06/05/2026
Coffee wakes you up and it might just kill slugs. Linda Brewer, OSU Extension soil scientist, shares that research shows that using a 1% to 2% solution of coffee mixed with water as a soil drench caused 100% of slugs to leave the treated soil and subsequently die of caffeine poisoning. A 2% solution of caffeine applied to the growing medium or orchids killed 95% of orchid snails and gave better control than a liquid metaldehyde product – the common slug bait. To make your own soil drench, add 1 part water to 2 parts strong brewed coffee (1 cup water, 2 cups coffee). To reduce slug feeding on foliage, add 9 parts water to 1 part brewed coffee and apply as a spray. “A sensible approach would be to apply diluted coffee to a sample of leaves and wait for a few hot and sunny days to watch for leaf burn or other damage,” Brewer said. “If there’s no damage, go ahead with spraying.”
Curious about using coffee grounds in the garden? https://today.oregonstate.edu/news/used-appropriately-coffee-grounds-improve-soil-and-kill-slugs
