People frequently ask me what they can do in their organic garden about slugs and snails.  In my garden, I use a multi-pronged approach.  I use the following techniques in combination — I rarely use just one.

• hand-picking
• trapping
• physical barriers
• predators
• ecosystem management

Hand Picking

I pay a “bounty” on each snail.  I pay my kids 1 cent ($.01) per snail if they can hit the yellow line in the center of the busy road next to our property.  Alternatively, they can fill an old plastic bag with the nasty creatures.  My darling daughter specializes in “snail soup” which is a saltwater bath — the snails foam green goo (do not do this in fine china …).  I pay double for slugs because they’re so yucky to pick up.

This program worked really well until the day I told the story and my across-the-street neighbor overheard.  “What!?” he exclaimed.  “I’ll throw them back!”

Trapping

Snails and slugs can be trapped in several different ways.  The most well-known is the saucer of beer.  Actually, use an old bottle top (think: applesauce jar) because you’ll want to dispose of it afterward!  The snails are attracted to the beer, they climb in to feast, and they drown.

I recommend that you keep your pets away from it — our dog loves to drink the saucerfull, and then he barfs snail parts, which isn’t too wonderful.

I have found that my snails are a bit picky — they prefer fresh beer over stale.  You can also mix bakers yeast with water and achieve pretty much the same results.

Another method for trapping snails is watering your garden in the evening, and then placing out lightly rolled damp newspapers.  Junk mail is perfect.  At the end of their nighttime forray, the snails and slugs crawl inside to hide from the daylight.  You simply pick up the paper and throw it away.  (crush the snails first, or they might crawl out of the trash can).

You can also use 1 gallon nursery flowerpots.  Again, water your garden in the evening.  Moisten the pots too, then lay them on their sides in your garden.  The snails will crawl inside.  Pick the trap up in the morning.  Let me know what you decide to do with all the snails …

Physical barriers

Snails won’t cross copper.  Apparently they get some sort of an electrical charge when they crawl across it.  Garden centers sell wide copper strips you can use to circle your plants.  (Bountiful Gardens sells it mail-order).  I have found that the copper becomes more durable if you mount it onto something.  I cut the bottoms off 32oz yogurt tubs or 5gallon nursery flowerpots and staple the copper strips onto the plastic ring. This type of arrangement seems to last several growing seasons.  You press the plastic ring into the soil, plant your plant inside it, and the copper barrier is firmly in place.

Someone at one of my garden classes mentioned putting pennies on duct tape.  I haven’t tried it, but it might be a readily-available source of copper.

I used to have snails climbing my dwarf tangerine trees and eating all the new growth, until I learned that copper can also be used on trees.  Cut a copper strip slightly bigger than the tree trunk diameter.  Use a paper clip to secure the overlap.  (By joining it with a paper clip you won’t strangle your tree.)

Other barriers snails might not cross include crushed eggshells, or diatomaceous earth.  You make a ring of the eggshells or DE on the soil around the plant.  I have had marginal results with eggshells, but my sister swears by them for her artichokes.

Diatomaceous earth is fossilized algae (thank you Wikipedia) which is very sharp to crawling mollusks.  You can buy it by the bag through organic nursery suppliers (Bountiful Gardens will sell mail-order).  DE must be reapplied after you water or after it rains.  I hesitate to use it in great quantity because I wonder what it might do to earthworms and other soft, crawling soil life.  I do use DE in small quantities at the stems of seedlings which are under attack from mollusks or cutworms.

Predators

Decollate snails are predator snails.  They’re small, pointy-looking snails and they eat the round brown snails.  The directions on the container say to water your garden at evening, and then distribute the decollates.  They’re in hibernation in the shipping container, but will wake up when they’re in the moist environment.

The first time I put decollates in my garden, I woke up the next morning, got my coffee, and looked out at my garden.  Something just wasn’t right — I shook my head in effort to clear the sleep.  All around my garden, everywhere I looked, at about the 4foot level — on walls, shed, shrubs — there were brown round snails running for their lives.  Clearly the decollates had an impact!

I’ve reapplied decollates each spring.  I’m not sure that they thrive and reproduce in my garden as readilly as the brown rounds, but I do not find many empty (dead) decollate shells, so they must be out there.  Apparently they hide really well during the day.

Note that if you use decollates, you have to be careful what other methods you’re using in combination.  You don’t want to be killing the decollates.

Other mollusk predators include ducks and chickens, but since I have no experience in this realm, I’ll just mention them and move on.

Ecosystem management

As you consider your snail problem, consider what other elements you have in your garden.  Do you have thick bladed plants like clivia or agapanthus where mollusks love to hide?  Do you have cupped stepping stones, or other ideal hiding places?  Perhaps some changes in design would reduce your snail problem.

How much do you water your garden?  Don’t overwater your garden — it saves water plus it’s better for your plants.  Do the finger test:  burrow down 1inch into the soil.  If the soil is moist, your plants don’t need water.  When you water, water the soil, not your plants.  It’s better for your plants (diseases, etc) plus you won’t provide a nice moist surface for snails.

I notice that I get a “snail influence” coming from the neighbor on one side who has a high-water consumption garden (lawn, begonias, impatiens).  When I changed my garden at that edge of my property to a lower-water garden, with sharp bark chips as mulch, I found I had a lot less snails.

About mulch, here in Southern California it is essential to maintain soil moisture.  However, don’t crowd a thick mulch all the way up to your plant stems.  It invites mollusks, plus it can harbor other pests and plant diseases.  Leave a little space near the stem.

Management versus annihilation

In the chem-gardening world, we are taught: see a pest, grab a product.  In the organic gardening world, we learn that all the life forms work together at some level of balance.  We aren’t striving for 100% annihilation of the pest species; we’re just looking to keep them within reasonable bounds.

Snail and slug control fits into this ethos too.  The goal is to bring the snail population within balance, so that there are some vegetables left over for you.  Yes, they might still occasionally take a nibble of your prized ruby stemmed chard, but hopefully as you try these techniques you will find that you can now grow sufficient chard for both you and a few wildlife.