Are Coffee Grounds Good for Tomato Plants?

Gardeners and even people who take care of indoor plants have raved about using spent coffee grounds on their plants as a fertilizer. It saves them the trouble of buying commercial fertilizer, and they get a freshly brewed cup of coffee every time they decide their plant needs more nutrition. But are coffee grounds good for plants like tomato plants?

Coffee grounds are good for tomato plants in small amounts. Mix a small amount of grounds with mulch or other fertilizers for best results. Coffee grounds act as a slow-release fertilizer that will benefit the tomato plant as the grounds decompose into the earth.

While coffee grounds are beneficial to your tomato garden, you can’t use them as your only fertilizer, or you could scorch the plants. There is a proper amount of grounds to be used at a time. This article will help you figure out how to get the best from your coffee grounds for your tomato garden.

An image of Coffee beans and ground coffee.

How Do You Use Coffee Grounds on Tomato Plants?

The best way to use coffee grounds on tomato plants is to make a coffee ground fertilizer by mixing up to 20% coffee grounds with 80+% compost or mulch for best results. Let it compost for a while first for best results, then use it on the tomato plants.

It would help if you mixed-used coffee grounds with your mulch but remember not to add too much of it. Just to be sure, I like to keep my ratios of the compost or other fertilizer to 80 percent and coffee grounds to no more than 20 percent of the mixture. 

Wait for it to compost properly, especially if you’re making homemade fertilizer out of the compost. Once it’s well-composted, add the fertilizer into the planting hole before transplanting your tomato seedlings.

By adding your homemade fertilizer with coffee grounds to the growing plants, you are providing them with slow-release nutrients as they grow.

How Often Should I Put Coffee Grounds on Tomato Plants?

Coffee grounds can be used before planting tomato seedlings, up to a couple of times during the summer, and during early fall. If coffee grounds are a new garden addition, put them in the compost pile before using them directly on the ground. A test used grounds on one plant before using it broadly.

During the summer months, you can add mulch mixed with coffee grounds throughout the summer. This will conserve moisture, prevent weeds from growing and add nutrients to the soil.

You can till coffee grounds into the soil without waiting for it to compost when falls set in and allow the grounds to decompose naturally. According to a study done by the University of Florida Extension, you can do this about twice a year or even more.

Can Coffee Grounds be Used in a Compost Tea on Tomatoes?

Used coffee grounds can be used to make a compost tea for use on tomatoes. Do not make a compost tea out of unused coffee or coffee grounds.

Add 2 cups of used coffee grounds to 5 gallons of water. Let it steep overnight, and by the morning, you have coffee ground compost tea. Then, you apply your tea directly to the soil with either the sprayer or even a watering can. You can also use the tea as a foliar feed by spraying it on the leaves and stems of your tomato plants.

Remember to always start small and test with a single plant or two. You can always expand your use of compost tea, but you can’t take it back once you’ve used it.

What Are the Other Benefits of Using Coffee Grounds?

Aside from working as a slow-release fertilizer, coffee grounds are still plenty useful for many things for gardening. Leftover coffee grounds can be used to feed worms in a worm farm or vermiculture. Take it easy with the amount of coffee grounds used with worms; too much acidity can be harmful to them.

They are also said to help keep pests like slugs from visiting your garden. Since coffee grounds are abrasive, you can make a barrier around slug-prone areas. While this isn’t 100% proven, there’s no harm in trying.

Pro tip: chickens are great for getting rid of slugs and snails. They keep my garden free of slugs and snails – and our garden used to have a ton of snails!

Can I Use Fresh Grounds Instead of Spent Grounds?

For some plants, fresh grounds would be a better option, but spent grounds are better for tomatoes. Acid-loving plants would love fresh grounds that haven’t been used yet, but tomatoes are not a fan of too much acidity.

Also, why waste a perfectly good cup of coffee? Instead, enjoy your daily morning coffee and get a chance to use the spent grounds to add nutrients to your tomato garden.

