|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.