DIY Fertilizer: Are Coffee Grounds Good for Tomato Plants?

Is everyone in your family using coffee and disposing of the used coffee grounds in the garbage? Something positive can come out of collecting the grounds. They are high in nitrogen and can be reused as a fertilizer in your tomato garden. Its smell can also deter some pests from destroying your plants.

Coffee grounds contain nitrogen, phosphorus, potassium, magnesium, and copper. These nutrients are ideal for the healthy growth of a tomato plant. The grounds also improve drainage, aeration, and water retention when incorporated into the soil. Its pH of 6.8 also favors acid-loving plants like tomatoes. 

Are Coffee Grounds Good for Tomato Plants?

A short answer to the above question is yes. Coffee grounds contain numerous nutrients that are ideal for the growth of a healthy plant. It also improves the condition of the soil by enhancing its drainage, aeration, and the ability to hold water. 

Coffee grounds can be beneficial to your plants and soil in the following ways:

1. Increases nutrients in the soil

Coffee grounds contain a considerable amount of nitrogen, phosphorus, magnesium, and copper. These nutrients help to promote a healthy foliage, development of roots, flowering, and development of fruits on a tomato plant.

Studies have shown that a balanced tomato plant fertilizer can be supplemented with coffee grounds to get high yields. Coffee grounds can be used when the plant is near flowering. They slowly release nitrogen in small amounts, which is very useful during flowing.

2. Improves oil aeration

Using coffee grounds as a fertilizer also increases the amount of organic matter in the soil. This attracts earthworms and other microorganisms, which improves soil aeration. Earthworms help in creating tiny tunnels into the soil that allow air to circulate freely. 

3. Improves the drainage of the soil

Coffee grounds add organic material to the soil that helps to improve the drainage. Tomato plants thrive well in soil that has good drainage. Poor drainage means that the soil is either retaining a lot of water or losing water easily through percolation. 

Tomato plants are likely to develop fungal infection when planted in an area that has poor drainage. Fungi thrive well in an area that is warm and damp. 

4. Can be used to increase the acidity of the soil

Coffee grounds can be added to the soil when you want to increase its acidity slightly. Used coffee grounds have a pH of 6.8, which is ideal for acid-loving plants like tomatoes. However, be careful not to overload your tomato plants with a lot of coffee grounds. Tomatoes thrive well in a slightly acidic soil, not an over-acidic one. 

If you are in doubt about the acidity of coffee grounds, you can simply throw them on your compost pile to break down during the process of decomposition and use them later. Alternatively, you can place them in a microwave to dry before using them in your garden. 

5. Improves germination rate

Composted coffee grounds improve the germination rate of tomato seeds when mixed with the soil. It improves drainage, aeration, and water retention of the soil. These conditions are ideal for the proper development of young tomato roots.

Coffee grounds are also rich in nitrogen, potassium, magnesium, phosphorus, and other nutrients that ensure the seedling remains healthy. To achieve the best results, you simply mix the coffee grounds with garden soil in equal amounts. Place the seeds in the mixture and allow them to germinate.

6. Reduces the growth of weeds

Using coffee grounds as a mulch around your plants can help to prevent or reduce the growth of weeds. It also helps to preserve soil moisture content by reducing evaporation. Weeds are detrimental to your plants. They compete for nutrients, water, sunlight, and space with your plants. 

7. Can be used as a pest repellent 

Tomato plants are commonly attacked by small pests that destroy the roots, leaves, stems, or fruits. This can affect the quality and quantity of your harvest when not managed. However, you are not supposed to use a method that can harm or kill the plant when controlling the pests. This is now where the coffee grounds come in. 

Coffee grounds are a good pest repellent due to their smell and taste. Sprinkling the coffee grounds around your plants will keep away small pests like snails and slugs. The pomace is not toxic, but the smell deters the pests from accessing the plant. 

8. Regulates the soil temperature

Tomato plants require soil that is warm, and this is where the coffee grounds come in handy. When added to the soil, it ensures the temperature is well-regulated by improving drainage, aeration, and water retention. 

9. Reduces the growth of fungi

Late blight is a fungal infection that is characterized by lesions and yellowing of leaves in tomato plants. This infection is normally managed by the use of fungicides. Coffee grounds can also be used to control the fungi that cause late blight.

How to Use Coffee Grounds on Your Tomato Plants

Coffee grounds can be used to fertilize tomato plants in 3 different ways. Applying it directly at the base of the plants, composting the coffee grounds, or mixing it with mulching materials.

Applying coffee grounds directly around the plants

Although it is recommended to compost your coffee grounds, there is nothing wrong when you use it directly on your plants. It helps to add organic matter into the soil and hence improves drainage, aeration, and soil water retention. Scooping a handful and applying 1 to 2 should be sufficient for each tomato plant. 

However, it is important to leave some space around the plant. Don’t allow the coffee grounds to touch the tomato stem or leaves. It may introduce molds to your plants. Also, its high nutrient contents can chemically burn the plant.

Composting coffee grounds before use

You can mix coffee grounds with other materials like wood ash, shredded leaves, and lime to create the best compost fertilizer for tomatoes. This method also helps to lessen the acidity of the coffee grounds while increasing nitrogen levels. Using raw coffee grounds can make the soil too acidic for plants to thrive. 

Mixing with mulch

Coffee grounds can also be mixed with mulch and applied to the plants. Applying large volumes of coffee grounds on top of the soil can become compacted and prevent water from infiltrating into the soil. Mulch helps in breaking down the coffee grounds that may have become compact when applied alone directly. 

However, it is important to choose good mulching materials like dried leaves, pine needles, and bark. Poor choice of mulching materials can introduce weeds and pests into your garden.

How Often Do I Use Coffee Grounds on My Tomato Plants

When planting your tomatoes in pots, mix soil with coffee grounds in equal quantities and plant your seedling. Fertilize your plants when planting and once every 2 weeks. If you are intending to use a composited coffee grounds, be sure to prepare them early before the onset of planting season.

Coffee grounds are rich in nitrogen, which is required by the plant, especially during the growth stage. However, the plant requires other nutrients like phosphorus and potassium, especially when flowering, in order to produce high yields.

If the results you are seeing on your plants are below your expectations, you can simply add more coffee grounds to your plants and adjust over time. Remember that other conditions, like soil fertility, size of your plant, and climate, among other factors, can also determine the amount of fertilizer your plant may need. 

However, with organic fertilizer, you don’t need to be worried about whether you are using too much or too little fertilizer since you are not likely to see the negative effects.

It is recommended to use composited grounds. It contains lessened acidity. Raw coffee grounds can make the soil too acidic for the plants to thrive. However, you can use a Ph meter to determine the acidity of the soil.

Final Thoughts

Using coffee grounds to grow tomatoes is the best idea. It contains various nutrients that are important in the healthy development of plant roots, stems, leaves, flowers, and other tissues. Apart from that, it also enriches the soil with organic matter that improves soil aeration and drainage.