Coffee is a popular beverage, and coffee grounds are equally popular in the houseplant community. People use coffee grounds on their houseplants but often don’t know the effective ways to fertilize indoor plants with coffee grounds.
The best way to use coffee grounds on indoor plants is to add them to the compost or make a liquid fertilizer. Never toss coffee grounds into the soil as that can make the soil soggy, invite pests and diseases and hamper your plant’s growth. Also, avoid using it as a replacement for fertilizer.
Before you use coffee grounds to fertilize your indoor plants, I suggest you go through this article, so you don’t make any mistakes.
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Which plants do not like coffee grounds?
Although you can use coffee grounds on most indoor plants, some don’t enjoy coffee grounds:
- Sago palm
- Century plant
Avoid using coffee grounds if you have these plants.
What indoor plants benefit from coffee grounds?
Now let’s look at all the plants that love and will benefit from coffee grounds.
- Jade plant
- Snake plant
- Spider plant
- Christmas cactus
- African violet
These plants will benefit from the coffee grounds, provided you use them correctly.
Also read: Is Coffee Grounds Good For Indoor Plants?
Can I put coffee grounds in my indoor plants?
Coffee grounds can be very beneficial for your houseplants because coffee grounds are a rich source of Nitrogen which helps the plants grow.
Here are the 4 reasons why coffee grounds are great for indoor plants.
1. Coffee grounds are readily available
Coffee is a popular beverage in households, so you can easily get coffee grounds.
If you don’t drink coffee, you can get coffee grounds from your neighbors.
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2. Coffee grounds are a great source of Nitrogen
Coffee grounds are rich in Nitrogen, which is great for boosting growth in plants.
They also contain phosphorus which is an important macronutrient that the plants need.
Coffee grounds also contain micronutrients like calcium, magnesium, iron, etc., which can help indoor plants.
3. Coffee grounds are affordable
You can give your plants a boost of Nitrogen and other important nutrients without spending any money.
Since you already might use coffee grounds, you can get them without putting them in the kitchen waste and use them on the houseplants.
4. Using coffee grounds is eco-friendly
If you don’t use coffee grounds for your indoor plants, they will just go in the garbage dump.
So, when you use coffee grounds for fertilizing your houseplants, they get recycled and don’t contribute to more waste and pollution.
Hazards of using coffee grounds
If you don’t use coffee grounds correctly, they can harm your plant.
1. Coffee grounds can stunt the growth of young plants
You should not use coffee grounds on seedlings and young plants.
Mature plants can benefit from coffee grounds but will stunt young plants’ growth.
2. Coffee grounds can retain excess moisture
Coffee grounds have tiny particles that can retain excess moisture if you don’t use them the right way.
If you toss them on the soil, they will form a layer and retain excess moisture, making the soil soggy and overwatered.
3. Coffee grounds can invite pests
If coffee grounds retain excess moisture, they will invite pests.
Pests like mealybugs, aphids, scales, etc., love a moist environment and will infest plants that live in soggy soil.
4. Coffee grounds can lead to fungal infections
The wrong usage of coffee grounds leads to an environment that encourages fungal growth.
Fungal growth can lead to root rot and other deadly diseases that can kill your plant.
All the above hazards occur when you use coffee grounds the wrong way.
Your plant will reap the benefits if you compost or make liquid fertilizer from the coffee grounds.
How do you fertilize indoor plants with coffee grounds?
Let’s understand the 5 effective ways to use coffee grounds on indoor plants.
1. Make compost with coffee grounds
Instead of throwing the coffee grounds away, add them to the compost pile.
Compost is a great source of organic matter that helps the plants get all the nutrients that soil can’t provide.
Adding coffee grounds to the compost will add a boost of Nitrogen to the plants.
And the other organic matter will suffice for the other nutrients.
While creating the compost, you should create a balance of the greens and browns.
And never add more than 20% coffee grounds to the compost as that can harm the plant.
