Are eggshells or coffee grounds beneficial for tomatoes?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.Eggshells and coffee grounds give limited benefits to tomatoes when used appropriately. Eggshells provide calcium but decompose over months. Coffee grounds give nitrogen, but should be composted first. Both methods work best as a supplement to a balanced diet, rather than replacing proper soil management.
Eggshells
- Add calcium carbonate to prevent blossom end rot
- Require crushing and months to decompose
- Affect soil minimally due to slow release
Coffee Grounds
- Provide nitrogen for leaf growth when composted
- Fresh grounds acidify soil and stunt roots
- Must mix with brown materials in compost piles
To achieve the best results, handle the eggshells properly. Properly prepared eggshells are washed and sterilized in a 200°F oven for 10 minutes. They are crushed to a powder in a blender or food processor. For planting, add 1/4 cup of crushed eggshells to each planting hole in the fall, allowing several months for the calcium to be released slowly over that time. Use gypsum if necessary for rapid action against current Calcium deficiency.
Before you use coffee grounds for composting, compost them first. Combine fresh grounds with a 1:1 ratio of dried leaves or straw. Turn the pile once a week for about 2-3 months. Finished compost should smell earthy not rancid. Apply about 1 inch to the soil around your plants once a month. This will provide a steady source of nitrogen and will not raise acidity.
Soil testing will identify real needs. My garden soil revealed an adequate level of calcium and a low nitrogen level. The addition of eggshells probably did not work, while the composted coffee grounds were effective. So, be tested in the spring before making any amendments. Balanced 10-10-10 fertilizers can outperform homemade solutions in measurable outcomes.
Make amendments, supplements, and not solutions. [Add eggshells and gypsum for Calcium security] [Add coffee compost and fish emulsion for Nitrogen]. Always maintain the proper pH and water levels. None of these will matter if you have the wrong region or resort to using millions of useless amendments and fail to pay attention to the basics. Again, fundamental elements have greater value to your healthy, productive tomatoes than any one additive.
Read the full article: 8 Common Problems With Tomato Plants and Solutions
