Everything You Need to Know About Fertilizing Calathea Plants Grown Indoors 

Calatheas (aka prayer plants) are admired for their patterned leaves and lush foliage. Unlike some other plants that share that common name, these houseplants need a specific fertilization routine to keep them healthy. For a bold and colorful Calathea that thrives all year round, make sure you’re adjusting how much you fertilize between winter and summer. You’ll need to choose the right fertilizer as well.


Fertilizing Calatheas – The Essentials

Calatheas are relatively low feeders that nonetheless need occasional fertilizer. Choose a nitrogen dominant product with an NPK ratio of 3-1-2. Liquid fertilizers are the easiest for these houseplants, but other products can work well if they’re not designed for slow release. Stop fertilizing in the winter.


Why Do Plants Need Nutrients from Fertilizer?

Why Do Plants Need Nutrients from Fertilizer?

Calatheas rely on water and sunlight for most of their needs, but macronutrients also play an essential role in plant health ensuring your plant is sufficiently healthy to keep bugs, pests, and diseases at bay

Secondary nutrients and even micronutrients also help certain plants grow strong and healthy, while other species may not need them at all. 

The three macronutrients for plants are nitrogen, potassium, and phosphorous. Required for creating amino acids and operating the plant’s metabolism, these nutrients and others are generally supplied by an appropriate soil base first. But for houseplants grown in containers, fertilizer is usually required.

Whether used for houseplants or agricultural fields, there are a few common types of fertilizer available to feed plants:

  • Dry pellet fertilizer, the most common form used on lawns and large crop fields.
  • Dry powders, usually derived from mineral ingredients but sometimes organic in nature.
  • Liquids, easy to measure and apply to houseplants, with dilution allowing to fertilization of smaller and younger plants.
  • Water-soluble powders, easy to store but just as easy to apply as liquid fertilizers.
  • Raw organic materials like sifted compost or aged manure, harder to apply on a small scale like houseplants due to the smell or issues with spills.
  • Other dry slow-release products, including simple spikes or discs designed to be buried near the roots.

Fertilizers are either derived from raw minerals mined from the earth or organic materials like manure and compost. Mineral fertilizers are more direct and easier to control the precise application. 

They’re also less messy for indoor applications like Calatheas grown as houseplants.


Signs Your Calathea Plant is Lacking Nutrients and Needs Feeding

Signs Your Calathea Plant is Lacking Nutrients and Needs Feeding

Yellowing and fading leaves indicate that a Calathea is no longer getting all the nutrients it needs from its soil. Since this plant isn’t a particularly heavy feeder, fresh potting soil with compost or fertilizer mixed in will likely keep it going for a year or two. 

However, after that point, the nutrients are generally depleted. A Calathea stuck in soil with no fertilizer may show signs like fading and loss of color first. Then the leaves will yellow, with slow growth to replace the foliage lost naturally over time. 

Mild wilting and drooping that doesn’t respond to watering or light changes may be caused by a lack of fertilizer as well. In these instances, consider pruning your Calathea plant to cut back past prime foliage.

When and How Often Should You Fertilize Calatheas?

When and How Often Should You Fertilize Calatheas?

Calatheas are not heavy feeders and don’t need a dose of fertilizer every time they’re watered. Also, it’s best to avoid fertilizing recently propagated calathea plants until they’ve had a chance to naturally develop.

Instead, focus on fertilizing the plant once per season in the spring, summer, and fall (the best time to consider repotting as well). Space these fertilizer doses out by about eight weeks or more to ensure the plant isn’t being overfed.

If you have a particularly large Calathea or the species is known for needing more feeding, try a diluted dose once a month during these seasons. It’s better to slightly under-fertilize than to overfeed the plant since you’ll be able to tell it needs more from fading colors.

If the Calathea is not actively putting out new leaves, don’t fertilize it unless you think that’s why. A lack of proper light or watering conditions can’t be overcome with more fertilizer. Only humidity and indirect light will allow the plant to take advantage of the nutrients. 

If you add too much fertilizer to the soil, emptying the container and replacing the potting mix will help the plant.

The Best Fertilizer for Calatheas

The Best Fertilizer for Calatheas

Calathea prefers more nitrogen than the other two macronutrients, and only needs a small dose of trace nutrients from the soil. 

