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Did you know that even houseplants need fertilizing every once in a while? It’s true, and calatheas are no exception. 

Even though they are not heavy feeders, you should still fertilize a calathea once a month during its active growing season. This helps to promote healthy growth, which all plants can benefit from. 

Keep reading to learn more about calathea fertilizer and how to properly apply it to this tropical houseplant.

a woman watering a calathea with fertilizer

What fertilizer is best for Calathea?

Jack’s Classic All Purpose 20-20-20 Fertilizer with micronutrients is a good choice when you want to fertilize a calathea. This fertilizer is water soluble and can be used for indoors and outdoor plants, vegetables, trees, and even turf.

(You can check the latest price of Jack’s Classic 20-20-20 Fertilizer here.)

It works well for calatheas, since they need a fertilizer with a balanced NPK ratio, and the added micro-nutrients are a plus and can help promote healthy and strong root and foliage growth.

If you’re looking for the best organic fertilizer for calathea, consider Neptune’s Harvest Fish & Seaweed Fertilizer. This all-purpose fertilizer works well on both indoor and outdoor plants, and is made from various fresh caught fish from the North Atlantic. It’s a good choice if you’re looking for a calathea fertilizer that is organic and natural.

As you can probably guess though, before you even begin to fertilize a calathea, you will need to determine which is the best fertilizer for calathea plants. Unfortunately, you can’t use just any old fertilizer for the calathea and using the wrong kind can cause more problems than good. 

Thankfully, the calathea usually does well when fed an all-purpose, liquid fertilizer, like the ones I recommend above.

Do Calatheas like Miracle Gro?

There are a few different options for Miracle Gro fertilizer that work well for Calatheas. The best is Miracle Gro Indoor Plant Food, which is a balanced liquid fertilizer with a NPK ratio of 1-1-1. It is easy to use and can be applied directly to the soil or diluted in water.

Check the up to date price of Miracle-Gro Indoor Plant Food here.

Miracle Gro has long been a leader in the plant food industry, so it’s not uncommon that people would wonder if this fertilizer is a good choice for Calatheas. 

Fortunately, not only is Miracle Gro readily available, but it also makes a wonderful fertilizer option for tropical houseplants like Calatheas.

Miracle-Gro indoor spikes (check the latest price of these here), which are small spikes or rod-like sticks that you insert into the soil of your houseplants, are another option if you want to fertilize a Calathea. According to Miracle-Gro, the spikes can feed the plant for up to 2 months.

What calathea fertilizer ratio should I use?

Calatheas needs a balanced fertilizer, so look for one with an NPK ratio of 10,10,10. Additionally, you should only use liquid fertilizer and not granules or pellets that release feed into the soil over a period of time. 

These types of “slow release” fertilizers can increase the chance of accidently overfertilizing the calathea.

How to fertilize Calathea

1. Choose your fertilizer

The first step in fertilizing calatheas is to choose the fertilizer you are using. There are several different options for this houseplant, including organic and commercially available options. 

Once you have your fertilizer selected, you can begin feeding the calathea.

2. Water the calathea thoroughly

A day or two before you plan on feeding the calathea, make sure that you thoroughly water the plant. 

If you fertilize a calathea when its soil is dry, you run the risk of burning its roots, which can have a negative impact on the overall health of the plant.

Related: How Often to Water Calathea Plants (So They Thrive)

3. Dilute the fertilizer

Some of the fertilizers you can use for calatheas will need to be diluted before you can apply them. This means mixing the fertilizer with water beforehand. 

For commercially available fertilizers, you should dilute them at about ½ of its strength. It’s best, however, to follow the instructions on the label of the fertilizer you are using.

Not all calathea fertilizers need to be diluted, however. Compost and worm castings, for example, can be mixed into the calatheas soil, or simply sprinkled on the top of the soil, without first being diluted.

4. Apply the fertilizer

Once you have the fertilized diluted, if necessary, apply the feed to the calathea. Depending on the type of calathea fertilizer you choose, this may mean simply watering the plant or performing a soil drench. 

If you are using compost or worm casting, however, sprinkle the fertilizer over the top of the calathea’s soil.

The best way to determine how to apply the fertilizer correctly is to refer to the application instructions, which are typically found on the back of the fertilizer bottle or packaging.

someone spraying calathea with fertilizer

5. Reapply once a month

Wait for about 4 weeks before reapplying the fertilizer. This should only be done during the spring and summer, and all feeding will need to be stopped during the fall and winter months. 

If you fertilize a calathea during the fall and winter, you run the risk of disrupting the plant’s natural growth cycle.

