In this guide, we’re going to cover some soil basics and information that will help you choose the best soil mix for your Calathea plants. Also known as Prayer Plant or the Rattlesnake Plant, Calathea is relatively easy to take care of once the right soil mix is used. Since these plants need a lot of moisture but can be prone to root rot, soil drainage is the key.
- The Best Soil Mix for Calatheas – The Essentials
- Why Soil Choice Matters
- What are the Primary Components Used in a Potting Soil Mix?
- Common Signs You’re Using the Wrong Soil Mix for Calatheas
- The Importance of Well-Draining Potting Soil for Calatheas
- What pH Levels in the Soil are Best Suited to Calatheas?
- The Ultimate Calathea Plant Potting Mix Home Recipe
- The Best Pre-mixed Soils for Calatheas
- Soil Mix for Calatheas FAQs:
- Wrap Up
The Best Soil Mix for Calatheas – The Essentials
Calathea prefers loose and fast-draining soil with a neutral, slightly acidic pH of 6.5. Yet it also needs its potting mix to hold water since it prefers to stay slightly moist. Balancing bark and perlite is essential in the mix. Activated charcoal is also commonly added for pH balancing.
Why Soil Choice Matters
Many plant owners overlook the importance of soil, especially for container plants. Along with suitable light, temperature and humidity, watering schedules, and the occasional pruning, a proper soil mix is a key to steady growth and good health for mature or recently propagated Calathea plants.
Firstly, soil provides a place for the plant to anchor itself via good root growth. Not all houseplants develop deep roots, so the wrong mix could leave them tilting over under their own weight.
Secondly, soil provides both nutrients and water to the searching roots. If it holds water too well or is too high in nutrients, it can be just as bad for the plant as the opposite.
Finally, the soil must maintain these functions over a long period despite the constant effects of compaction and organic material breakdown.
In the ground, all soil is a combination of clay, sand, silt, and loam. These four ingredients vary in different amounts to produce almost any texture, including soils where rocks or chalk affect growth.
The mixes used for container plants like Calathea are made with different materials to control the texture and nutrient levels over time.
What are the Primary Components Used in a Potting Soil Mix?
Potting soil mix for containers is generally free of clay, although it may still contain sand or loam-like outdoor soil. Instead, most potting soil mixes contain all or some of the following ingredients.
- Compost, Loam, or Aged Organic Matter: The bulk of most potting mixes, these organic materials provide a fluffy texture that holds water and most nutrients.
- Sphagnum Peat Moss: Fluffier and lighter than even loam, peat moss keeps moisture in the soil as well.
- Pine Bark Fines: Cheaper than most compost or peat moss products, pine bark fines tend to have an acidic pH but drain very well.
- Coco Coir: Made from the fibers on the outside of coconut shells, coir is more renewable than peat moss but doesn’t hold water quite as well.
- Perlite or Vermiculite: Small white balls that resemble Styrofoam. These materials are actually expanded minerals. They keep the mix light and well-draining.
- Pumice: An excellent alternative to perlite or vermiculite popular for dry plant mixes for cacti and orchids. However, it’s harder to find at most nurseries.
- Rocks, Pebbles, Gravel, and Sand: Easier to find than any other drainage material, these various rock sizes can all help keep a potting mix well-draining. However, they can compact unless a mix of sizes is used.
- Soil Activators: Made from natural products known as humates, which help plants roots access nutrients and increase the water holding capacity of the soil.
Common Signs You’re Using the Wrong Soil Mix for Calatheas
Calathea plants prefer a specific type of potting mix. If they’re planted in the wrong soil mix in an indoor container, they may show particular signs of illness. Of course, most of these symptoms can be caused by other sources, so rule them out before changing the soil in the container.
- Slow growth: A lack of growth in Calathea over six months or more is likely due to compacted, depleted potting mix.
- Root rot: If the soil stays wet and the Calathea plant starts curling, yellowing, and losing leaves, it’s likely suffering from root rot. A lighter, better draining mix is the best fix.
- Lack of color and vibrancy: Some Calathea varieties are quite colorful or brightly variegated, but they’ll quickly fade to a bland light green or brown if the soil mix is incorrect. The leaves of your calathea plant may also start to droop or wilt.
