Sphagnum moss holds more water than coco coir, stays very acid and is still the standard for young Phalaenopsis, carnivorous plants and air layering. Coco coir is cheaper, less acid, more uniform from batch to batch and doesn't come from wild bogs. For most orchids, cuttings and liners the choice is about how much water the plant wants at the root and how often you can water. Where moss is the default, coir usually works best as a partner rather than a straight swap.
First, a point that confuses a lot of buyers. Sphagnum moss is the dried top growth of living Sphagnum plants, sold as long strands. Sphagnum peat is the same plant after centuries of partial decay in a bog, sold as a fine brown medium. This article is about the moss. For peat, see coir vs peat.
Side by side
| Coco coir | Long-fibre sphagnum moss | |
|---|---|---|
| Source | Coconut husk, a crop by-product | Wild or managed bogs, mainly New Zealand and Chile |
| Water held | 7.5 to 11 times its dry weight (fine pith) | Up to about 20 times its dry weight |
| pH | About 5.6 to 6.9 | Low. Root zones in moss pots can fall to around pH 3 after a few months |
| Salts on arrival | Sodium, potassium and chloride unless washed | Very low |
| Structure | Fine pith, or chunky chips. Doesn't knit together | Long strands that wrap round roots and hold a plug together |
| Breakdown in a pot | Slow. Chips last one to two years in orchid pots | Faster. Compacts and needs replacing in about one to two years |
| Batch consistency | Depends on the supplier's washing and grading | Varies with origin. New Zealand moss is generally rated higher than Chilean |
| Disposal | Compost | Compost |
Orchids
This is where the comparison matters most. Pure sphagnum is widely regarded as the single best medium for young Phalaenopsis in warm climates. Taiwan, the largest exporter of Phalaenopsis, grows nearly all of its plants in moss. Plants come out of flask into plug trays of moss and often stay in it right through to sale.
Moss works because it holds a lot of water and nutrients and keeps them close to the roots. It has two downsides. Roots in moss tend to stay inside the pot rather than climbing out, which suits a plug grower but can mean wet roots in a big pot. And consumers often overwater plants sold in moss, which leads to root rot. That's one reason many growers in cooler, northern climates avoid moss-based media for finished plants.
Coconut husk chips have been compared with moss for Phalaenopsis many times. The results are mixed:
- In direct comparisons, moss usually wins on flowering. Plants in moss have flowered earlier and with more spikes than plants in coconut husk chips or chunks.
- Mixes with a lot of coconut chips have produced fewer spikes and flowers than standard bark or moss mixes.
- Where coconut husk was tested as a cheap tropical substitute for rockwool and bark, growth was similar, and husk was judged a good option on cost and availability.
- Coir blended partly with sphagnum has produced more leaves and heavier plants than pure moss.
So a blend is often the useful answer. Coir or chips add bulk, slow the breakdown and cut cost, while moss keeps the water reserve that young plants need. Grade choice and mixes for each orchid type are covered in coco coir for orchids and anthurium.
Carnivorous plants
Sarracenia, Venus flytraps and most Drosera want acid, nearly mineral-free media. Sphagnum moss or peat suit them naturally. Coir starts higher in pH and carries salts unless rinsed hard, so it's a poor main medium for bog plants. Rinsed husk chips do have a place in airy Nepenthes mixes alongside moss. Details are in coco coir for carnivorous plants.
Propagation and cuttings
Both work for rooting cuttings, but they behave differently:
- Air layering. Moss is the standard. Its long strands wrap round a wounded stem and stay put inside the plastic wrap. Loose coir pith falls apart unless bound tightly.
- Leaf and stem cuttings in trays. Coir pith holds plenty of water and stays well aerated if you use a medium grade. It's cheaper per tray and more uniform than chopped moss. See coco coir for rooting cuttings.
- Plugs and tissue culture plantlets. Moss holds a plug together before roots fill it. Coir pith needs a binder, a fibre fraction or a mesh sleeve to do the same.
- Water-loving cuttings in dry rooms. Moss stays moist longer. In humid propagation with misting, its water holding can be too much, and coir is easier to manage.
Hanging basket and wall liners
Sphagnum moss was the traditional basket liner. It looks natural, holds water and lets you plant through the sides. Coir liners are now the common choice because they're pressed or needled into shape, last a season or more, and don't depend on bog harvests. Moss still has fans for the look, but it dries quickly at the edges and needs repacking. The practical side of coir liners is covered in coir hanging basket liners.