The ratio of “browns” to “greens” should be 3:1.
- The greens are elements that are high in Nitrogen, such as coffee grounds.
- The browns are matters that are high in Carbon, like dried leaves.
You can mix the compost with the soil or mix it with only the topsoil.
2. Make a liquid fertilizer with the coffee grounds
This is my favorite way of using coffee grounds on houseplants.
There are many ways to create a liquid fertilizer with coffee grounds.
Let’s look at the 3 common ways:
- Take a bowl or container and add some water to it.
- Now put the coffee grounds into the water.
- Leave it aside for 1-2 weeks.
- Don’t forget to stir it every few days.
Once the coffee grounds break into the water, they will release nutrients.
You can then use this water to fertilize your indoor plants.
- Take a sock and put the coffee grounds into it.
- Now place the sock in a bucket of water.
- Leave it aside for some days.
- The coffee grounds will break and release the nutrients into the water.
- Once you notice that the color of the water has changed, you can use it to fertilize the plant.
- Add some water into a container.
- Now, put the container on the gas and turn it on.
- Allow the water to simmer.
- Turn the gas off.
- Let the water cool down.
- Once the water cools, add the coffee grounds to it.
- Leave the mixture aside for 7-14 days.
- Keep stirring it occasionally.
- Once you notice the coffee grounds breaking into the water, strain it and use it to fertilize your plant.
3. Mulch with coffee grounds
Mulching is usually done in the gardens, but you can do it for your houseplants too.
- First, create a mixture of coffee grounds and organic matter like leaves and barks.
- Make sure the coffee grounds are spread evenly.
- Now spread a layer of this mixture over the soil of your houseplant.
Keep in mind that the layer of the mulch should be light, or it will form a barrier and retain excess water.
4. Add coffee grounds to the potting mix when repotting
If you want to use coffee grounds as a slow-release fertilizer, you can mix it with the soil while repotting your plant.
Since coffee grounds contain Nitrogen, phosphorus, and other nutrients that the plants need, it can be a great slow-release fertilizer than can work for up to 6 months.
Don’t go overboard with adding coffee grounds to the soil, as that can harm your plant.
When using coffee grounds while repotting your houseplant, add one-fourth cup of coffee grounds for 4-6 cups of soil.
Mix these very well.
You can add sand to the soil to ensure the drainage system works well.
5. Mix coffee grounds with the top layer of the soil
If you are not repotting your plant or don’t want to make compost of liquid fertilizer, try mixing coffee grounds with the topsoil.
Since coffee grounds can form a barrier and retain excess moisture, you need to be very careful not to use excess coffee grounds.
Add 1 or 2 teaspoons of coffee grounds to the topsoil and mix them well.
However, don’t use this for cacti and succulents.
Can I use leftover coffee to water plants?
You can water your plants with leftover coffee, but you must be extra careful.
Keep the following in mind to avoid any mistakes:
- Always dilute the coffee before using it to water your plants.
- Never use coffee that is too hot or cold. Use it only when it is at room temperature.
- Don’t use coffee too often on your plants.
- Keep your cats and dogs away from the plants you fertilize with coffee grounds.
- Don’t use this on seedlings on young plants.
- Use leftover coffee only if it doesn’t have any flavor, sugar, cream, milk, etc. If you drink black coffee, you can dilute it and water your plant with it.
You will notice fast and healthy growth if you can use coffee grounds the right way on your indoor plants.
Be careful if you use unwashed coffee grounds on your houseplants, as these can make the soil acidic. Many people confuse this with used coffee grounds. But, you should not worry about the soil pH while using used coffee grounds as these have neutral pH levels.
The most effective way of using coffee grounds on indoor plants is to add them to the compost or create a liquid fertilizer. I have also mentioned three other effective methods in the article that you can choose from.
Source: Coffee grounds benefits, Field Evaluation of Coffee Grounds Application for Crop Growth, Effect of fresh and composted spent coffee grounds.