6. Watch for signs of overfertilization

Overfertilization is a real problem for houseplants, and it occurs when the wrong type of fertilizer or too much fertilizer is used. This can lead to calathea yellowing leaves, stunted growth, leaf drop, and a white or gray buildup of minerals on the soil’s surface.

If you notice any of these symptoms, immediately stop all feeding and then flush the calathea’s soil. This will require allowing lukewarm running water to flush the plant’s soil for several minutes.

How often should I feed my Calathea?

Calatheas are not heavy feeders and you will only need to fertilize a calathea once a month during the spring and summer. All feeding should be stopped during the winter, which is when the calathea’s growth rate slows or stops. If you feed during this time, it will disrupt the plant’s natural growth cycle.

Remember, each situation is different and you may have to feed the calathea less than once a month. 

Additionally, you should always refer to the application instructions listed on the fertilizer bottle. Each brand and type of calathea fertilizer has its own specific application directions that should be followed for the best results.

calathea with fertilizer on a pot

Should I water the Calathea before or after fertilizing it?

Calatheas should be watered thoroughly before applying the fertilizer. This helps to prevent root burning, which can occur if you apply calathea fertilizer to a plant with dry soil. Additionally, the fertilizer should be diluted with water before applying so as not to burn the plant’s foliage.

Another thing to consider is the type of water you use. Calatheas can be sensitive to tap water, due to the additives that some cities put into tap water. Chlorine, fluoride, salts, and extra minerals are just a few of these things added to tap water.

These extras often found in tap water can actually harm the calathea. That is why most gardeners use distilled, filtered, or even rain water to hydrate the calathea.

What is the best homemade fertilizer for Calathea plants?

The best homemade fertilizer for calathea plants is rather simple, requiring only water and either kelp meal or fish emulsion. To use, you must first dilute ½ teaspoon of kelp meal or fish emulsion in 1 quart of lukewarm distilled water and then simply water the calathea with the mixture.

This is a great alternative to chemical fertilizers and can help feed the calathea while also reducing the chance of burning the plant. That doesn’t mean, however, that you cannot over fertilizer the plant with this homemade mixture. Thankfully, if you stick to applying the homemade fertilizer once a month, you shouldn’t have any problems.

calathea with fertilizer on a wooden pot

Is coffee good for Calathea?

While coffee grounds and the calathea’s ideal soil may have the same pH level, you should still avoid adding coffee to the calathea. Coffee contains caffeine, which can be transferred to the plant causing all kinds of issues. 

Additionally, any nutrients you may find in coffee cannot be properly absorbed by plants until it is composted.

What this means is that, once the coffee has been composted, it can be added to the calathea’s soil. If you don’t compost first, you are potentially robbing the calathea of nitrogen and can even create an environment that is perfect for fungus gnats, mold, fungus, and bacteria.

Is fish fertilizer good for Calatheas?

Fish emulsions are a favorite organic fertilizer among many gardeners, including those who grow calatheas. For those who are unsure as to what fish emulsion is, it is fertilizer made from leftover fish scraps. This organic calathea fertilizer helps to encourage healthy growth in a more natural way.

Keep in mind that, even though fish fertilizer is considered one of the best organic fertilizer for calathea, that doesn’t mean that you cannot over fertilize the plant with it. In fact, you can over fertilize the calathea with any fertilizer, even if it is all-natural or organic.

calathea with fertilizer and other plants

Can I use worm castings on Calatheas?

Worm castings are a good choice for calatheas since this plant isn’t a heavy feeder, and worm castings provide a more light and gentle feeding option. To use castings, simply incorporate it into the top inch of soil in the calathea’s pot.

Worm castings are readily available from local garden centers, as well as various online merchants. You may even have a local worm farm nearby that can sell you the castings in bulk.

Signs your Calathea needs fertilizer

There are several signs that could indicate that you should fertilize a calathea, including slowed growth, leaf discoloration, and leaf drop. 

Unfortunately, many of these symptoms could also be a sign of other common problems, such as improper watering. That is why you will need to do your due diligence to figure out the root cause.

1. Stunted growth

The most common sign that you should fertilize a calathea is that it will experience stunted growth. Without the right nutrients, the plant just cannot grow properly. This will result in the plant just not growing properly.

Unfortunately, stunted growth is a common sign associated with a wide array of problems, not just lack of nutrients.

2. Yellow leaves

Another common symptom of nutrient deficiency in calathea is yellowing leaves. When a plant doesn’t receive the right amount of nutrients, its foliage will start to discolor, in most cases yellowing of the leaves.

calathea with fertilizer on a gray pot in the stairs

3. Small leaves

New leaves that emerge much smaller than normal is another sign that the calathea needs fertilizer. 

