Holidays have a way of dredging up old memories, for example our grandmother's method of putting a dried, crushed eggshell into her garden.
Indeed, recent research has shown that consuming eggshell powder as a dietary supplement increases the formation of both cartilage and bone in people with osteoporosis, and can significantly strengthen bones.
Using Eggshells in the Garden
The calcium from eggshells is also welcome in garden soil, where it moderates soil acidity while providing nutrients for plants. Eggshells contain such an abundance of calcium that they can be used almost like lime, though you would need a lot of eggshells to make a measurable impact. By the time they are well ground, it takes 150 eggshells to make a cup of coarse eggshell powder. You can make precious pulverized eggshells and use them as a dietary supplement for selected plants. Tomatoes that have a handful of eggshell meal worked into the planting site are not likely to develop blossom end rot, and plenty of soil calcium reduces tip burn in cabbage, too.
We might have heard ten thousand times that eggshells placed on the soil's surface deter slugs, but when we tried it the slugs just laughed. When some gardeners set up two actual tests, they found that a ring of eggshells stimulated slug feeding rather than stopping it. It is a myth that eggshells deter slugs.
Yet eggshells are quite useful in adding calcium to homemade fertilizers, or you can simply make calcium water by steeping dried eggshells in water for a couple of days, and then using the strained water for your plants, including houseplants. Plants that haven't been re potted for some time often perk up quickly when given a good drench of eggshell water.
Clean Eggshells are Safe Eggshells
Eggs are known carriers of salmonella, which should not be present on uncracked eggs that have been well washed, but you never know. Unless the only place the eggshells are going is into the compost bucket, you should rinse them well and let them dry in a sunny windowsill.
The dryness should kill any salmonella present, but if you want to store ground eggshells that are safe for you or your dogs to eat (eggshell powder is used as a calcium supplement for dogs, too), sterilize them in a 93°C oven for 30 minutes. You can then pulverize the dried eggshells using a mortar and pestle, or let a coffee grinder do the work for you. Stored in an airtight container, crushed eggshells will probably last forever.