The short answer: coco coir works for orchids and anthurium as husk chips, not as fine coco peat on its own. Phalaenopsis does best in pine bark with 20 to 30% chips of the smallest grade, cymbidium and dendrobium take 100% medium chips or a chip-and-bark mix, and pot anthurium wants a capillary blend of pith or fibre with chips or perlite. Whatever you grow, the chips have to arrive low in salt or be rinsed until they are, because all four crops are salt-sensitive.
This article is about matching the material to the crop. For what husk chips are, size bands, general soaking steps and how long they last, see the coconut husk chips guide. For EC test methods and what washing does and doesn't remove, see buffered vs unbuffered coco peat. Neither is repeated here.
Chips, pith or a blend?
Orchids and anthuriums are epiphytes. Their roots live in air, so the medium has to stay open after months of watering. Fine coco peat alone packs down and holds too much water. Chips do the opposite, and a chip-heavy blend sits in between. The commercial pot-anthurium target is a useful yardstick for both crops: about 50% solids, 25% water and 25% air by volume, with enough fine particles or fibre to move water through the pot but not so much dust that the base clogs.
| Medium | Water holding | Air when wet | Useful life in a fed, watered pot | Salt on arrival | Nitrogen tie-up | Best fit |
|---|---|---|---|---|---|---|
| Coco husk chips (100%) | Medium. Each chip is a sponge, gaps between chips drain fast | High | 1 to 2 years. Faster if kept constantly wet and fed | Sodium, potassium and chloride. Must be rinsed or bought low-EC | Low. Mostly lignin, balanced feed is fine | Cymbidium, dendrobium, cattleya alliance, vanda, mature anthurium |
| Chip/pith blend (e.g. 70% chips, 30% pith) | Medium-high, capillary | Medium | 1 to 2 years | Same as chips. Pith rinses more easily than chips | Low | Pot anthurium, aroids, small-pot orchids in dry air |
| Pine bark | Low when fresh, rises as it ages and breaks down | High | About 2 years. Flat flaky bark breaks down faster than rounded bark | None | High. Decomposing bark can leave no detectable nitrate in the pot | Phalaenopsis base, paphiopedilum, phragmipedium, anything you tend to overwater |
| Sphagnum moss | Very high. Holds up to 20 times its weight | Low once compacted | About 1 year. Separates and shrinks, especially short fibre | None | Low | Young plants, plug stage, dry climates, growers who water sparingly |
Two points from that table drive everything below. Chips hold more water than bark and less than sphagnum, so a grower moving from bark to chips waters less often. And chips are the only one of the four that arrives with salt.
Chip grades and when to use each
Suppliers use names like small, medium and large, and the millimetre bands behind those names differ from one supplier to the next. Order by millimetre range.
| Grade | Typical band | Use it for |
|---|---|---|
| Fine | 5 to 8 mm | Blending into pith for anthurium pots and small orchid pots. Not alone: too wet |
| Small | 6 to 12 mm | Phalaenopsis (as 20 to 30% of a bark mix), 9 to 12 cm pots, seedlings moving out of plugs |
| Medium | 12 to 18 mm | Cymbidium, dendrobium, cattleya, anthurium top-up, 14 to 17 cm pots |
| Large | 18 to 25 mm and up | Vandas, baskets, big cymbidiums, drainage layer in deep pots |
Three rules of thumb. Match chip size to pot size, because a small pot has a small moisture buffer and dries out fast, so it wants a finer grade than a big pot. Keep the pieces in a mix roughly the same size as each other so they don't separate when you pot up. And remember that small chips give up salt faster than large ones in the rinse tank. Rinsing large fractions completely is close to impossible, which is one reason phalaenopsis growers use the smallest grade.
Phalaenopsis
Phalaenopsis has no pseudobulbs, so it can't ride out a dry spell, but its roots also rot fast if they sit wet. The European pot-plant standard is pine bark of the two finest fractions plus 20 or 30% coco chips of the finest fraction, with coconut making up anywhere from 10 to 50% of the volume depending on the grower. Pure bark holds too little water for a bare-root transplant, so something has to go in with it. Chips are the stable option. Sphagnum works too, but it separates out of a bark mix within months and only about 1.5 to 2 kg per cubic metre is used.
