Answer: Coffee grounds are an excellent source of nitrogen, and will acidify soil to a small degree. You can compost them or you can just broadcast them onto the soil. Either way, they're beneficial to garden soil, and will attract red worms, which will help break down organic matter. As for repelling slugs, the jury is still out. Slugs do not like to travel over rough surfaces so if the coffee grounds are dry, they may avoid the area. If you have a slug problem in your veggie garden you might want to try trapping them rather than using chemicals. I've had good success with both of the following:
Take a terra cotta container and soak it in water so it's saturated. Set the pot upside down near your veggie plants and prop up one side of the rim with a few small stones. Slugs will gather on the inside of the pot in the late evening and early morning. Simply scrape them out and reset the trap. If your garden is large, upend several terra cotta pots. Be sure to empty them regularly!
Or, do the same thing with grapefruit rinds. They love feeding on the insides of these and will make a bee line for them.
Best wishes with your veggie garden!
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