Slugs and snails are voracious pests of hostas (Hosta spp.), which thrive in U.S. Department of Agriculture plant hardiness zones 3 through 9. Even as the tips of these shade-loving perennials are emerging from the ground in spring, slugs are ready to feast on them. It takes vigilance to prevent your plants from looking like lace doilies, but most home remedies are only minimally effective. Baits and diatomaceous earth are the most effective slug deterrents, as well as choosing large, thick-leaved hostas that erupt quickly from the ground.
The best bet for preventing slug holes in hostas is to bait the area whenever the ground is moist, especially in early spring and fall. Anticipate slugs and bait before growth begins. Use an organic bait that is not toxic to pets or wildlife. These baits, sold under the brand names Sluggo and Escar-Go, for example, are made from iron phosphate, which breaks down into nitrogen in the soil. Sprinkle the bait lightly around the area every week to 10 days. You won’t see dead slugs, because they crawl away to expire.
Diatomaceous earth is a sharp dust made from crushed fossils. Its sharp edges prevent slugs from crawling over it. Wearing a mask to protect your lungs, apply the dust liberally around the base of hostas. It needs to be reapplied often when washed into the soil by rain or watering.
Some gardeners report success with crushed eggshells, but simply hand-crushing the shells isn’t sufficient. Instead, collect and dry eggshells thoroughly and grind them in blender or food processor to produce a sharp dust. Apply a wide barrier around the base of the hosta. Another method is to hand-pick slugs during wet weather, tossing them into a carton of soapy water.
Rake up plant debris in fall and continue to bait, because slugs reproduce in fall. Consider using drip irrigation so water is delivered to plant roots without keeping the surface soil moist. Keep the area weed-free to reduce hiding places, and remove dead leaves from the ground. Slugs also like to hide under rocks and boards, so check underneath them.
Hostas with thick, quilted leaves are less attractive to slugs and snails. Cultivars include the large, golden-leaved “Sum and Substance” (Hosta “Sum and Substance”), blue-green “Blue Mammoth” (Hosta “Blue Mammoth”) and cup-leaf “Abiqua Drinking Gourd” (Hosta “Abiqua Drinking Gourd”).