Crushed oyster shells

An excellent source of calcium, these shells are a must for the veggie garden. They are also known to sweeten the soil (i.e., increase the pH), improve drainage, help keep slugs away and increase organic matter. Smashed oyster shells are particularly useful when planting squash, tomatoes, lavender or lilacs. Simply crush the dry shells with a hammer or brick (be sure to use safety glasses and gloves).

- Garden Wise (link here)

I might have to try this. I can get a 50-pound bag of crushed oyster shells at the local farm supply store for about $10.