Can you grow phalaenopsis in 100% coco? Yes, if the salt balance is controlled, and some growers do. The caveat is that in a controlled eight-media comparison, the mixes containing husk chips gave smaller plants with fewer spikes than the 70% bark / 30% coarse peat control. That doesn't rule chips out at 20 to 30%, but it argues against going all-coco on a crop you sell by spike count.
Watering. In a bark mix in a hot climate, a 15 cm pot needs water every five to seven days and a 10 cm pot every four to five. With 30% chips in the mix, stretch that out, and never let the pot dry right through. At each watering, put on enough for 20 to 30% to run out of the bottom. That's your salt control.
Repotting. Bark-based phalaenopsis media are usually replaced about every two years, sooner if fine particles start washing out of the drainage holes. Commercially the substrate has to hold its structure for about a year, the length of a plug-to-flower cycle. Repot in late winter or early spring when new root tips show.
Cymbidium
Cymbidium is the orchid that likes chips most. Thick roots, big pots, a heavy plant that needs anchoring and a medium that must stay open for two to three years between repottings. Growers who trialled pure coco husk reported their best results with cymbidiums: healthy roots throughout, even on divided back-bulbs, and no visible deterioration of the medium after 18 months.
Use medium or large chips, alone or with bark. One grower who added 20% perlite found it made no difference to growth and roughly doubled the cost of the mix, so dropped it. For a bark-based cymbidium mix, allow about six weeks of composting with a nitrogen source before potting so the bark isn't drawing nitrogen from the plant. Chips don't need that step.
Water less often than you would in bark. The simplest check is a plant-free control pot of the same chips in the same place. Tip it out and look at the bottom before you water the batch.
Dendrobium
Dendrobium is a large genus and the answer splits by type. Hard-cane and evergreen types grown warm do well in medium chips, and a trial on the cut-flower hybrid Sonia 17 ranked coconut husk chips with brick pieces, charcoal and gravel at 2:1:1:1 top of ten media for root count, spikes per plant (3.58 a year) and vase life (nearly 16 days). The inert components keep the mix open as the chips age.
Soft-cane and cool-growing types, and the Australian native species, are the ones to watch. Growers reported those staying wet too long in pure coco husk over winter. For them, cut the chips with bark or inert material, use a larger grade, and water very sparingly in the cold months. Keikis on soft-canes rooted well in chips, so the material isn't the problem, the winter water is.
Anthurium
Pot anthurium is grown commercially in 9 to 17 cm pots over roughly six to nine months from plug to sale. The standard Dutch substrate is peat with coconut fibre, often with coconut chips, perlite or fine bark added. The fibre is there for capillarity, since water put on from below has to travel up the pot. The chips are there for air. Even sub-irrigated crops get watered from above every four to six weeks so the top layer doesn't go dusty.
A peat-free version of that recipe is coco pith plus fibre plus chips, which is where a custom chip/pith blend earns its place. The Caribbean cut-flower practice is older and simpler: husk cut into roughly 2.5 cm pieces, used alone in raised beds, topped up every year, pH held near 5.5 with calcium carbonate. In a two-year Indian greenhouse trial on the pot variety 'Tropical', coconut husk and charcoal at 3:1 led the other media for height, leaf area and flower count, at about eight flowers per plant.
Targets worth copying. Start the substrate at a pH of about 5.5 and an EC around 0.5 mS/cm. Feed at an EC of 1.8 to 2.4 overhead or 1.8 to 2.2 on drip, and rinse with low-EC water after any overhead application above 1.0. Keep sodium and chloride in the irrigation water below about 4 mmol/L (91 mg/L). Those limits are tighter than most vegetable crops, and they're why coir for anthurium has to arrive clean.
Washing, EC and the salt question
All four crops show salt damage the same way: brown root tips, dead leaf tips, slow growth after repotting. Raw husk chips can carry thousands of ppm of dissolved salt. One orchid grower measured over 10,000 ppm in a first batch and needed several weeks of repeated soaking to bring it under 20 ppm. That's the extreme end, but it shows why "orchid grade" has to mean a number, not a label.
Low-EC supplier grades are typically quoted at 0.4 to 0.7 mS/cm, some at under 1.0, and the extraction method changes the figure. Even pre-washed chips are worth one overnight soak to clear dust and tannins. Unwashed chips need three soaks with the water changed, and a check of the last rinse against your tap water. Pith in an anthurium blend rinses faster than chips but holds potassium and gives up calcium and magnesium, so feed both and watch young leaves for calcium deficiency in the first months.
