11 Apr 2014

A slug is a slug no matter how small ...

Gastropod, the biological name for a slug, literally translates as stomach foot.  At any time of year, it's good to have some strategies in place to control them but it's especially important in spring when tender little plants and seeds are about to go out into the garden.


I googled the word 'slug' … 


I was reminded of this when my cousin mentioned that he'd returned home to find half his marigolds were missing after being away for just a few days.  According to this fact sheet, 95% of slugs are underground munching on seeds, laying eggs, chomping roots. They've been around since the Ice Age so nothing we gardeners do will permanently eradicate them, especially after the nice wet start to the year that the UK has just had. There is one slug that apparently prefers to eat other slugs rather than plants and that's the Leopard Slug. I found several last weekend during my slug search; not knowing any better, they live no more.  Next time I'll spare these.

Friend: Leopard slug. Easily identified.


Looking for further slug facts, I came across a link to an article about Killer Slugs which made very disturbing reading. The so-called Spanish slug (actually, probably not from Spain at all) was identified by the Head of Entomology at the John Innes Centres in Norwich although they may have been in the UK since 1954.  He found hundreds of these very large slugs in his garden and did a bit of research. They're a voracious and invasive strain and have been known to eat each other if nothing better is available … for instance, native slugs, dead mice, animal faeces or a row of lovingly tended lettuces.  They live for up to a year and will lay about 400 eggs in that time which hatch in three to four weeks. Slug eggs and baby slugs are lurking under leaves and in the soil ready to slither into action when the weather warms up and it's predicted that this year will be another bumper year for these crop decimators.

So whether your garden or plot has Stealth Slugs, Killer Slugs, garden slugs, tree climbing slugs or slugs in a rainbow of colours, it's time to take action. My favoured method at the moment is search and destroy: swift decapitation with the edge of my copper trowel then throwing the bodies out for the birds. I hope in this small way I'm winning the war without unbalancing the eco-system.

For gardeners of less clinical disposition, I've given some thought as to how to best be prepared for the annual slither and munch fest.

Clear leaf debris.  Fallen leaves provide a protective winter mulch for the soil. Most leaves will not decompose fast enough to be of benefit to the soil so should be raked off anyway in the spring.  Ditto any decaying/old leaves or other matter; these should be cleared to allow light through to the emerging shoots. This year, I've cleared debris sooner to deprive overwintering pests of their warm, dark shelter.

Coffee grounds.  This was touted as a good slug deterrent a few years ago.  Living near a deli with excellent coffee, I had access to copious amounts of coffee grounds; I tried it but remain unconvinced. Allegedly slugs are deterred by caffeine but the same grounds will make seeds and tender seedlings very unhappy. (I tried coffee grounds on a test bed a couple of years ago and nothing grew there.)  A laboratory test of Starbucks grounds showed them to be slightly acidic (pH 6.2) and nutrient rich (nitrogen, potassium, phosphorus, magnesium and copper), probably a bit too much for seeds and seedlings to cope with.  In 2012 the RHS alerted gardeners to an EU ban on using coffee grounds as an organic pesticide - article here - although your behaviour won't be considered subversive if your grounds are applied as a mulch.  If you have an excess of grounds (which I have after stopping for coffee at Costa coffee on the M3 where they bag up the grounds for customers to take), they make an excellent addition to compost or can be added to blueberry shrubs, camellias or other plants preferring an acidic soil or ericaceous compost. Grounds added to the soil should be incorporated well; once the grounds have been broken down by soil organisms, the minerals they contain become available to plants so grounds make a good slow-release fertiliser.

Egg shells. Killer slugs have been seen eating snail shells so I suspect mulching with egg shells won't help much. Last year, I mulched around my broad beans with a large dish of washed, crushed and baked eggshells. As baking eggshells hardens them up, I thought the added crunch might be an extra deterrent. I found slugs in the soil but my beans were okay, and the eggs shells were dug into the soil afterwards. This treatment made no difference to my hostas which disappeared overnight.  If nothing else, adding eggshells to the soil will slightly boost calcium. All plants need calcium, with apples, brassicas, legumes, potatoes and tomatoes especially so.  Don't add eggshells around plants such as blueberries as they prefer an acidic ericaceous soil - eggshells are alkaline.

Nematodes.  This works .... but only for a few weeks.  Nematodes destroy slugs from the inside and need to be watered onto the soil during  damp or wet weather.

Salt water / hand picking.  I introduced The Sluginator to my slug controls a few years back. It's a large plastic bottle containing salted water. (Hot water is quicker and so slightly more humane.) It needs a lid, otherwise slugs will climb out.  Regularly slug patrol your patch at dusk, dropping any adult slugs into the salt water which kills them.  I'm squeamish about touching slugs so keep my gardening gloves on.

