With its intricately patterned foliage, which resembles an artwork that brings grace and charm to your indoor space, the Calathea plant genus can be grown indoors year-round.
Though most houseplants aren’t heavy feeders, including Calathea plants, you must ensure to fertilize the plant at least once a month.
Fertilizing the Calathea plant allows it to grow luscious leaves. You can use a well-balanced organic fertilizer to enrich the potting soil.
Instead, you can also make your homemade fertilizer for Calathea. As this houseplant is known for its vibrant foliage, your fertilizer should be rich in nitrogen along with phosphorus and potassium.
Homemade organic fertilizer may have low levels of nitrogen. So, it is recommended to ensure the NPK value before applying the fertilizer.
You can use dry or liquid fertilizers to enrich the Calathea potting soil.
What Kind of Fertilizer Does Calathea Need?
Calathea is native to tropical rainforests, and it gets nutrients from the organic matter in dry leaves and stems. But indoor plants don’t have that option, so they depend on us (gardeners) to feed them essential nutrients.
Understanding the natural habitat of the plant helps determine its nutritional needs.
Most gardening experts recommend a balanced fertilizer to enrich the Calathea plant. Use 20-20-20 NPK value fertilizer or 10-10-10 to fertilize this houseplant.
But for bushy and vibrant Calathea plant leaves, you should opt for an NPK ratio of 3–1-2. Higher amounts of nitrogen encourage leaf growth, while phosphorus and potassium contribute to the growth of plant roots and stems.
Most homemade fertilizers are slow-fertilizers that release nutrients into the soil as they decompose.
So, you should use liquid fertilizers that are readily available for the plant to absorb.
9 Best Homemade Fertilizer for Calathea
Water and sunlight are among the essential needs of plant growth. However, it also needs macronutrients from the soil to form stems, develop roots, and produce foliage.
Like most plants, Calathea roots uptake nutrients from the soil along with water and deliver them to the plant.
Most indoor gardeners prefer store-bought organic fertilizers that are rich in NPK. If you’re interested in making or reusing your home’s available things as fertilizer, then this is for you.
Home-available ingredients aren’t rich in all three nutrients. As you already knew, this houseplant needs nitrogen-rich fertilizer. I recommend using different organic fertilizers to enrich the plant.
To solve this, most gardeners start composting at home. As the compost bin includes various organic ingredients, your plant can get balanced nutritional value.
However, below are different homemade fertilizers that can add essential nutrients to Calathea plants.
Composting not only supplies essential nutrients to your plants; it also reduces waste.
As a gardener, you should start composting your kitchen scraps. Adding brown and green material with some moisture helps prepare nutrient-rich fertilizer that is enough to fertilize your indoor plants, like Calathea.
You can also obtain liquid compost from the container and use it to enrich Calathea plants.
To increase the nitrogen content of your compost, add grass clippings, bone meal, and animal manure.
Don’t worry, old compost won’t smell. Add brown material to your compost to get rid of the bad odor.
How to use:
To give an initial boost to your plant, mix old compost with soil. During the growing season, you can spread compost around the Calathea plant and cover it with a layer of garden soil.
Regular watering will allow the Calathea roots to absorb nutrients released from the compost.
Being slow-releasing fertilizer, the Calathea plant gets nutrients throughout the season, so there is no danger of overfertilization.
Must Read: How to Use Mushroom Compost in Raised Beds?
2. Grass Clippings Fertilizer
Instead of throwing grass clippings, you can make nitrogen-rich liquid fertilizer from them.
The NPK ratio of grass clippings is 4:2:1. I.e., it has 4 percent nitrogen, 2 percent potassium, and 1 percent phosphorus.
- Fill 5 gallons of the bucket with grass clippings.
- Add water to the bucket.
- Before covering it with a plastic cover, add some Epsom salt and urine or active compost to start the anaerobic composting process.
- Keep the bucket under shade and stir regularly using a wooden stick.
- After 3 weeks, you will get nutrient-rich liquid fertilizer.
- Strain the liquid in a container and dilute it with water.
- Mix 1 part of this liquid fertilizer with 4 parts of water and use it to enrich your Calathea plant.
3. Cow Manure
The nutrient ability of animal manure needs no explanation. It includes 3% nitrogen, 2% phosphorus, and 1% potassium.
But you can’t directly use this manure to fertilize your plant.
Fresh cow manure contains bacteria that can affect plant growth.
Composting manure is the best way to use it as fertilizer. Add cow manure to the compost pile and allow nature to do the decomposition process for you.
Another way is vermicomposting.
Add helpful earthworms to fresh manure and let these worms eat the manure and secrete nutrient-rich fertilizer.
How to use:
Add decomposed manure to potting soil or apply it around the plant and cover it with a thin layer of garden soil.
Also Read: Is Cow Manure Good for Roses?
