How much eggshells to use
The amount of eggshells you need to use will vary depending on the size of your plants and the type of soil you have. A good rule of thumb is to use about 1/2 cup of crushed eggshells per plant. You can also add eggshells to the soil when you are planting new plants. To do this, simply crush the eggshells into a fine powder and mix them into the soil.
If you are using eggshells to make a fertilizer tea, you will need about 10-20 eggshells per gallon of water. Let the eggshells steep in the water for 24 hours before straining and watering your plants with the tea.
It is important to note that eggshells can be alkaline, so you may want to avoid using them if you have plants that prefer acidic soil. You can test the acidity of your soil with a pH meter or by using a soil test kit.