In the beginning, Marjorie used stones the size of basketballs and larger to frame the beds of her vegetable garden, to hold the dark, crumbly, earthworm-laden soil that now fills each bed to the brim and over the brim. Deep within the cool dark crevices between those stones, caramel-colored slugs sleep away the daylight hours, inches away from the succulent leaves and fruits that furnish their nocturnal feast.
Growing lettuce and strawberries in Marjorie’s garden has been a slug-fest. Last year, the slugs hit hard on the eve of the first ripe strawberries, reminding us that it was time to lay down our defenses, a ring of diatomaceous earth around each bed. We barely won the battle, but the war goes on.
Diatomaceous earth, the fossilized remains of diatoms, hard-shelled algae, is used in swimming pool filters. It is abrasive to the soft bodies of slugs and they will not traverse it. They do have the uncanny ability to find any pathway left uncovered, so you must form a continuous circle between the slugs’ daytime hiding places and the plants you intend to protect. Also, it must be replenished after every rain or irrigation.
In addition to the strawberries, we protect lettuce, spinach and basil plantings, indeed all tender seedlings, with diatomaceous earth. We buy it in bulk from swimming pool supply dealers, typically cheaper by the pound than the smaller quantities sold for garden use.
This year we are adding wood ashes to our arsenal, scattering them inside the rock crevices where we know the enemy is hiding during the day, a one-time application during planting season. Wood ashes from the fireplace or wood stove can be used sparingly (15 pounds or less per 1,000 square feet) in the garden each year, supplying essential potassium and micronutrients. Using larger quantities, however, will raise the pH of garden soil above optimum levels for plant growth.
Perhaps more abrasive than diatomaceous earth, the ashes may make the bed perimeters less inviting daytime shelters for the slugs. Time will tell.
What about beer? Attracted to the yeast, slugs have been known to drown in pools of stale beer placed strategically about the garden in shallow containers with the lip of the container flush with the soil. I tried this recently, sacrificing a bottle of my favorite pale ale, but captured no dead drunks. Perhaps I’ll try a cheaper beer and add a little molasses to the brew.
If you like to wander about the garden before sunrise, try baiting slugs with citrus fruits. Squeeze the juice from several oranges or grapefruits and scatter the halves around the garden before dark, leaving one inside edge close to the ground for easy access. Stroll though the garden before dawn, drinking the juice and picking up the “traps,” and dispose of the slugs by feeding them to your ducks, or otherwise.
Recently, sequestered in the corner of a restaurant banquet room filled with celebrants of a friend’s birthday, a small group of avid gardeners shared slug-control strategies. One member of the group announced she was going to try copper pennies. She had read that copper flashing placed around the garden beds would deter slugs, apparently giving them a mild electrical shock when they tried to cross the barrier. Well, she has a big jar of copper pennies and a hot glue gun.
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