Effects Of Eggshells On Tomato Plant Growth And Garden Soil

Have you been throwing away the empty eggshells after making an omelet or another egg-based dish? It is high time you stopped this habit as eggshells have myriad benefits to a wide variety of plants and the environment.

Egg is the most nutritious food on earth as it contains all essential and trace elements needed for healthy growth and physiological development. Eggshell is a rich source of calcium; it consists of 93-96% calcium carbonate and other trace elements. This makes this “waste” fit to supplement or supply calcium when needed.


Plants require several elements and minerals to grow optimally and perform up to their genetic potential. Nitrogen, Phosphorus, and Potassium are macronutrients, and the most essential elements needed by plants in large quantities. Calcium, alongside Iron, Zinc, Manganese, Magnesium, Sulfur, etc is considered as a micronutrient. Nitrogen, Phosphorus, and Potassium are very important for most plants, Calcium is even more important for some plants, such as tomatoes, pepper, and other vegetables.

Plants require calcium in relatively good quantity but not as much as the Nitrogen, Phosphorus, and Potassium. The importance of calcium in plant growth cannot be overemphasized. Primarily, calcium helps to strengthen the cell wall of plants making the plants vigorous and firm to resist any form damage. In addition, calcium helps to maintain chemical balance in the soil by reducing soil salinity and improving water penetration for better usage of plants.

Eggshell has lots of benefits to the plant, soil, and environment at large; hence, it should not be regarded as waste.  

Benefits Of Eggshells To Plants

Plants are the most beneficial of the benefits of eggshells. Primarily, eggshell supply calcium, which can help to strengthen the plant’s cell wall and prevent the occurrence of some plant diseases and infections. Plants that benefit from eggshell mostly aside from the macronutrients are Tomato, Cabbage, Lettuce, Carrot, Celery, Pepper, and other vegetable crops.

Blossom end rot in tomato plants

The deficiency of calcium in the soil can lead to several growth disorders in these vegetables. Such as; tip burns in cabbage and lettuce, blossom end rot in tomato and pepper, cavity spot in carrot, stunted growth in celery, and all plants generally. When the cell wall of plants is weak, the plant becomes weak and tender, reducing its growth rate and increasing its susceptibility to plant diseases.

Calcium, which is found in eggshells, can be used to correct the deficiency of blossom end rot in tomato and other related disorders in vegetable crops. It is cheap, especially when you operate an integrated farm where you have laying birds.  The eggshells can be crushed and used to supplement the calcium content of the soil for better growth of these vegetables and other plants.

Several research works have been carried out on the use of eggshells for plant growth. A research result presented by Anna D. de la Rosa  at California State Science Fair showed the tremendous effect of eggshell on the growth of tomato plants at various levels of inclusion.  

According to the report, the tomato plants were raised in groups of five pots; each pot having the same amount of soil. Three tomato seeds were planted in each of the pots and each group had different amounts of eggshell mixed in with the soil: no eggshell (control), 1 gram, 5 grams, 10 grams, and 15 grams. As they grew, all management operations such as watering were carried out equally on all the treatments; data on morphological changes were measured and recorded every two days for two weeks.

The results showed that the plants with 1 gram and 5 grams grew taller than those without eggshells, the plant with 5 grams ended up being the tallest at the end of two weeks. However, the tomato plants in which the inclusion levels were 10 and 15 grams did not grow up to the 5 grams plant. This led to the conclusion that too much eggshell (10 and 15 grams) does not make the plant grow faster.  A small amount of eggshell is enough to enhance plant growth. This study just affirmed the fact that calcium is a microelement but highly essential for plant growth.

Another study on the effects of the eggshell extract on tomato growth in Muscat showed that eggshell extract has a positive influence on the growth of tomato plants as it increases its length and the number of branches and leaves.  

Benefits Of Eggshell To The Soil

You know, the soil itself is an ecosystem that is made up of a lot of entities to make it fit for planting. Lots of biochemical reactions take place within the soil; these activities usually determine the soil status and properties.

The soil ph is very important in agriculture; most plants thrive best or let me say plants prefer a soil with a neutral ph, a soil that is neither acidic nor alkaline. The Soil ph status can only be known by soil ph testing; the result from this test determines which plant to grow or the soil amendment practice (liming) to deploy.

Eggshell can be used as a liming agent; the calcium from eggshells can be used in garden soil, where it moderates soil acidity while providing nutrients for plants. Eggshells contain a large amount of calcium carbonate, which can be used to correct or adjust the soil ph value from being acidic to neutral, acceptable to grow most plants.  

Other Uses Of Eggshell In Gardening

Gardeners also have creative ways of using eggshells in the garden. Of course, the primary aim is to improve the productivity of the garden at a low cost. Eggshells can also be used in the following ways in a garden.

#1. Eggshells For Raising Seeds

Eggshells can be used as starter pots where seedlings are raised before transplanting to the main field for the continuation of growth. The need to raise healthy seedlings in an intensive environment has made gardeners creatively use eggshells to raise seedlings.  

Eggshell as starter pot
Eggshell as starter pot
Source: Little Scholars Early Development Center

To get started, you need eggshells that were carefully cracked such that only the top is opened. Fill in the eggshell with moist soil or compost to fortify the growing medium. Place one or two seeds inside the eggshell and manage properly by watering daily if needed to enable them to germinate. This is a cheap and sustainable way to raise healthy seedlings for transplant to enable better yield.

#2. Eggshell As Snail And Slug Repellant

Lots of speculations have been aired concerning the ability of coarsely crushed eggshells to repel snails and slugs from cabbage and other vegetables by applying it surrounds the plants to create a border or lining.

eggshells as slug and snail repellant
Eggshells as snail and slug repellant.
Source: Growing GREEN Thumbs

The notion is, the sharp edges of the coarsely crushed eggshells deter the movement of snails and slugs by irritating their skins as they attempt to cross the eggshells towards the plants. However, this technique or claim was refuted by this online resource I discovered during the cause of my research.

#3. Eggshells As Mulch

 Another important role of crushed eggshell in the garden is being used as mulch. The primary function of mulch is to cover the soil surface thereby controlling the soil temperature, conserving soil moisture, and adding nutrients to the soil when decomposed.

Eggshell is biodegradable; hence, it can serve all these purposes. However, the quantity of crushed eggshells required to fulfill this purpose makes it unrealistic to achieve. Sawdust, wood shavings, etc. are other mulches you can use in the garden that would also perform the function of mulching effectively.

#4. Crushed Eggshells As Organic Fertilizer

Eggshell is a rich and cheap source of calcium, which is highly needed by garden crops for better growth and yield. Adding crushed eggshells to the soil on which tomato, cabbage, carrot, and or lettuce is grown greatly helps to supply enough calcium to correct growth disorders or diseases such as Blossom end rot in a tomato plant and other vegetable plants.

In addition, eggshell extract can also be used as foliar fertilizer for garden plants like tomato. Simply place a finely crushed eggshell powder into a sprayer and fill it up. Allow it to settle for several days and use the liquid to water plants, such as vegetables and shrubs. This is a natural fertilizer made from eggshells.

The quest to farm sustainably has spurred the need to creatively make use of the waste in an industry (poultry) in crop production. Eggshells can be cheaply sourced yet they can supply an essential nutrient needed by plants for good growth and amend the soil by correcting the soil ph to make the soil a better medium for plant growth.

Again, nothing is a waste in agriculture. We need to find ways to make use of wastes from other agricultural industries to the benefit of food production.

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