An NPK (Nitrogen-Phosphorous-Potassium) fertilizer ratio of 3-1-2 is recommended, with urea or ammonia-based nitrogen preferred. This means that liquid or dry fertilizers based on minerals are preferred to those made with organic materials. 

The exception is composted manure or manure extracts that often contain plenty of urea-derived nitrogen. Fish emulsions and kelp liquids can also be good choices for these reasons. 

Compost and other homemade fertilizers tend to be too low in nitrogen for these houseplants. Coffee grounds are one convenient homemade fertilizer that is easy to apply to these plants. 

They’re primarily rich in nitrogen and only release a small dose of it while adding a nice smell as they dry. These plants can also handle the slightly acidic nature of the grounds.

How to Apply Fertilizer

Liquid fertilizers allow immediate access to the nutrients and even distribution through the soil. 

Dilute the fertilizer by half to see how the plant reacts first. Work up to a full-strength application of a 3-1-2 fertilizer only if the houseplant shows signs of needing it. 

For most Calathea, half strength application once per season or three times a year is more than sufficient. Only larger and more demanding varieties will need full-strength fertilization multiple times a year. 

For pellets or spikes, simply place them in the soil as the manufacturer recommends and let the fertilizer slowly reach the roots each time you water.

Key Considerations for Fertilizing Calathea

Key Considerations for Fertilizing Calathea

Over-fertilizing a Calathea is easy because this plant doesn’t need a lot of nutrients, especially when smaller or during the winter. 

The calathea plant will develop brown tips and may yellow down the centers of the leaves, losing color in the process. Unfortunately, this can also be confused for too much light or too little water. 

Excess fertilizer is often overlooked until the plant is badly shocked. Using a too strong fertilizer or that offers a slow-release may leave the plant struggling to survive. Removing the affected soil and replacing it entirely, rinsing the plant roots in the process, can help reverse the damage. 

Replacing the potting mix regularly is an excellent practice to keep salts from fertilizer and minerals from water from building up.


Fertilizing Calatheas FAQs:

Do Calatheas need fertilizer? 

Despite being less demanding than many other houseplants when it comes to fertilization, Calatheas need some nutrients regularly. The potting mix tends to run out of macronutrients after the first year of growth. After that point, a Calathea will likely need at least three doses of fertilizer per year.

When should I fertilize my Calathea? 

Only fertilize Calathea in the spring, summer, and fall when the plant is actively growing. Winter is time to break from feeding the plant, even diluted doses. Overfertilization is common if you try to fertilize on a schedule, so try watching the plant for signs growth is slowing or the colors are fading instead. Some smaller Calatheas may only need a single fertilization a year.

What is the best fertilizer for Calatheas? 

Any store-bought houseplant fertilizer with an NPK ratio of 3-1-2 is a good choice. Many common fertilizers are far more potent than this and must be diluted repeatedly to work well. Fish emulsions and kelp products are an excellent organic choice with the desired ratio and micronutrients for good color.

Is Miracle Grow suitable for Calatheas? 

With an NPK ratio of 24-8-16, Miracle-Gro does have the correct NPK ratio if diluted enough. Dilute the recommended dose eight times to reach the right level for Calathea. Diluting the mixture 16 times instead can reduce the chances of burning the plant, making the math even more complex. Starting with a different product with a lower NPK ratio is likely easier.

Are used coffee grounds good for Calatheas? 

Thanks to their mostly nitrogen composition, coffee grounds are a good DIY fertilizer for Calathea.


Wrapping Up

Calatheas are beautiful and need quite a bit of care and attention to thrive. To keep their colors bright and patterns bold, stick to only mild and occasional fertilization to avoid burned or browning leaves.


Author

I’ve long been fascinated with the world of flowers, plants, and floral design. I come from a family of horticulturists and growers and spent much of my childhood in amongst the fields of flowering blooms and greenhouses filled with tropical plants, cacti, and succulents from all over the world. Today, my passion has led me to further explore the world of horticulture, botany, and floristry and I'm always excited to meet and collaborate with fellow enthusiasts and professionals from across the globe. I hold a BSc degree in Plant Sciences and have trained professionally at leading floristry schools in London and Paris.

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