Beer traps/grapefruit shells. Slugs can't resist a good jolly up and will wend their way towards the pub of doom, never to emerge again.  Sink a plastic container (eg cut down milk carton) into the soil, part fill with beer, empty when gruesome. Grapefruit halves placed dome upwards on the soil will attract slugs. If propped up slightly so the slugs can get under, you'll find several lurking within come morning.  Then you can decide what you're going to do with them.

Copper strips.  These are reputed to give a mild electric shock to slugs as they try to cross them, the theory being that they will turn away from this unpleasantness. Buy tape to put around the rim of pots,  beds and greenhouse shelves. The drawback is that slugs can arch over copper strips and the strips are not cheap to buy.  I've had some success making copper collars from the inside of tomato paste tubes - cut open, smoothed out, trimmed and placed on the soil around my sprout seedlings.  No slug damage ... maybe they just weren't interested, or maybe it was because I used my ...

... Copper tools.  I use a PKS copper trowel which is reputed to deter slugs. In the wet summer of 2012, although I had quite a few slugs, I didn't have the plague of slugs that others reported - and yet I saw slugs roaming in packs elsewhere in the garden.  Use a copper trowel to have a little dig around your beds: If a pile of pearl-like eggs is unearthed a few inches deep in the soil, get rid of them. This is slug spawn.

Petroleum Jelly.  I haven't tried this but have heard that a slick of jelly around the base and top of pots will act as a barrier to slugs and snails.

Mint/Sage/fennel/chives.  Allegedly planting these herbs or adding these to your mulch will deter slugs.  Worth a try.


So there we have it.  Personally, I believe no single method will keep slugs at bay but using several at least gives your plants a fighting chance.  Dare I say though that, as with all creatures in the garden, slugs are an important part of the eco-system so balance is needed.  Good luck!

Slugwatch is a good website for identifying slugs and more information.

28 comments:

  1. Fortunately I don't normally suffer a huge amount of slug damage. I put this down to being ruthless about clearing debris from my garden. I also use blue slug pellets, which I have found to be the surest countermeasure. I didn't know that Leopard slugs eat other slugs, but I do see them in my compost bins, so I will try not to kill them from now on.

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    1. Like you, Mark, I clear debris come spring so that there's less hiding places for slugs. I do squish the babies and I think all this helps to keep the problem under control. Now that I've found out that Leopard slugs are the 'good guys', I keep finding more of these than other slugs. I wonder what they eat if there aren't any other slugs to feast on!

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  2. I've already found lots of slugs in the garden this year. I fear it's going to be the year of the slug with the favourable conditions we've had, a mild and wet winter.

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    1. Oh yes, slugs, aphids, all kinds of nasties lying in wait after the mild start to the year! I've just discovered that plum aphids have colonised my plum tree, so I'll have to get started on aphid control next! Hopefully some of my tips will help with the slug control, Jo!

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  3. Wow, you've done a lot of research! We've favoured the beer traps in the past - we figure at least they die happy. Last year we didn't have as much of a problem though, we think the chickens helped to keep the population down by treating them as a yummy snack!

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    1. I have a confession: I actually started to write this post (and research it) a year ago. Recently found in my drafts, I thought the info was too good to waste so polished it up a bit and went to print! I'd love to keep chickens as part of my slug control armoury and have a feeling that pigeons may help out with that here - with the bonus that it keeps the birds off my veg if they've already demolished the meat course!

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  4. An interesting, and informative post with good links. I do get rid of slugs that I come across on the plot but take few active measures to deter them. Flighty xx

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    1. That's probably a very wise course of action, Flighty, on the basis that we'll never get rid of them all. I do keep an eye out for recently planted veg though so that they get a half decent chance of growing strongly!

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  5. I must admit any slugs I find are dispatched in a bucket of salty water. When I first had the veg beds build I smeared the edges with petroleum jelly, it works very well.

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    1. Ah, good to know, Joanne! I have found some slugs in the raised beds but as they've been there for a few years now, I have a feeling that they're sneaking in underneath. At the moment I'm going for decapitation so that I can carry on with what I'm doing!

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  6. Goodness, the sight of so many slugs has me needing to lie down in a darkened room!!!
    I haven't the heart to kill them but I do search for them and move them. It's awful when you go out and find headless seedlings....that happens to my melon seeds every year!!! I think I'll try the jelly.xxx

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    1. It's a bit gruesome isn't it! Poor slugs, they get such a bad reputation but we gardeners have to protect our hard work! I hear that slugs, like snails, will find their way back to where they came from so moving them is just giving them a bit of exercise - unless you put jelly all round the garden … now there's a thought!

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  7. Is that red one a Liverpool Football Club supporter Caro? I've tried various methods over the years but at home the best one is the nightly patrol with a torch and subsequent disposal. I can't do this at the allotment and this year will be trying a combo of bran/ eggshells round vunerable plantings. Thanks for all the other suggestions.