Personally, I prefer herbal teas – I don’t even drink coffee. But I can imagine many of my friends crying if I poured perfectly good coffee on a plant.

What is the Best Fertilizer for Tomatoes?

Tomatoes are a type of heavy feeder and require a lot of nutrients to be able to grow well throughout the different seasons. Fertilizer can either be chemical or organic; it doesn’t matter if it can provide the necessary nutrients.

First, have your soil tested. That way, you’ll know what nutrients your soil needs to grow tomatoes. Your local university agriculture extension will be the best place to test your soil.

If it’s balanced or has high nitrogen, use a fertilizer with slightly lower nitrogen and higher phosphorus. You can also provide phosphorus instead of harsh fertilizers. 

How Many Times Do I Need to Fertilize My Tomato Plants?

Fertilize soil before transplanting tomato seedlings, fertilize again when transplanting, and fertilize tomato plants again up to every two weeks. It’s better to fertilize around the plant rather than apply the fertilizer directly to the plant.

Tomatoes are some of the trickier vegetable crops you can choose to grow. However, all the time and care you’ve put into your garden is sure to be fruitful once it’s time to harvest. You should fertilize your soil before transferring the seedling to your garden. Once you notice fruit growing, you can start adding light fertilizer about once every week or once every two weeks. 

When you fertilize the plant initially, put some fertilizer at the bottom of the planting hole. After putting fertilizer, put another layer of unfertilized soil to protect your plant’s roots. While tomatoes need fertilizers, their roots tend to be sensitive and will burn if it touches the fertilizer directly. 

When fertilizing the tomatoes, once the fruits are growing, make sure to spread fertilizers around 6 inches away from the plant’s base. If you fertilize too close, you risk burning the tomato plant.

an image of a tomato plant growing

How Can I Tell if I Placed Too Much Fertilizers on My Tomato Plants?

Overdoing it with fertilizer is a common issue with tomatoes. Signs of overfertilizing include few growing tomatoes; tomatoes with poor color, texture, and flavor; and a plant growing out of control without many tomatoes could also mean that the fertilizer has more nitrogen than needed. 

You should check other signs to see if your plant has had too much fertilizer. For example, you can check if the plan has been dropping too many blossoms. Another sign is if the leaves tend to roll. There’s an easy remedy to all of this. All you need to do is adjust the amount and frequency of your fertilizer.

Once you’re successful with growing your own tomatoes, you’ll find it hard to go back to store-bought grocery ones. It’s always rewarding and cost-efficient to be able to grow your own produce at home. If you’re able to make use of your cup of coffee from this, then all the better.

Key Takeaways

Now that you know more about using coffee grounds on tomato plants, make sure you know more about using them on other garden plants. Here are some of our top articles on using coffee grounds in gardening.

Or you may want to read more of our articles about tomato plants.

They’re all great, so go ahead and give them a read next!

Cite this article as: “Are Coffee Grounds Good for Tomato Plants?” Backyard Homestead HQ, 22 April 2022, backyardhomesteadhq.com/are-coffee-grounds-good-for-tomato-plants/.

Resources

It’s important to learn from your own experience, but it’s also smart to learn from others. These are the sources used in this article and in our personal research to be more informed as homesteaders.

  • “Home Garden Remedies, Helpful or Harmful?” University of Florida, 24 July 2020, blogs.ifas.ufl.edu/highlandsco/2020/07/24/home-garden-remedies-helpful-or-harmful.
  • Moulton, Madison. “Are Coffee Grounds Good For Tomato Plants? Err, Probably Not!” Tomato Bible, 26 Apr. 2021, www.tomatobible.com/coffee-grounds-tomato-plants/.

By Kimberly Starr

I'm a ginger who loves being outside, homesteading, and spending time with my family. I believe humor is the best medicine, followed very closely by chocolate and tacos.