How to defend your garden against invading snails
Annie Mulligan / For The Herald
A snail travels along a leaf in an Everett garden on Wednesday.
Annie Mulligan / For The Herald
A snail climbs up the stalk of a flower in an Everett garden on Wednesday.
European brown garden snails were probably stowaways, and now they're thriving in the Northwest.
Snails are becoming more prevalent in Northwest gardens. Like slugs, their slime-laden buddies, these creatures can do a lot of damage to plants.
Now is the time to do something about snails before they get out of hand, said Sharon Collman, a WSU Snohomish County Extension educator and entomologist.
In particular, gardeners are seeing higher numbers of the European brown garden snail, which has been found around Western Washington for a few decades but appears to be increasing in numbers. Like many pests, people don't tend to notice until there's a large population spike.
There have always been tiny little native snails around the Northwest. The European brown garden snails are larger, about the size of a quarter. The extension office also is getting reports of another snail that's yellow with black stripes.
Non-native snails likely hitchhiked their way here by crawling onto pallets, and then getting shrink-wrapped and shipped along with the imports, she said.
In large numbers, snails can strip most of the foliage off plants, especially those with soft, green, fleshy leaves. On a visit once to Port Townsend, Collman said she saw an entire hill of Jupiter's beard defoliated by snails. The snail poop was so thick she could scoop up a handful.
That said, gardeners shouldn't be overly alarmed, she added. This is just one more pest they'll have to deal with. Fall is about the time snails and slugs start laying eggs so don't delay.
Snails are typically found in shady areas, such as the underside of leaves. They can be found in the sun too. They might occasionally congregate on the sidewalk. Sometimes their empty shells can be found around the yard, leftovers from a bird snack.
Snails tend to chew uneven holes in the center of the leaf, rather than the edge. There may be a bit of slime but not as much as slugs produce. The damaged area can be as large as several times the size of the snail.
Gardeners can try products with an active ingredient of iron phosphate, sold under name brands such as Sluggo. The product should be effective on slug and snails. Look for that on the label. Make sure the product is safe to use around whatever part of the yard is being treated.
Probably more effective and cheaper is simply handpicking the snails and stomping them, she said. If you can't stomach squashing them, put them in a bag in the freezer for a few hours.
Collman also suggested wetting down a portion of the yard now while it's still dry and coming back at night to harvest snails attracted to the moistness. Do that in areas that show heavy snail damage.
For more information, call the Snohomish County master gardener hotline at 425-357-6010. The extension office also offers information for homeowners on how to deal with garden pests online at http://pep.wsu.edu/hortsense.