My Alocasia Soil Mix: Coco Coir + Perlite

My mix, in 45 seconds

My two coco + perlite recipes

Choose either example batch above: they make different amounts with the same proportions. You can also use a cup, scoop or container of any size — use the same measure for both ingredients. For a larger 50/50 batch, 1 US gallon of each works too.

Measure by volume, not weight, using hydrated, drained, loosely filled coco. A dry compressed brick is not a measuring unit. Mix the ingredients evenly without pressing them into a dense block.

I use more perlite in self-watering systems because water is supplied from a reservoir. In a regular pot, the higher coco proportion gives the mix more moisture storage between waterings. These are my starting recipes; pot size, wick design, light and root development still affect how wet the mix stays.

Choose horticultural coco coir, often sold as coco peat or coir pith, with a loose, crumbly texture. Large coconut chips and long coir matting behave differently. I always use buffered coco, either prepared by the manufacturer or buffered before planting.

From coco brick to finished mix

A closer look at my preparation, captured from my own mixing video.

These photos show hydration and mixing. Adding water does not buffer coco: use ready-buffered coir or complete the separate rinse-and-buffer process below before making your mix.

Why washing and buffering are different

Raw coco can contain unwanted soluble salts, including sodium and chloride, as well as substantial potassium. Washing carries soluble salts away with the drainage water. It also removes loose dust and excess fines. Fine coir pith is a useful part of the substrate, though: the aim is a suitable horticultural texture, not removing every small particle. RHP explains coir processing.

Coco also has tiny negatively charged sites that hold positively charged nutrients. Think of them as parking spaces. Calcium and magnesium can attach there while potassium and sodium move into the water. In untreated coco, this can change the nutrient balance around the roots after you feed.

Buffering lets that exchange happen before the plant goes in. A calcium-and-magnesium soak conditions the coco, and draining removes the spent solution. It does not make coco chemically inactive forever, provide a complete fertilizer or permanently fix its pH. RHP: nutrient exchange and pH; CANNA: growing with coco.

A “washed” or “low EC” label does not, by itself, mean “buffered.” EC is electrical conductivity, an indicator of dissolved salts — here’s how to measure it. For a product clearly sold as washed, buffered and ready to use, follow its preparation instructions; an extra strong soak is not automatically necessary.

EC, explained without the chemistry lesson

EC means electrical conductivity: how easily a liquid carries an electric current. Dissolved salts release charged particles that conduct electricity. Fertilizer adds these particles, but so do minerals already in your tap water and salts washed out of coco. A higher EC generally means more dissolved salts. Think of it as a quick check of the solution’s overall strength, not a breakdown of its ingredients. Hanna Instruments explains EC.

That matters because excess salts can make it harder for roots to take up water. EC helps you compare your starting water, mixed solution and drainage water. It cannot tell you how much calcium or magnesium is present, whether nutrients are balanced, or whether coco is fully buffered. EC and pH are separate measurements: pH tells you how acidic or alkaline the solution is.

These are equivalent displays of the source method’s buffer-bath range, not four different recipes or routine feeding targets. Other ppm conversion factors exist; do not guess yours. Bluelab explains EC and ppm scales.

If you want to check EC: choosing a meter

A small handheld EC meter, often sold as an “EC/TDS water tester,” is enough for liquid samples. Basic pens can cost around US$10; prices vary by model and country. For a price reference, VIVOSUN lists a basic EC/TDS pen at US$9.99. You can also search Amazon for “EC TDS meter.” Look for an actual EC display in µS/cm or mS/cm, automatic temperature compensation (ATC), and instructions for checking its accuracy. A soil moisture probe does a different job.

How to take a reading

1. Check the meter. Use the conductivity standard specified in its manual; calibrate if the model allows it. A low price does not tell you whether its readings are accurate.
2. Measure your starting water. Put a sample in a clean cup. Rinse the probe as instructed, select EC mode and immerse the sensing tip to the marked depth. Let the temperature and reading settle, then note the number and units.
3. Mix, then measure again. Add the measured product dose to your water, mix thoroughly and test a fresh sample. For runoff, collect fresh drainage in a clean container; a liquid EC pen goes in this sample, not into the coco.
4. Rinse after use. Clean and store the meter according to its manual. Use the same sampling method when comparing readings over time.

