Why might eggshells be good for the garden?
Instead of adding lime to your garden, add eggshells. Eggshells are 93 percent calcium carbonate. Calcium makes plant cell walls stronger. Roots suck it up during growth. Eggshells also contain a bit of nitrogen and trace elements such as magnesium, phosphorus, boron, copper, iron, manganese, molybdenum, sulfur, silicon and zinc. They might also be a great substitute for rock dust. Eggshells are free and a lot lighter than crushed rock!
In heavy downpours, naturally occurring calcium tends to leach away. Eggshells could replenish some of it back.
Where do I find eggshells?
Keep shells in the refrigerator until all your eggs are used up. Ask your neighbors to save theirs for you too.
Which plants may benefit from eggshells?
Calcium will help prevent pale-colored leaves on beans, brown leaf tips on cabbage and kohlrabi, and blossom end rot on tomatoes, peppers and eggplant.
Combine eggshells with…
To mimic dolomitic lime, combine Epsom salt with eggshells. Dolomitic lime contains 4 percent calcium carbonate and 38 percent magnesium carbonate. See the recipes for Epsom salt coming up next.
Eggshells keep my worm food from getting to mushy. I pulverize them in my food processor along with melon rinds, greens, coffee and tea.
Worm castings (for trace minerals) and alfalfa pellets (for nitrogen) work well for me in planting holes along with eggshells.
Prepare a Planting Hole or Bed with Eggshells
Wash the shells (boiling will kill pathogens but I don’t bother unless I’m using at school). Air-dry to make them easier to crush. Smash or pulverize into a fine powder. Work the pieces into the soil around the planting hole. Eggshells are 90 percent water soluble so it makes sense to keep your soil moist.
I know from experience that eggshells can take years to decompose if left whole in the garden on top of the soil. I’ve found that if I dry and crush them first, and cover with some soil, they decompose faster and work better in my planting holes too.
Eggshells Soil Drench Recipe
I also soak eggshells in water for a day or two and use that water on plants that tend to respond to extra calcium such as tomatoes and peppers.
After making hard-boiled eggs, I use the leftover water as a soil drench around my plants, especially brassicas such as kale and kohlrabi. I use about 3 cups for every plant and again I usually water the plants first before I apply.
Eggshells Quick Tips
- Save your washed eggshells in a plastic bag or egg carton in the refrigerator and wait until you have a large amount before crushing. Use the bottom of a cup or rolling pin to crush.
- Some folks bake their eggshells to remove moisture, kill any potential salmonella and to make them more brittle for crushing. Heating at temperature above 160 degrees Fahrenheit will kill salmonella. Freezing does not kill all salmonella.
- Keep eggshells in a bag if young children want to help you crush them. This keeps any residue off hands and protects them from cuts. I always had my kids wear gloves just in case the bag breaks.