The short answer: a coco coir disc is a flat puck of dried, compressed coir pith that swells into a plug-sized cylinder of growing medium when you add water. "Coin", "pellet", "disc" and "plug" are mostly trade names for the same idea: netted pellets hold their shape with a mesh sleeve, bonded plugs use a binder, and bare discs have neither and are dropped straight into a pot or cell. They ship and store as dry discs, hydrate on the bench in minutes, and are transplanted whole, so roots are never disturbed. The decisions that matter for a nursery are size, netting or binder, EC of the coir, and whether a starter charge is included.
Key facts
- Jiffy's pellet range expands to 20–75 mm diameter and 35–190 mm height; its coir pellets (Jiffy-7C) are specified at pH 5.7 ±0.5, EC 0.9 ±0.4 mS/cm and 95–97 % coir pith by volume (Jiffy Pellets brochure).
- One Indian exporter lists plain coir discs at 30–100 mm diameter, 5–25 mm thick, expanding "5 to 7 times" on wetting (seller listing).
- In short propagation cells, peat held 65 % water and 11 % air by volume at container capacity, rockwool 87 % and 5 %, phenolic foam 91–93 % and 5–7 % (Yafuso, Fisher, Bohorquez and Altland, 2019).
- Jiffy switched its pellet nets from PE and PP plastics to PLA, certified compostable under controlled industrial conditions to EN13432; many other netted pellets still use synthetic mesh (Jiffy Group).
- Compressed pellets store for up to two years and take about a quarter of the inventory space of loose-filled trays (Jiffy Pellets brochure).
What coir discs, coins, pellets and plugs are
All of these products start with coir pith (coco peat), the spongy material between the fibres of the coconut husk. The pith is screened, often washed to lower its salt content, dried and pressed into a flat disc. Water releases the compression and the disc expands upward, roughly keeping its diameter and gaining height, so a disc a few millimetres thick becomes a cylinder several centimetres tall.
The names map onto three constructions:
| Type | Construction | Typical use |
|---|---|---|
| Netted pellet (Jiffy-7C style) | Compressed coir inside a fine mesh sleeve that stretches as the disc swells; usually a pre-formed dibble hole on top | Seed and cutting propagation in open trays or automated sticking lines; transplanted with net on |
| Bonded plug | Coir, sometimes with peat or biochar, held together by a binder; sold dry-compressed or pre-moistened | Cuttings and seed in hydroponics and cannabis propagation; often buffered and pre-charged |
| Bare disc or coin | Compressed coir only, no net or binder | Dropped into a pot, cell or microgreen tray and hydrated in place; also sold as "pot fillers" sized to the container |
Jiffy describes its netted pellets as "an open-wall, net container and medium in one"; its coir version, the Jiffy-7C, is 95–97 % coir pith by volume with the balance a starter fertiliser charge. Botanicare's CocoPro plug is a dry-compressed blend of "coco fiber, pith, and husk"; FloraFlex's Incubator plug combines coir, peat moss and biochar. Eazy Plug products are bonded plugs that retailers describe as having a buffered pH and EC and a fertiliser charge for the first two to three weeks. Bare discs are the simplest to make and come in the widest size range.
Sizes and expansion
Published size data is sparse outside the large brands, and figures from sellers are marketing claims rather than test results. The examples here are attributed so you can judge them.
| Product (source) | Dry size | Expanded size | Notes |
|---|---|---|---|
| Jiffy pellet range (Jiffy Pellets brochure) | Flat disc | 20–75 mm diameter, 35–190 mm height across all pellets; coir Jiffy-7C 20–60 mm diameter, 35–150 mm height | Netted; bulk density 0.085–0.095 g/cm³ for coir versions versus 0.15 for peat |
| Jiffy-7C 50 mm (Garden City Plastics listing) | Flat disc | 50 mm wide, 42 mm high | 20 × 40 mm pre-formed cutting hole; 560 per carton |
| Plain coir discs (Indian exporter listing) | 30–100 mm diameter, 5–25 mm thick | "Expands up to 5 to 7 times when watered" | pH quoted as 5.5–6.8; EC "low EC or washed as per requirement" |
Expansion is mostly vertical: a 50 mm Jiffy-7C ends up 50 mm across and 42 mm tall. Coir pellets are lighter than peat pellets of the same size (0.085–0.095 versus 0.15 g/cm³ in Jiffy's figures). And the "5 to 7 times" that exporters quote is a volume claim, not a height; in an unconfined disc some expansion goes sideways and is lost as crumbs. For filling whole trays rather than single cells, see the 650 g briquettes.