Meter care and measurement: Bluelab’s conductivity-pen instructions; Hanna on checking calibration.

How to prepare unbuffered coco

This is a concise adaptation of the double-soak method I follow, applied here to preparing substrate for houseplants.

1. Hydrate and rinse. Expand the brick in water, loosen it, then rinse through a strainer.
2. Mix a fresh buffer bath. The source specifies at least 7.5 mL CALiMAGic per US gallon (3.785 L), approximately 2 mL/L, with EC 1.2–2.0 mS/cm and pH above 6.2. These are bath conditions, not routine feeding targets.
3. Soak for at least 8 hours. Hold the coco in a fabric pot or permeable bag, fully submerged.
4. Drain and repeat. Remove the used solution. Prepare a fresh bath and submerge the coco for another 8 hours or longer.
5. Drain, then mix in perlite. Let the used buffer solution drain away before making your mix.

The quantities are per volume of water, not per litre of coco. Prepare enough to keep it submerged. Each soak needs fresh solution.

Dosing and checking are different steps. The original method also recommends checking runoff EC before planting, then rinsing if excess salts remain and applying an appropriate nutrient solution. You can measure out the recipe without an EC meter, but the calculator cannot perform that final salt check or confirm that coco is fully buffered. EC does not measure calcium or magnesium individually, and neither EC nor pH can be verified from the calculated dose alone.

Why I choose coco for my Alocasias

I like a soft, loose medium that surrounds the roots while holding moisture. Coco’s fine structure creates many small water-holding spaces; perlite helps keep the blend open. The useful combination is accessible moisture with room for oxygen, rather than softness alone. Oklahoma State: growing media properties.

Coir also takes up water readily after drying. That helps with rewetting, but it does not mean roots are protected if the whole pot becomes bone dry. RHP: water retention and rewetting.

What about delicate root hairs?

Root hairs increase contact with the surrounding medium. Research in maize found that they can shrink early as soil dries, reducing that contact. This supports paying attention to moisture around fine roots; it does not establish that coco protects Alocasia roots better than every other substrate. Study in Plant Physiology.

My practical reason for choosing coco is the moisture-holding material around the roots. Air spaces themselves are healthy: roots need oxygen. The goal is to avoid both excessive drying and prolonged waterlogging.

How coco compares with other growing media and setups

LECA can grow excellent roots in a well-managed system. Coco is my preference for this setup, not proof that pebbles damage roots. And when I say moss here, I mean long-fibre sphagnum, not a peat-based potting mix. Oklahoma State on coco and LECA; American Orchid Society on moss and watering.

Why I don’t choose LECA-and-moss vases for long-term growing

I mean a vase with no drainage holes, with LECA at the bottom and sphagnum moss above it, planted directly into the vessel. I agree that these setups can give good results at first, including impressive root growth. My concern is how easy they are to maintain later.

For me, the biggest drawback is flushing. As roots fill the gaps and form a dense mass through the moss and LECA, I find it increasingly difficult to rinse the whole medium and remove the old water. Once the vase is tightly packed with roots, doing that thoroughly without disturbing the plant can feel almost impossible.

Water and fertilizer can bring in dissolved salts. As water is lost and plants take up nutrients at different rates, some salts can remain and accumulate. Simply topping up the vase does not remove those leftovers. Excess salts can damage roots and contribute to slower growth, wilting or brown leaf tips, although these symptoms can also have other causes. University of Maryland explains salt injury and leaching.

A vase system can work when water quality, feeding and solution replacement are managed. For my routine, being able to rinse the mix and remove old solution easily matters more than a strong start.