- Reduced resistance to pests: Calathea are generally a pest-resistant houseplant, so if you get an infestation of aphids or whitefly, consider improving the soil mix as well.
The Importance of Well-Draining Potting Soil for Calatheas
Calathea needs a steady level of moisture and good drainage, which can be tricky to provide in a container. Balancing the moisture-holding and the drier materials in the mix is essential for this houseplant.
The mix will need both organic materials that act sponge-like, such as compost or aged pine fines. Nutrient levels should also be higher than other houseplants, but not from an added source like fertilizer. Using humates and compost or aged manure should be enough to introduce the necessary nutrients.
What pH Levels in the Soil are Best Suited to Calatheas?
A balanced pH level of around 6.5 is necessary for good growth. Calatheas can grow well in soil that measures 7.0 or 6.0, but they won’t be as healthy or grow as quickly.
Tracking the relative pH of each ingredient and following a trusted formula will ensure the right balance.
You can also use a pH meter on the finished mix, but you’ll need to have an expensive and sensitive meter for this to work. Basic home pH tests rarely reveal the true balance of a soil mix.
The Ultimate Calathea Plant Potting Mix Home Recipe
To create your own well-draining, nutrient-rich, loose, and supportive potting mix for your Calathea plants, mix:
- 25% aged bark – pine fines or orchid bark mix
- 25% coconut coir broken down into a fine fluff
- 25% perlite
- 15% activated charcoal, which holds water without waterlogging the soil
- 10% worm castings
Wet the coir and perlite first with warm water. Wear gloves and gently mix the combination, so it doesn’t become dusty or fly away. Once it’s well mixed, add the other ingredients and combine.
The Best Pre-mixed Soils for Calatheas
African Violet potting mix uses peat moss, but it offers nearly the same pH level and drainage while still holding plenty of moisture. However, a blend with orchid bark and charcoal will provide a better pH and resist compaction for longer. Calathea plants can also fare well in most general-purpose potting soils formulated for houseplants, such as:
- Bloomscape Potting Soil
- Dirtco. House & Tropical Plant Potting Soil
- African Violet Potting Mix
- Miracle-Gro Indoor Potting Mix
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Soil Mix for Calatheas FAQs:
How often should I switch soil for my Calathea?
Once a year or once every other year will provide the plant with good aeration and fertility.
Can I use cactus soil for Calatheas?
Cactus soil is often a little too dry for this moisture-loving plant. African Violet or moist orchid soil is a better blend.
Do Calatheas like wet or dry soil?
They prefer a steady supply of moisture and good drainage, making them right in the middle of the requirements.
What are the primary considerations for soil when repotting Calatheas?
Good drainage is essential, but the roots can’t dry out too quickly either. Use a balance of ingredients that hold water and shed it when repotting calatheas.
Does the size of the plant affect the soil mix for Calatheas?
No, Calatheas of all sizes needs the same mix.
Does the potting container influence the type of soil mix for Calatheas?
If the container is likely to hold water, stick with a drier potting soil like a cactus mix. Aim for more peat moss and coir if you suspect the container may dry out too quickly. Terra cotta pots help hold moisture, so aim for a drier mix for those containers.
Do Calatheas need deep potting containers?
Calathea doesn’t have particular deep root systems, but they do grow best in pots that are as tall as they are wide. Shallow pots will only cause them to stall out and dry up too quickly.
Prayer or rattlesnake plants are beautiful and easy to care for when potted in the right mix. As long as they’re getting enough light and receive a fresh dose of potting mix every year or so, Calathea should grow steadily. Potting mix and a regular supply of soil-based nutrients will help maintain the color of any variegated cultivars as well. Regardless of the specific Calathea species, you’re trying to grow, the same general soil mix should work well if refreshed regularly.
Andrew is the Editorial Director at Petal Republic. He holds a BSc degree in Plant Sciences and has trained professionally at leading floristry schools in London and Paris. In amongst overseeing a global editorial team, Andrew's a passionate content creator around all things flowers, floral design, gardening, and houseplants.