4. Coffee Grounds
It is not recommended to directly use coffee grounds to plant soil.
You must decompose it and then use the compost to enrich your Calathea plants.
Coffee grounds have 2% nitrogen, 0.3% phosphorus, and 0.3% potassium. Decomposed coffee grounds can be a good source of nitrogen for Calathea plants.
Add coffee grounds to your compost pile, but don’t exceed more than 20% of the total compost volume.
You can also make liquid fertilizer using coffee grounds. Add used coffee grounds to water and soak them for 1-2 weeks. Strain and collect the liquid. Dilute it with water and use it to fertilize Calathea.
How to use:
You can add composted coffee grounds to the soil or mix coffee grounds as a soil amendment.
Check out this: How to use coffee grounds to fertilize succulents.
5. Worm Castings
Add kitchen scraps and manure to a bin and let earthworms decompose them.
Obtained fertilizer will be rich in macronutrients and also include trace minerals essential for overall plant growth.
Worm castings have an NPK ratio of 5-5-3 or 1-0-0.
How to use:
Add worm-casting fertilizer to the potting soil while planting Calathea. You can also apply this fertilizer around the plant during the growing season.
6. Bone Meal
Bone meal is one of the offbeat organic fertilizers that can’t be ignored.
It is the powder of animal bones. Bones are steamed and ground into powder to be used as fertilizer.
With its rich source of phosphorus, bone meal powder is extensively used to fertilize flowering plants like hibiscus. However, it also contains nitrogen and potassium, along with other nutrients that help your Calathea plant grow.
The NPK ratio of bone meal is 3-15-0.
- Dry the bones to remove moisture.
- Steam them so that they can be ground into powder.
- Apply this powder to enrich your indoor plant.
How to use:
Mix bone meal powder into the potting soil, or you can also spread it on the top layer of the soil.
You can also make liquid fertilizer from bones. However, I prefer bone meal powder to fertilize Calathea.
7. Fish Emulsion
It is a liquid fertilizer made from the remains of fish. Unlike compost, fish emulsion quickly releases nutrients into the soil.
The NPK ratio of fish emulsion is 4:1:1. With its nitrogen content, it can help Calathea plants produce large and vibrant-colored foliage.
You can get fish emulsion from a local store, but if you prefer to make it at home, here is the process.
- Add fish parts, sawdust, and a cup of molasses to a bucket. Pour water into the bucket so that all ingredients are covered.
- Cover it with a lid with holes.
- Regularly mix all ingredients for 2 weeks.
- Strain the obtained fish emulsion liquid in a container.
How to use:
Dilute the fish emulsion liquid with water and use it to fertilize the Calathea plant.
8. Kelp Meal
organic fertilizer, which is obtained from dried and grounded seaweed. The NPK ratio of kelp meal is 1-0-4. Unlike most organic fertilizers, kelp meal releases nutrients quickly.
Get seaweed from the store and dry it, then grind it into powder to be used as fertilizer.
You can also make seaweed liquid fertilizer at home.
9. Aquarium Water
If you have a fish tank, the water you change contains valuable nutrients like nitrogen and trace minerals.
Use this water as a liquid fertilizer.
How Do I Apply Fertilizer to Calathea Plants?
Organic fertilizers release nutrients slowly, so your plant gets a regular supply of nutrients.
While planting Calathea, add old compost to the soil. This will ensure the plant gets an initial supply of nutrients to produce stems and leaves.
During the growing season, you can use bone meal or grass clippings as liquid fertilizer to encourage plant growth.
How Often to Fertilize Calathea Plants?
Spring and summer are the growing seasons for Calathea plants. If you’re using liquid fertilizer, dilute it with water before applying it to the plant.
Apart from this, you can add organic fertilizer once or twice a month.
Depending on the amount of sun exposure, you should regulate fertilizing.
In hot regions, fertilize once every 2 weeks. In colder regions, you can decrease it to once every 4 weeks.
In winter, you shouldn’t fertilize Calathea or any indoor plant. These plants go into dormancy due to low levels of sunlight.
Adding excess nutrients can result in discoloration of leaves, stunted plant growth, and a white layer of salts on the surface of the soil.
To revive, you should water regularly and stop fertilizing for 2–3 weeks.
Should you rely on these homemade organic fertilizers to enrich Calathea? No, along with these fertilizers, you should apply well-balanced organic liquid fertilizer to Calathea plants.
However, you can try homemade grass-clipping liquid fertilizer and see if the nutritional requirements of your plant are fulfilled.
Many more home-available ingredients can be used to fertilize indoor plants. But make sure to see the NPK ratio before applying it to the Calathea plant.
Khaja Moinuddin, a computer science graduate, finds joy in gardening and homesteading. Join him on this blog as he shares his experiences in homesteading, gardening, and composting