid-april. Set outside mid to late May or even early June.
-Some solanums are weirdly more slug sensitive than others. (OSU here’s another area where you could help us out). It seems that most of our tomatoes do just fine, so long as you plant them out when it is warm.
-In my experience peppers seem to be super sensitive so wait until even later.
-The tomato Sunrise Sauce has gotten devoured several times in my garden, but I still grow it because it is so prolific.
Potatoes are supposed to be planted early in the season, but mine always have some kind of slug damage. They do not do so much damage as to ruin the whole crop though. I’ll be doing more experimenting in the years to come, though flea beetle damage on the tubers has discouraged me from fooling with them too much.
Lettuce: OOOH do slugs love them some lettuce. Be particularly careful here.
-My early summer lettuces get started roughly early April to mid-may, setting out once they have several sets of leaves. Plant more than you need, as it is inevitable that some will get eaten. Scout religiously.
-I’m still experimenting, and there are some lettuces that grow better in cooler weather. Though, those tend to bolt before you can eat them. I have also heard that some lettuces are slug resistant because of reddish anthocyanin coloring. (OSU please do some research on this).
Spinach: I don’t have a ton of experience with. My kale provides so much fodder that I don’t put in much effort. But, my son occasionally will eat the baby spinach leaves that I get from plants set out late winter. I have also read spinach is fabulous wintered over.
Purslane is well known as a weed, but slugs leave it alone, and is a good hot season salad green when lettuce just wants to bolt. There are cultivated varieties that you can seek out. Look at Wild Garden Seed’s website for an awesome selection that is much larger and less tedious to pick.
Turnips, rutabagas and radish: I don’t have enough experience with. Radishes do seem to do very well for me in terms of slugs, but they almost always have root maggots so I don’t bother. They are cheap to buy anyway.
Chicories/endive/raddichio: I don’t have too much experience with, but they seem to do well from summer plantings in terms of slug damage. My problem is the GD deer seem to always find my garden in the late summer/ early fall, and they really like these so don’t bother.
Ornamentals:
Don’t buy ornamentals that are prone to slug damage. Often you won’t know until you bring it home and it gets devoured, so spend some time doing research. Ask gardeners in this area wether they’ve had success with X variety of plant.
And, uh, good luck on those hostas.
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