Controlling slugs and snails (part 2)

May 26, 3:42 PMDetroit Organic Gardening ExaminerBill Canaday

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R.J. Reynolds Tobacco Company Slide Set, Bugwood.org

Cultural Control

Step one in controlling slugs is to reduce favorable habitat. To a large extent, this is just ordinary garden hygiene cranked up a notch. A good snail and slug control program relies on a combination of methods. The first step is to eliminate, to the extent possible, all places where snails or slugs can hide during the day. Since slugs require moist soil in which to lay their eggs and cool, moist, sheltered sites in order to hide during the day, try to open up the garden and landscape to more sun and air penetration. Boards, stones, debris, weedy areas around tree trunks, leafy branches growing close to the ground, and dense ground covers such as ivy or beds of mint are ideal sheltering spots. There will be shelters that are not possible to eliminate—e.g., low ledges on fences, the undersides of wooden decks, and water meter boxes. Make a regular practice of trapping and removing snails and slugs in these areas.

As you clear away these safe havens, you make your traps just that much more effective. The snails and slugs still get what they are looking for by way of cool, moist, shelter. But now they are only finding that shelter where it is convenient for you … in your traps.

Often, gardens and plants are over mulched. Especially where there is a slug or snail infestation, mulch should not be applied thicker than three inches and a uniform layer of one inch is desirable. This provides some protection from rapid drying to the plants but does not retain excessive soil moisture. Since mulch seems to disappear faster than it appears, I aim for an initial (loose) layer of about 2-4”, knowing that a good rain or two will pack it down into the 1-3” range.

Since slugs often like wilted or decaying plant material, do not place weed remains, vegetable trimmings or fresh grass clippings in the garden. Place these into a compost pile which is frequently turned for more rapid compost formation at higher temperatures. A hot compost pile will easily reach 170 F. and maintain that temperature for a week or more. Clearly, the heat generated in the compost pile is not 'snail friendly'. Likewise, remove plant remains and leaves in the fall. You will have to evaluate your priorities here, because you will need to weigh the value of applying a late fall mulch to protect the soil against the probability that you are providing shelter for some snails or slugs. I, personally, make protecting the soil my priority but that is because I am willing to accept a less than total victory over the slugs in exchange for richer soil.

Also, locate vegetable gardens or susceptible plants as far away as possible from shelter. Reducing hiding places allows fewer snails and slugs to survive. The survivors congregate in the remaining shelters, where they can more easily be located and removed. Switching from sprinkler irrigation to drip irrigation will reduce humidity and moist surfaces, making the habitat less favorable for these pests. Choose snail-proof plants for areas where snails and slugs are dense. Many plants resist damage from snails and slugs including begonias, California poppy, fuchsias, geraniums, impatiens, lantana, nasturtiums, and purple robe cup flower, and many plants with stiff leaves and highly scented foliage like lavender, rosemary, and sage. Most ornamental woody plants and ornamental grasses are also not seriously affected.

However, judging from the photo above, they seem to like eating tobacco just f

If you design your landscape using plants like these, you are likely to have very limited damage from snails and slugs.