How to use coir discs and pellets
The method is the same for seed and cuttings; only the dibble depth differs.
1. Hydrate
Set the discs in a watertight tray, dibble hole up. Add warm water and wait until the pellets reach full height and the tops are soft; small pellets take a few minutes, larger discs longer. Pour off standing water. If the pellets carry no fertiliser charge, hydrate with your starting solution instead of plain water: the Root!t propagation guide has growers presoak plugs at pH 5.5–6.5 in a quarter-strength seedling feed, then "squeeze to release excess moisture". For large runs, Jiffy's expander wets up to 800 pellets a minute.
Plain discs without a charge are where incoming EC matters most. Coir dust from different sources measured 0.3 to 2.9 mS/cm in Evans, Konduru and Stamps' 1996 survey, and a seedling sits in a few millilitres of that solution. Flush the expanded pellet once if the supplier's EC is above your plug limit. The EC and pH limits for seedlings, and feeding, are covered in the coco peat for seed germination guide.
2. Sow or stick
For seed, drop one or two seeds into the dibble and pinch the top closed to the right depth. For cuttings, insert the stem into the pre-formed hole and firm the coir against it. Cover with a dome or film until emergence and bottom-water to keep the pellets evenly moist.
3. Grow on and feed
Remove the cover once cotyledons open. Uncharged pellets need a dilute feed from the first true leaves; with charged pellets, follow the supplier's figure for how long the charge lasts. Keep pellets damp, not saturated.
4. Transplant
Transplant when white roots show at the sides of the plug and before they wrap around it. The pellet goes into the pot or field whole, so there is no pricking out. Do not strip the net off; tearing it damages the roots that have grown through it.
Coir plugs vs peat pellets vs rockwool vs foam
| Property | Coir pellet or disc | Peat pellet | Rockwool cube | Phenolic foam plug |
|---|---|---|---|---|
| Water held at container capacity in propagation cells | Coir dust holds 750–1,100 % of its dry weight; water-filled pore space 73–80 % by volume in loose dust (Evans et al., 1996). No pellet-specific figure found. | 65 % by volume (Yafuso et al., 2019) | 87 % by volume (Yafuso et al., 2019) | 91–93 % by volume (Yafuso et al., 2019) |
| Air at container capacity | 9.5–12.6 % in loose coir dust (Evans et al., 1996); pellet figure not published | 11 % (Yafuso et al., 2019) | 5 % (Yafuso et al., 2019) | 5–7 % (Yafuso et al., 2019) |
| pH as supplied | 5.7 ±0.5 for Jiffy-7C; 5.6–6.9 across coir dust sources (Jiffy; Evans et al.) | 5.3–5.5 for standard Jiffy-7; a 4.5 version exists (Jiffy) | Naturally high; conditioned by soaking in nutrient solution at pH 5.5 (Wikipedia, Mineral wool) | Not stated in the sources read |
| EC as supplied | 0.9 ±0.4 mS/cm with fertiliser charge (Jiffy-7C); raw coir 0.3–2.9 mS/cm (Evans et al.) | 0.4–1.2 mS/cm depending on charge (Jiffy) | Inert; EC is whatever you soak it in (Grodan FAQ) | Inert |
| Water buffering between irrigations | Rewets readily; does not become water-repellent when dry (University of Kentucky CCD-TA-02 lists peat as "hydrophobic when dry", not coir) | Good retention, "hydrophobic when dry" (University of Kentucky) | Low; held water drops sharply with small tension, "may require more frequent irrigation" (Yafuso et al.) | Low, as rockwool (Yafuso et al.) |
| Biodegradable | Coir yes; net depends on material (PLA nets certified to EN13432, synthetic nets no) | Peat yes; same net caveat | No, "not biodegradable", "proper disposal" needed (University of Kentucky) | No; synthetic polymer |
| Cost and logistics | Shipped dry and compressed; stores up to two years, about a quarter of the inventory space of filled trays (Jiffy) | Same as coir | Shipped wet-ready, bulky; "high costs" and skin irritation noted (University of Kentucky) | Shipped bulky; price not sourced |
Two points stand out. The peat-versus-coir difference is small: Jiffy's sheet puts its peat and coir pellets within a few tenths of a pH unit at similar EC. Coir pellets are lighter, rewet more reliably and need no lime; peat pellets are more acidic, which suits crops that want a low starting pH.
