I have to confess that up until this season, my slug awareness had dipped to a very low ebb. The last time I’d had to face down an onslaught of the slimy mollusks must have been in 1976, when I gardened a rich pond-side tract in southern New Hampshire. Since then, my gardening has been decidedly upland: a hillside in New England, a ridgeline in Broad River, a second-floor condo in Asheville.
Slugs? Not on my windowsill. Nary a snail, either. (And pretty much anything one can reasonably blame on a slug applies to their helmeted cousins as well. Except, of course, that snails are more inclined to keep their slime to themselves.)
Oh, sure, I’ve advised friends who’ve been slimed from time to time; I’ve heard complaints. But I haven’t actually dealt with them — or, oh dear, handled them. (There isn’t a dish detergent on the market that will remove the residue. Basically, you have to physically scrape the stuff off your fingers with a rag.)
This year, however, I’m gardening with a friend whose quarter-acreage backs up to a branch. The soil is moist and reasonably rich; the foliage is lush. In short, the slugs are in their element, and they feel fine.
It could be worse. The slugs hereabouts don’t seem to exceed 3 inches or the thickness of a roller-point marker. (In some locales, they grow to 10 inches, and I shudder to imagine how much plant material such a Loch Mess Monster could consume in one sliming.) According to slug authorities, these greasy critters are far more of a problem in the western United States, where some farmers rank them numero uno among crop invaders. But ours still manage to do ample damage.
Creatures of the moist gloom, slugs feed primarily from two hours after sunset until two hours before sunrise. Intentionally or not, this dining schedule is a good bet for eluding most gardeners, who are thus more likely to detect the sluggish presence via the big, ragged holes left in leaves, fruits and stems. These terrestrial creatures generally work their way up — so the damage first appears lower down. The remaining foliage will usually have slime trails where the slow foe hath slid.
Plants that suit slugs’ catholic palates include artichoke, asparagus, basil, beans, brassicas, celeriac, celery, chard, cucumber, eggplant, greens, iris, lettuce, onion, pea, pepper (seedlings), sage, squash, strawberry and most fruit trees.
If you go slug hunting first thing on a cool morning, you may find some of their number still upstalk. Hand-picking works just fine, though you will confront the aforementioned slime-removal problem. Be careful not to drop them, as they seem to almost instantly disappear when they hit the ground. Forceps or tweezers would work in a pinch (sorry) but are apt to become clogged with the gooey residue.
Because slugs and snails need to stay moist through the heat of the day, they are likely to be found underneath things once the sun has lifted head from cloudy pillow.
This leads to the cardinal rule of slug disestablishment: Don’t provide these squirmy, foliar terrorists with caves. In other words, clean, clean, clean. If you’re a mega-mulch aficionado who revels in laying down 10 inches of hay or dry leaves between your plants, this will offend every fiber of your being. But there it is: You must deny the enemy cover.
Since slugs treasure wetness and the essential function of mulch is to prevent moisture loss, perhaps you could simply hold off until the plants are larger and the ground is drier before applying the topcoat. (Like, maybe, July.)
Clear away leaves, bricks, flat rocks, branches and other material that might prove to be inviting locales for slug siestas.
To further inhibit the slippery assault, mulch with crushed rock, cinders, crushed eggshells or sharp sand. Such rough substrates, which irritate slugs’ crawly parts, tend to divert them to softer parts of your yard.
You can address the moisture issue by watering in the morning instead of at night. Tests by Swiss agronomists have shown that this simple trick reduces slug damage on lettuce crops by 80 percent, according to writer Tanya L.K. Denckla. Her book, The Gardener’s A-Z Guide to Growing Organic Food (Storey Publishing, 2003), is the best such reference I have found in 35 years of gardening.
But if the gooey gang continues its invasion, the time has come to set traps (sorry, PETA, but war is hell.)
You could go out in the pre-dawn hours, prop a small cardboard box on a twig, tie a string to the stick and sit in a lawn chair with a flashlight — poised to drop the box on your prey. But I prefer to dig a hole and insert a tin can or nonrecyclable plastic container with its lip almost flush with the surface. Bait the trap with some banana peel or beer (the banana will draw more slugs, but the beer will drown them — take your choice). To shade the container, make a lean-to using a scrap of board with one edge resting on the ground and the other propped up by a pebble to permit easy entrance. (As far as that goes, the board alone will attract some shade seekers — the bait just turns it into a better slug trap.)
My preference is catching them alive, but then I’m a soft touch, figuring that every creature has a rightful place within the ecosystem, even if it’s not in my garden (and besides, I have better uses for beer). If you do the same, be sure to take your captives a long way from the garden before setting them free: They’re small but persistent.
Once the summer sun has deeply warmed the soil (75 degrees at the surface) and the season has turned drier, slugs tend to steer clear of sunny places altogether. And mature plants generally suffer less damage anyway, having tougher stems and bottom leaves. So when dry conditions begin to cry out for mulch, you can pretty safely dress the garden. Still, if your location (like mine) is near a stream, it might be a good idea to leave a bare stretch along the margins to discourage emigration from surrounding fallow soil.
For those who prefer sprays, there are several organic concoctions that are said to be effective against slugs. Garlic powder and raw garlic contain allicin (which is toxic to slugs), and wormwood is a repellent (make a tea using either of these and spray liberally). A spray composed of two parts vinegar to one part water is also reputed to keep slugs at bay. (This is quite acidic, though, and may burn tender plants.) And very strong coffee (i.e., a 1 percent caffeine solution — a regular cup of instant coffee runs .05 percent caffeine) will kill them outright. In lower doses, caffeine reportedly curbs their appetite.
Iron phosphate, the active ingredient in Sluggo and Escar-Go!, is reportedly nontoxic to birds, mammals and plants, but fatal for slugs and snails. It is considered to be an organic product.
If flowers are your thing and slugs are taking the bloom off your passion, slugs tend to turn up their noses (noses?) at the following species: achillea, ageratum, arabis, armeria, aster, astilbe, calendula, campanula, cosmos, dianthus, dicentra, eschscholzia, galium, hemerocallis, iberis, kniphofia, lobelia, mentha, nasturtium, paconia, penstemon, phlox, portulaca, potentilla, ranunculus, rudbeckia, saxifrage, sedum, thymus, verbena, vinca, viola and zinnia.
Marigolds, though repellent to many other pests, seem to constitute a favorite salad green of these voracious slime balls.
The lesson? You can wade into a slugfest and live to garden another day.
But I still haven’t figured out how to clean those rags.