A few fast tips can help deal with slugs

A slug munching on a cabbage plant.
A slug munching on a cabbage plant.
Photo by Jessica Walliser
| Friday, May 17, 2013, 6:54 p.m.

I think you'd be hard pressed to find a gardener who, at some point or another, hasn't been plagued by slugs. These members of the mollusk family are herbivores that greatly enjoy nibbling tender seedlings, hostas, tomatoes and lots of other common garden plants.

Slugs are particularly problematic during wet periods and in shaded gardens. They are most active at night and on cloudy, rainy days. If you are finding tattered holes in plant leaves but can't figure out who the culprit is, head out to the garden after dark with a flashlight in tow, and look for the slimy little guys or the silvery trails they leave behind.

Slugs are hermaphroditic, meaning each one has both male and female reproductive organs, so every one of them can lay hundreds of eggs a year. They cannot, however, mate with themselves — they need a partner for fertilization. If you have a regular slug problem, the trick is to maintain a control program from early spring all the way through fall in order to keep a tight rein on their population.

First and foremost, look to preventative techniques for controlling slugs. In areas where there is a history of slug damage, avoid using loose mulching materials. Straw, hay, pine bark and shredded hardwood serve as a great hiding place for adult slugs, in addition to being the perfect shelter for egg laying. Use compost, mushroom manure, or leaf mold to mulch those areas instead.

Another preventative technique is to surround the base of susceptible plants with a collar of copper. Slugs experience a mild electric shock when they come in contact with copper, so they avoid it. This technique is a lot of work, though, if you are talking about dozens of hosta or zinnia, but it does work. If you garden using raised beds, simply make a copper “moat” around the entire bed to keep the slugs out.

While trapping slugs in beer is useful, it's also really gross. You have to empty the traps daily to avoid having a festering mess. The slugs are attracted to the yeast and then fall in and drown. Shallow saucers of beer are sunk in to ground level to allow easy access to the slugs. Surprisingly, the slugs don't fall in because they get drunk — in fact some studies show that non-alcoholic beer works even better than regular beer does.

But, by far, my favorite method of slug control is to poison them using a bait. Not just any bait will do, though, since some baits are poisonous to other critters as well. Avoid using traditional slug and snail baits containing metaldehyde or methiocarb as their active ingredient. Metaldehyde is extremely toxic to pets — as little as a teaspoon can kill a cat — and methiocarb is poisonous to many insects and earthworms.

Turn instead to baits using iron phosphate as their active ingredient (brand names include Sluggo, Escar-Go, and others). These baits are not toxic to pets and wildlife, are safe to use around kids and eventually, if they aren't eaten by slugs, will break down to iron and phosphorus — two essential plant nutrients. The baits are sprinkled on the soil surface around plants, the slugs consume the bait, stop feeding immediately and die within a few days.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.

Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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