Why chunky mixes didn’t suit me

Chunky mixes didn’t give me the consistency I wanted with my Alocasias. I found a mix of different organic ingredients harder to keep predictable, particularly when thinking about what was happening around the roots and the risk of rot. With buffered coco and perlite, I have a simple recipe I can repeat, and I choose the nutrients I add.

Organic ingredients change over time, and their stability and biological activity matter. Bark can be a useful source of air spaces; its presence does not automatically make a mix prone to rot. Coco is also an organic material, and buffering does not sterilize it. Microbes can live in either medium. My advantage with coco is a setup I find easier to manage, rather than complete control over every microorganism. RHP explains biological activity and substrate stability.

Why I don’t use ordinary potting soil for my Alocasias

Of the options I’ve tried, ordinary all-purpose potting soil has worked worst for my Alocasias. The mixes I used were too dense for my setup. I prefer the loose texture and adjustable coco-to-perlite ratio of this recipe.

Roots need oxygen as well as moisture. When a fine mix stays saturated, water fills the spaces that would otherwise hold air. Prolonged wet conditions can stress roots and favour root-rot diseases. The same problem can occur in coco if the mix and watering system keep it too wet. University of Minnesota explains conditions that favour root disease.

That is my experience with the products and conditions I’ve used, not a verdict on every bagged mix. Store-bought blends differ: some already contain plenty of bark or perlite, while others are much finer. Oklahoma State explains how potting mixes differ. For my home and watering routine, buffered coco plus perlite is the combination I find most predictable.

Feeding and watering after planting

Choose a complete fertilizer suitable for coco

Coco and perlite are a growing medium, not a complete food supply. Coco can hold and release nutrient ions, so the balance in the root zone can differ from what you pour in. A complete coco-specific fertilizer is a straightforward choice because it is formulated for those interactions. An appropriately balanced hydroponic formula can also work when its suitability for coco and your water is confirmed. Ordinary houseplant fertilizer is not automatically interchangeable. CANNA explains coco’s nutrient requirements.

Check for the full nutrient range, including calcium, magnesium and micronutrients. Do not automatically add extra Cal-Mag on top: the base fertilizer and your water may already supply enough. Use a feeding strength suited to the plant and growing conditions; the buffer-bath concentration above is a separate preparation step. CALiMAGic is a supplement, not a complete base fertilizer.

Give water somewhere to go

In a regular pot, water through the mix and let excess drain. With a self-watering pot, follow the system’s reservoir limit and wick instructions, and check that moisture actually reaches the roots. A pot standing in water is not automatically a well-designed self-watering system.

As water evaporates and plants take up nutrients at different rates, soluble salts can accumulate. Periodic top-watering with drainage and replacing reservoir solution can help manage that buildup. Remove the old runoff rather than returning it to the reservoir. Frequency depends on your water, fertilizer and system; use their guidance and monitor the mix instead of following a universal weekly schedule. AOS on salt buildup; CANNA on monitoring coco.

Check moisture below the surface and notice changes in pot weight. A dry-looking top can hide a wet lower zone. Keep light, pot size and watering in balance with the plant’s growth.

Is this hydroponics or semi-hydro?

Soilless growing is the clearest description. When a complete nutrient solution feeds roots supported by coco and perlite, it is substrate-based hydroponics. Hydroponics can use a solid growing medium; roots do not have to sit in open water. A reservoir-and-wick setup is a form of passive irrigation often called semi-hydro by houseplant growers. Oklahoma State’s definition of hydroponics.

The connection to Dutch horticulture

Coco is used in professional horticulture, including systems supplied by Dutch substrate producers. Dutch Plantin prepares coir for growbags, pots and hydroponic applications, tailoring its components to the crop. Wageningen University’s root-zone work emphasizes matching the substrate with irrigation, nutrition and the balance of water and air. Dutch Plantin’s production process; Wageningen RootzoneLab.

The lesson for a houseplant grower is to treat the mix, fertilizer and watering system as one setup. My 50/50 and 70/30 recipes are how I put that idea into practice at home.