Home > Blog > Zero waste

Gardening 101: Eggshells as Fertilizer

Gardening is generally seen as an expensive hobby. In order to beautify a garden, one must spend for materials and tools solely for gardening. Though vegetables and fruit-bearing trees may be costly to maintain, one can strategize and be innovative to keep expenses low.   

Fertilizers contribute to the growth of plants. Organic fertilizers, in particular, have been proven to enhance crop yield and soil properties, and prevent pests and diseases. A study further concludes that in a tropical environment, organic fertilizers give these benefits:

  • enhance soil fertility, plant growth and yield
  • enhance water movement into the soil 
  • encourage microbe growth, making soil easier to work with
  • promote farming sustainability

For many years, people have been focusing on using manure as a form of organic fertilizer. If you search the internet about the most used organic fertilizer, it will show cow manure. However, according to a University of Oxford study, organic fertilizers such as manure is a contributor to climate change, biodiversity loss, soil degradation, and water pollution. 

So, how can you use organic fertilizers in your own garden? Most people think of eggshells as trash or material for arts and crafts, but you can also use them to enrich your soil.


Photo by Jobie Grado


Eggshells as fertilizers

Eggshell is an organic fertilizer that has microelements needed by plants to grow well. It helps in developing resistance from factors that could cause stress in plants, particularly when exposed to direct heat from the sun and heavy rains. 

Ernie Lito Bollosa, a licensed agriculturist at the Bureau of Plant Industry, explained in Filipino, “Eggshells also prevent fungal disease in plants, and strengthen plants’ cell walls,  allowing vegetables and plants to thrive in a healthy way.” He also noted that the use of eggshells as fertilizer has been found to be more effective in vegetables, ornamentals, herbs and spices, and other shallow-rooted plants. 

However, eggshells are not recommended for deep-rooted plants. “Deep-rooted plants like fruits need high concentrations of calcium.” Bollosa added that no study has yet been conducted on the ability of eggshells to protect plants from pests.

Despite the proven effectiveness of eggshells as fertilizer, the use of it has some downsides. Eggshells require time for their nutrients to be consumed by plants. The common practice of converting them to fertilizer involves washing the shells, crushing them into small pieces and mixing them with the soil.  But to make them more efficient fertilizers, try adding about 10 to 20 eggshells in a gallon of boiling water. This separates the shells’ calcium content from other components not beneficial to plants. Let the shells soak in the water overnight, and pour the boiled water onto the soil with plants.

Calcium from eggshells can neutralize the acidy of the soil, making it more suitable for planting. Meanwhile, the placing of ground eggshells helps in lessening the solidity of the soil, resulting in spaces where air and water an enter. 


Kitchen scraps as homemade fertilizers

What we consider trash can be repurposed. Here are some examples:


Bones of pork, chicken and cow

Nutrient: calcium

How to turn them into fertilizer: Crush and dry bones under the sun. Apply as fertilizer by mixing them with the soil.


Fruit and vegetable peel

Nutrients: potassium and nitrogen phosphorus

How to turn them into fertilizer: Directly mixing them with soil is acceptable, but it will be more effective if you boil them first. Boil for 10 – 20minutes to extract all nutrients needed. Pour water onto the soil.


Water used in cleaning rice

Nutrient: lactic acid

How to turn it into fertilizer: Simply use it in watering plants.


Water used in cleaning fish

Nutrient: amino acids 

How to turn it into fertilizer: Simply use it in watering plants.


With the world facing various problems such as poverty, pollution, and food shortage, it is good to practice a zero-waste-lifestyle. What we perceive as waste still has significant value. Through recycling and reusing, we can lessen environmental problems and discover new ways of putting food on our tables.