The sad truth is that this plant needs nutrients to produce large, stunning foliage. And if you don’t provide the needed fertilizer, all new leaves will be smaller than before.

4. Pale colored leaves

Leaves that are not yet yellow and are simply pale in color could be a sign that the calathea needs fertilizing. 

Sometimes, this pale color is light and hard to notice, but can start to get more noticeable the longer the calathea goes without proper nutrients.

5. Deformed foliage

Another potential sign that the calathea is lacking nutrients is that its foliage starts to twist, curl, and become deformed. 

In most cases, the deformed foliage begins at the lower leaves, and will slowly take over the entire plant if you don’t provide the proper calathea fertilizer ratio.

a healthy calathea with fertilizer

Signs your Calathea is over fertilized

While not fertilizing your calathea can cause problems, so can overfertilizing it. Too much calathea fertilizer will leave your plant with discolored leaves that may begin to fall off the plant. 

Familiarizing yourself with the most common symptoms of overfertilization will help you quickly spot a problem.

1. A crusty substance is forming on the soil surface

This crusty substance is typically white or gray in color, and there are excess salts building on the surface of the soil. This occurs when too much fertilizer has been added and the plant can no longer absorb any additional nutrients.

2. The calathea has yellow leaves

While yellowing of the leaves is a common symptom of many problems, including overwatering, it could also signal that the calathea has been overfertilized. 

That is why it is best to look for other potential problems, such as excess salt forming on the soil surface, to confirm the yellow leaves are caused by improperly fertilizing the calathea.

calathea with fertilizer on a pot with design

3. Bottom leaves are wilting and falling off

The bottom leaves are usually the first part of the plant that becomes affected when you apply too much calathea fertilizer. They will begin to wilt and even fall off the plant. 

Simply pruning the wilted leaves off the plant may make the calathea look better, but this is a temporary fix that won’t correct the underlying problem.

4. Leaf tips are browning

Another potential symptom of overfertilizing a calathea is that the plant’s leaves will begin to turn brown.

5. The edges of the foliage are starting to turn brown

Along with the tips of the leaves, you may also start to notice that the entire edge of the leaves are turning brown. This typically occurs because too much fertilizer prevents the calathea from properly absorbing watering.

Related: 12 Causes of Brown Spots on Calathea (+ How to Fix It)

6. Roots are brown, black and limp

Healthy roots are white or cream in color and are rather stiff. If you see the roots are black or brown, and limp, then it could be a sign that the plant is being over fertilized. 

This symptom is a bit harder to see since it happens underground.

7. The calathea has lost its leaves

Too much fertilizer can also cause the calathea to lose all of its leaves. Keep in mind, however, that this is also a sign of underwatering. To confirm whether or not the defoliation is caused by lack of water, check the calathea’s soil.

If it is extremely dry, then you may just have to increase the amount of water you give the plant. If the soil is still moist, the problem could be due to applying too much calathea fertilizer.

What can I do if I have overfertilized the calathea?

If you have overfertilized the calathea and it is starting to show signs of too many nutrients and minerals, you may be able to save the plant by either flushing the soil or repotting the calathea in fresh soil.

To flush the soil, hold the calathea under lukewarm running water and let the water flush out any excess nutrients trapped in the soil. 

calathea with fertilizer on a brown pot near the window
Source: Lulu Lulík (CC BY-SA 4.0)

Repotting the calathea is a bit more intense and does require removing the entire plant from its pot and getting rid of all the soil.

Once all the soil has been removed, repot the calathea in a clean pot with fresh oil. Water the plant thoroughly and avoid feeding the plant for a while until it starts to get healthy again.

Will fertilizing a Calathea promote leaf growth?

Calatheas are grown for their stunning foliage, so it is only natural to wonder if calathea fertilizer will help promote leaf growth. Calatheas don’t like a lot of feeding, but giving them some fertilizer during their active growing period goes a long way to encouraging strong and healthy leaf growth.

Feeding during the spring and summer will also promote strong growth and an overall healthy plant. Just remember that you can overfeed plants, and trying to bulk up on the calathea’s foliage by increasing the fertilizer will also burn up the plant.

Keep in mind, however, that merely applying calathea fertilizer is no substitute for proper care. 

An unhealthy and neglected calathea will not snap back with fertilizer. Instead, give the calathea its ideal growing conditions and use fertilizer to help support the good gardening practices you have implemented for your houseplants.