How sustainable is sphagnum harvesting?
Sphagnum moss is a renewable crop in principle. It regrows from the living layer left behind. Whether it's harvested sustainably depends on how much is taken and how long the bog rests.
New Zealand. Most moss comes from the West Coast of the South Island, from bogs, swamps and cutover forest. Harvesting grew into an export industry worth millions. Regrowth depends on leaving some moss behind. In replicated plots on a New Zealand bog, areas where 30% of the harvestable moss was left had regained 90% cover after three years. Fully harvested plots reached only 50%. Reseeding also speeds recovery.
Chile. Large-scale harvesting for export to Japan, South Korea, Taiwan and the United States took off in the 2010s. Since 2018 Chilean rules allow only hand harvesting with pitchforks or similar tools, require at least 30% of the moss cover in each harvest area to be left, and keep the remaining moss at least 5 cm above the water table. The same plot can't be harvested again for 12 years in the northern regions of Los Ríos and Los Lagos, or for 85 years in Aysén and Magallanes further south. Concern remains that overharvesting affects the water these bogs store and release in dry months.
What that means for a buyer:
- Moss from well-run harvests regrows, but slowly. Rest periods are measured in years to decades.
- Origin and harvest practice matter more than the word "sustainable" on a bag.
- Coir doesn't raise these questions. It's a by-product of coconuts grown for food, though it has its own footprint from washing, drying and shipping.
A handling note
The fungus that causes sporotrichosis lives on plant matter, including sphagnum moss, rose bushes and hay. Infection usually follows a scratch or cut. Wear gloves and long sleeves when handling moss in quantity, especially when packing pots or liners by hand.
Choosing between them
| Use | Better choice | Why |
|---|---|---|
| Phalaenopsis plugs and young plants | Sphagnum moss | Highest water reserve, holds a plug together |
| Finished Phalaenopsis for retail | Bark, or bark with coir chips | Less risk of buyers overwatering |
| Cymbidium, dendrobium, anthurium | Coir chips or chip/pith blends | Slow breakdown, good air, lower cost |
| Sarracenia, flytraps, bog Drosera | Sphagnum moss or peat | Acid, mineral-free |
| Nepenthes | Moss with rinsed husk chips | Moisture plus air |
| Air layering | Sphagnum moss | Wraps and holds |
| Tray cuttings | Coir pith | Uniform, cheaper, well aerated |
| Basket liners | Coir | Holds shape, lasts longer |
CVM Fiber and Industries, in Kanyakumari, Tamil Nadu, India, supplies coconut husk chips, 650 g briquettes and 5 kg coco peat blocks. The coco peat is washed with water to reduce EC, with no calcium nitrate or other chemicals added. To discuss a chip size or blend for orchids or propagation, get in touch.
FAQ
Can I use coco coir instead of sphagnum moss for orchids?
For many orchids, yes, as coconut husk chips or a chip and pith blend. For young Phalaenopsis plugs, moss still tends to give better growth and earlier flowering. A blend of coir and moss is a good compromise.
Is sphagnum moss the same as peat moss?
No. Sphagnum moss is the dried top growth of living moss, sold as long strands. Sphagnum peat is the partly decomposed moss dug from deep bog layers. They behave differently in a pot.
Which holds more water, coir or sphagnum moss?
Sphagnum moss. It can hold up to about 20 times its dry weight in water. Fine coir pith holds roughly 7.5 to 11 times its dry weight.
How long does sphagnum moss last in a pot?
Usually one to two years before it compacts and stays too wet. Firmly packed moss dries more slowly than loosely packed moss. Coconut husk chips break down more slowly than moss.
Is sphagnum moss harvesting sustainable?
It can be, if part of the moss is left to regrow and bogs are rested. Chile requires 30% of the moss cover to be left and rest periods of 12 to 85 years depending on region. Overharvesting damages bogs and the water they store.
Is coir good for air layering?
Loose coir pith is awkward because it falls apart. Sphagnum moss wraps around the stem and holds together. If you use coir, bind it firmly in plastic or mix it with some moss.
Is it safe to handle sphagnum moss?
Wear gloves and long sleeves. The fungus behind sporotrichosis can live on sphagnum moss and other plant matter and enters through small cuts in the skin.