Using eggshells in gardening is nothing new. I remember my mother saving eggshells, coffee grounds and teabags for adding to gardens and flowerbeds in true fashion of someone raised during the Great Depression. And I’m sure her mother before her did the same on their pioneer North Dakota homestead, in their ‘waste not, want not’ style.
Eggshells have been shown to add mineral benefits to some soils, and the gritty texture of pulverized shells might loosen heavy clay soil somewhat. And eggshells can be added to compost. There are some anecdotal stories of eggshells possibly deterring rabbits and deer, as they tend to shy away from items that are protein-related, as part of their herbivore nature. Many successful repellents contain egg substances as an ingredient, although dried eggshells probably have little of the repellent property remaining, still it’s a no-cost chance.
But I think one of the greatest uses of eggshells is in slug control, which are a serious problem in many flowerbeds and gardens, especially in shaded, moist sites. Eggshells can be stockpiled now for later use.
How to use eggshells for slug control:
- Eggshells are most effective if used in quantity, so stockpiling during winter and spring is a good idea.
- To save eggshells for later use, they are best rinsed in water immediately after using eggs in recipes, to wash away the slippery coating inside the empty shell.
- Allow shells to dry completely, then crumble them into a container for storage. If eggshells have been properly rinsed and dried, they won’t develop an odor.
- Crumble eggshells into small pieces, approximately pea-size or smaller.
- Slugs are known to be deterred by sharp, gritty material placed on the soil surface, making it difficult for them to crawl across with their slimy bodies. Crumbled eggshells, with their sharp edges, have proved successful for many gardeners in controlling slugs.
- Place a ring of crushed eggshells around each plant on the soil surface in a thin layer, covering the soil in a 3 or 4-inch wide band.
- Perennial hosta, which are a slug-magnet, are easier to protect if the eggshell band is placed before the hosta emerge fully in spring. After the leaves have fully expanded, it’s more difficult to get under hosta plants.
- If wood mulch is used around perennials, slugs can hide under the mulch, traveling underneath the mulch, making an eggshell band on top of wood mulch less effective. If mulch is used, it’s best to brush aside the material about 4 inches away from the plant’s base, and use a thicker layer of eggshells to serve as mulch in the circle closest to plants, or mix the eggshells into the wood mulch, so slugs can’t crawl over or under without contacting sharp shell edges.
- Crushed eggshell circles help deter slugs in perennial beds, annual flowers, and around vegetables, such as cabbage, cauliflower and broccoli, whose smooth leaves are slug-targets.
I might add that reports of success with eggshells do vary. If the eggshells mat themselves together, losing the sharpness, they’ll lose their effectiveness. Even university recommendations vary, some recommending them as highly successful, others indicating less success. Even store-bought slug baits aren’t 100% effective. Personally, I’ve had success with eggshells. Either way, they’re inexpensive and well worth using.