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    1. Haha! Luckily I've never encountered a bright red or yellow slug in real life - although around here he'd have to be an Arsenal supporter! (Maybe the leopard slugs are secretly supporting Tottenham, with their black and white stripes?) I did a few night patrols last year and was a bit horrified at the ease with which I spotted slugs - the garden was positively slithering!

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  8. I have applied the first lot of nematodes this week. The biggest drawback for me is the expense but if you don't have a huge area to cover it's worth signing up for a two part programme. Apply the first lot in March ideally and the second six weeks later. By the time this second lot gives up the ghost most plants will be growing well and less susceptible to slug damage.

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    1. The first few weeks are definitely the time to be on the alert, rusty. Well done for getting on with the nematode thing, I'm just not organised enough - plus I think I'd need rather a lot of them. As I keep finding Leopard slugs, I wonder if I could box them up and post them out to people - no, probably a bit cruel!

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  9. Good grief, that's a large variety of slugs. The ones that eat egg shells sound terrifying - kind of like eating glass to prove how hard you are. I cut the grass edges round my raised beds yesterday and snipped a few slugs at the same time. Ugh.

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    1. Slicing slugs is gruesome at the time but you quickly adjust and move on! In researching for this post I read that slugs can move over razor blades which puts our egg shell defences to shame. I quite like to remember that for every slug I despatch, that's potentially another 400 that won't be living in my garden! Kind of levels the playing field a bit.

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  10. The small ones are the worst! We also have a very active snail population.. I've used petroleum jelly round pots which does work until plant leaves grow and touch other plants/walls etc and them the slug tightrope or abseil across. I've also put poodle wool around shoots which seems to work 0 apparently human hair works too as the hair sticks to the mucus. I tried out a spray last year that worked but also would work our expensive if you had lots to treat and I also have some Slug Stoppa granules which again work but are expensive.

    Another ploy is to place pots in a plant saucer of water to form a sort of moat -- you can raise the pot out of the water the plant doesn't like to sit in water. Ther problem here is that you have to keep it topped up.

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    1. Hahaha - love the mental image of slugs tightroping or abseiling their way across to juicer feasts! … until I remember that it's all very possible. Eeuuuuw! There's some good suggestions there, Sue. I didn't know about hair stopping them but that makes sense. I guess that's how wool pellets work to stop slugs. I have a hosta that has reappeared after being eaten last year so it needs to be transplanted; I think I'll try your pot and saucer trick - thanks for the tip!

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  11. What an amazing variety of colours they come in!
    I leave the slugs to my birds and hedgehog. The birds are always rooting through the borders and we know the hedgehogs are around by the messages he leaves on the lawn!
    When buying hostas, I usually only buy the ones that have thick leaves and don't have much of a problem with them being eaten, hopefully the birds have eaten all the slugs that are anywhere near them.

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    1. Technicolour slugs are a new one to me Pauline - thank goodness! I wonder where those brightly coloured ones hail from, their colouring wouldn't make for good camouflage in this country! Lucky you having a hedgehog to deal with the problem. I've never seen an urban hedgehog, hopefully they're staying safe in the undergrowth!

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  12. Thank for sharing this great lesson!

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    1. You're welcome, Endah! Hopefully there's some tips here that you can use!

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  13. We get a lot of slugs in our garden, but the large ones seem to confine themselves to eating algae and stuff off the compost heap. We don't do anything to control them, except encourage wildlife into the garden. So far our hostas and vegetable greens have gone unscathed!

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    1. You've made me think now, Firehorse. I'm not sure I know what the slugs in my garden eat - I could be blaming them for the holes in my beans when I should be blaming the pigeons! I suspect there might be plenty of slugs lurking in my compost bin as well! You're certainly very lucky if slugs leave your hostas alone, there must be some very tasty compost and algae in your garden!

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  14. Hmm, I like the idea of a copper trowel, I may have to look in to that, but I am happy to say that so far I have yet to find any slug eggs. Lots of moth pupae though! Those monster red/orange ones. Decapitation sounds about my speed, and as I will soon be planting out the second sowing of broad beans, very necessary I think. Otherwise its a case of taking a deep breath and having plenty of plants in modules to replace the ones lost to the wretches. Though at the moment it is the blackbirds doing the most damage, they have dug out lots of my precious beetroot seedlings as they scuffle around in search of food for the hungry progeny whose demanding chirps accompany my gardening at the moment!

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    1. I just had to look up moth pupae, Janet, to see what they look like. I have to confess that I've been guilty of chucking a few of these away when I find them, not knowing what they were! Whoops. Must bone up on my moths and butterflies. How frustrating to have to fend off blackbirds as well as slugs! I'm not sure how much of a slug deterrent my copper trowel is but it's a lovely tool to handle! It's supposed to put them off the scent and confuse them and also has a nice sharp edge for decapitation, heh heh. Hope you have more success with your second sowing of beans; I was lucky with my broad beans as they've all (but one) germinated and growing very nicely. All my other seedlings are netted off, mostly against cats digging - it's when I plant them out that I start worrying!

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