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Are Coffee Grounds Good for Houseplants? (The Secret Fertilizer)

Fertilizing is key for plants, especially when their roots are confined to small spaces, to get all the essential nutrients they need for healthy, lush growth. But you don’t have to break the bank on expensive mineral solutions from stores. Used coffee grounds can be an excellent alternative.

Coffee grounds are rich in minerals that plants love. They’re an effective way to nourish your indoor plants, releasing their benefits slowly into the soil and plants.

By regularly using coffee grounds as a fertilizer, you can actually skip the need for chemical fertilizers altogether. So, not only are you saving money, but you’re also opting for an organic approach to plant care.

Benefits of Coffee Grounds for Indoor Plants

Coffee grounds offer several benefits for indoor plants, mainly because they are packed with essential minerals. They can help to reduce soil acidity, making the soil lighter and more permeable.

Nutrient Content

Coffee grounds contain about 1.5% nitrogen, similar to decomposed plant materials.

They’re a fantastic source of phosphorus and nitrogen compounds, and also contain calcium and magnesium, each of which positively impacts plant health.

Key Minerals and Their Benefits

  • Phosphorus: Speeds up the formation of buds, enhances flowering and root development, and aids in fruit ripening.
  • Nitrogen: Fuels the growth and overall development of the plant.
  • Calcium: Supports the healthy development of roots, stems, and leaves.
  • Potassium: Provides frost resistance to plants and flowers, helping them survive the winter and ward off various pests.

In addition to these core elements, used coffee grounds also contain traces of copper, iron, carbohydrates, and other micro-elements.

Coffee grounds offer some awesome benefits for your plants:

  • They boost soil acidity, which is great for plants that thrive in acidic conditions.
  • They improve soil aeration. Adding coffee grounds makes it easier for oxygen to reach the roots and loosens up the soil around your plants.
  • They repel pests. The smell of coffee can drive away certain bugs, like fruit flies.

How to Prepare Coffee Grounds for Fertilizing Indoor Plants

Coffee grounds can work wonders as a fertilizer or soil additive for your indoor plants, but it’s essential to prepare them correctly.

Preparation Steps

  1. Use Only Used Coffee: Freshly ground coffee is not suitable. Stick to using the spent grounds.
  2. Collect Promptly: Gather the coffee grounds right after you’ve had your cup, instead of putting it off, to prevent mold.
  3. Drying Options: You can dry the coffee grounds on a sheet of paper or in the oven until they reach a crumbly texture.
  4. Direct Application: If you plan to use the grounds as fertilizer, there’s no need to dry them. Simply mix the wet grounds with water in a watering can and water the plants that need a nutrient boost.
  5. Storage: Store dried coffee grounds in an airtight container in a dry place.

Interesting Fact! Restaurants and cafes often place spent coffee grounds, extracted from coffee machines. You can take multiple packages at once if you’re a patron.

Which Plants Can Benefit from Coffee Grounds

Some houseplants especially love coffee grounds. These include:

  • Roses
  • Begonias
  • Azaleas
  • Ferns
  • Violets
  • Poinsettias

Other indoor plants will also appreciate this kind of fertilizer, but you’ll want to introduce it gradually and in small amounts.

To know which plants will thrive with coffee grounds, consider their preference for soil acidity levels.

Don’t hesitate to experiment with coffee grounds. They are rich in nutrients and can even change the color of your blooms, often leading to unexpected results. But use them judiciously.

For outdoor flower beds, introduce coffee grounds from March to April, focusing on new shoots. Continue to fertilize every 2-3 weeks until warmer weather sets in.

Coffee grounds can be a multi-purpose tool in your rose garden. They can help protect your rose bushes from snails, gnats, and ants. Simply prepare a solution and spray it on the plants.

Flying insects like Japanese beetles can significantly reduce a flower’s aesthetic value. After a coffee spray treatment, they’ll steer clear due to their aversion to the coffee smell.

Adding coffee grounds to the soil makes it easier to aerate and nourish the roots and stems of your roses, accelerating the growth of new shoots.

Be aware that coffee additives could change the color of your flowers. For example, pink roses might turn violet after regular coffee treatments.

With coffee fertilizers variegated plants will grow much faster than their unfertilized counterparts, and the contrasting leaf colors will be more vibrant.

For peonies, tulips, and lilies, spent coffee can be useful in fighting off slugs that feast on their bulbs.

How to Use Coffee Grounds for Houseplants

Coffee grounds are versatile and can be used in various aspects of gardening. Here are some effective ways to utilize them for your indoor plants:

  • Place coffee grounds at the bottom of your pots to act as an additional drainage layer.
  • Prepare a solution by mixing 1 tsp of coffee grounds in 1 quart (1 liter) of water. Use this mixture for regular feeding.
  • For a more potent feed, combine equal parts coffee grounds, half-parts dried leaves, and straw. Mix them together and let them compost in a pot. To speed up the process, cover the mix with a thin layer of soil and poke a few holes in it. After a month, it’s ready to be added to your pots and flower beds.
  • Sprinkle dry coffee grounds on top of the soil, around the base of your plants. Store coffee grounds in glass, metal, or plastic containers to keep moisture out.
  • Add coffee grounds to your soil mix, using no more than 10% of the total soil volume.
  • Water your sick plants with coffee grounds to neutralize pests or deter them if they don’t like the smell.

Common Mistakes to Avoid with Coffee Grounds

Many people don’t realize that coffee grounds can be a fantastic fertilizer for houseplants. While it’s cost-effective and very efficient, you should stick to some guidelines and dosages for the best results.

Don’t Use If:

  • Milk was added to the coffee, as it could lead to the growth of harmful pathogens.
  • The coffee contained fruit additives or sugar.
  • It’s simply unused ground coffee.


  • Always dry wet coffee grounds.
  • If you don’t give adequate breaks between feedings, you risk attracting gnats.
  • Never use instant coffee as fertilizer; its high acidity can kill your plants.
  • Don’t use coffee grounds as a top layer without mixing it with sand or soil, as it may form an impermeable layer.
  • Avoid using coffee grounds on succulents and cacti.

Coffee grounds are a modern, eco-friendly way to fertilize your indoor plants. Used correctly, they can replace expensive chemical fertilizers, protect against pests, and help you grow beautiful houseplants.

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