Washed coco peat from CVM Fiber and Industries in Kanyakumari, Tamil Nadu, India is rinsed with water to reduce EC and isn't treated with calcium nitrate or other chemicals, so buffering stays in the grower's hands. The soaking steps and the washed-versus-buffered question are covered in the two articles linked at the top.
What to specify when buying for a nursery
A hobby grower can rinse a brick in a bucket. A nursery potting thousands of 12 cm phalaenopsis can't, so the specification has to do the work. Put these on the purchase order:
- Chip size in millimetres with a maximum fines percentage. "Medium" is not a spec.
- EC with the extraction method named (1:1.5 volume, 1:5, saturated media extract or pour-through) and the maximum you'll accept. For these crops most buyers ask for washed material at or below 0.5 mS/cm on a 1:1.5 extract.
- Sodium and potassium in the same extract. EC alone doesn't say which salts are left.
- pH range, and whether you want a lime buffer (about 2 to 3 kg per cubic metre is the anthurium norm) mixed in or left to you.
- Moisture content of the compressed product, usually 15 to 18% or below 15%, and expanded volume per block.
- Blend ratio by volume for chip/pith or chip/fibre mixes, plus the chip grade used.
- A retained sample from the batch you'll receive. Coir varies with husk source and processing, and these crops don't forgive a salty batch.
CVM supplies graded coconut husk chips and chip/pith custom blends for nursery use. If you grow orchids or anthurium at scale, send us your chip grade, blend ratio and EC limit and we'll quote against them.
FAQ
Can I grow orchids in coco coir instead of bark?
Yes, as husk chips rather than fine coco peat. Cymbidium, dendrobium, cattleya and vanda do well in pure chips or chip-and-bark mixes. Phalaenopsis is usually grown in bark with 20 to 30 percent small chips. Paphiopedilum and phragmipedium have done worse in coco than in bark for several growers, so trial a few plants first.
Is coco coir good for phalaenopsis?
As a component, yes. The standard commercial mix is fine pine bark with 20 to 30 percent of the finest coco chip grade, which holds more water than bark alone without going soggy. Growing phalaenopsis in 100 percent coco is possible if salt is controlled, but in one controlled comparison all-chip mixes gave smaller plants with fewer spikes than a bark and peat mix.
What size coco chips for orchids?
Match the chip to the pot. Use 6 to 12 mm chips for phalaenopsis and pots up to about 12 cm, 12 to 18 mm for cymbidium, dendrobium, cattleya and 14 to 17 cm pots, and 18 to 25 mm or larger for vandas, baskets and big cymbidiums. Smaller chips hold more water and rinse free of salt faster.
Coco chips or bark for anthurium?
Neither alone. Pot anthurium wants a capillary blend, so commercial growers use peat or coco pith with coconut fibre and add chips, perlite or fine bark for air. Aim for roughly half solids, a quarter water and a quarter air by volume. In cut-flower beds, husk pieces of about 2.5 cm are used on their own and topped up yearly.
Do pre-washed coco chips still need soaking?
Give them one overnight soak before potting to clear dust and tannins, then pot them damp. Unwashed chips need at least three soaks with the water changed each time, and a check of the final rinse water against your tap water. Phalaenopsis and anthurium are salt-sensitive enough that an extra rinse is cheap insurance.
How often should I water orchids in coco chips?
Less often than in bark, because each chip holds water like a sponge. In a hot climate a bark-potted phalaenopsis in a 15 cm pot needs water every five to seven days, so with chips in the mix expect to stretch that. Keep a plant-free control pot of the same chips and tip it out to check the bottom before watering, and let 20 to 30 percent of the water run through each time to leach salt.
How often do orchids in coco chips need repotting?
Plan on one to two years for phalaenopsis and two to three for cymbidium, the same brackets as bark. Chips kept constantly wet and fertilised can collapse within a year, while chips on a drier regime have shown no deterioration at 18 months. Repot when the mix softens and stays wet much longer than it used to, not on a fixed date.
What EC should coco chips be for orchids and anthurium?
Ask for washed material and a stated test method. Low-EC supplier grades run about 0.4 to 0.7 mS/cm on a 1:1.5 volume extract, and 0.5 or below is the common target for these crops. Anthurium growers start the pot at about 0.5 mS/cm and pH 5.5. Any figure quoted without the extraction method can't be compared between suppliers.