The inert media are the outliers. Yafuso and colleagues measured 87 % water and 5 % air in rockwool plugs and 91–93 % water in foam, against 65 % and 11 % in peat, and note that high moisture and low air in short cells delays rooting and raises disease risk, while the low water buffering of rockwool and foam means they dry abruptly once irrigation stops. Coir, like peat, gives up water gradually and keeps a few more percent of air. The same paper cites modelling (Caron and Nkongolo, 1999) in which air-filled porosity fell from 19 % in a 15 cm pot to under 1 % in a 1.3 cm plug cell, so cell height matters as much as the medium. The full-crop comparison is in coco coir vs rockwool.
Problems to watch
Nets that do not break down. Jiffy's older pellets used PE and PP nets; it has since moved all its pellets to PLA netting, a plant-based polymer of 12 g/m² certified compostable to EN13432 under controlled industrial conditions. That does not mean the net disappears in a nursery bed; PLA needs the heat of a commercial composting process. Many other netted pellets still use synthetic mesh, and Botanicare's instruction for its plugs is blunt: "Only coir is compostable – remove cover before composting." Get the net material in writing before you sell pellets as plastic-free.
Binders. Bonded plugs hold together without a net because the coir sits in a binder. None of the product sheets read for this article named the binder. If your buyers want a fully natural plug, ask for the binder chemistry, or specify a netted or bare disc.
Salts. A compressed disc concentrates whatever salts the pith carried, with no perlite or peat to dilute them. Buy washed, low-EC material, put the EC limit and test method on the purchase order, and test incoming lots. When buffering is worth paying for is covered in the article on buffered vs unbuffered coco peat.
Algae and fungus gnats. Pellet tops are wet, lit and often fertilised, which is what algae needs, and the wet medium is where fungus gnats and shore flies breed. Once seedlings are up, let surfaces dry between waterings, avoid standing water in trays, and do not hold pellets wet for weeks.
Mould in storage. A seller of bonded plugs notes that "a slight formation of mould may occur" after storage and recommends keeping stock cool, preferably under 10 °C. Keep cartons dry and off the floor.
Shrinkage. The University of Kentucky sheet lists "decomposition causing substrate shrinkage" among coir's cons. In a plug used for a few weeks this is not a concern; in a bare disc filling a pot for a long crop, expect some settling.
What to specify when ordering custom discs or briquettes
A plain coir disc is a simple product, which is why the specification has to carry the detail. For bulk or private-label orders, put these on the enquiry:
- Dry diameter and thickness, plus the tray or pot size the disc must fill.
- Dry weight per disc, with tolerance. Weight determines expanded volume.
- Expanded height or volume, as a test result on the actual disc, not a generic "expands 5–7 times".
- Coir grade. Pith only or pith with short fibre; particle size range; sieved of dust or not.
- EC and pH, with the extraction method (1:1.5, 1:5 or saturated extract read very differently), reported per production lot.
- Washed, buffered, or neither. Washing rinses out loose salts; buffering also displaces potassium and sodium with calcium. The price differs.
- Binder-free and net-free, or the net material named (PLA, PP, PE) with any compostability certificate required.
- Starter charge, or "no added fertiliser".
- Moisture content at packing, low enough that discs do not mould in transit.
- Packing: shrink-wrapped stacks, cartons of a stated count, or bulk.
CVM Fiber and Industries produces washed coco peat with no calcium nitrate or other chemical treatment, so it is unbuffered, and presses it into 5 kg blocks and 650 g briquettes. Disc formats, blends and particle grades can be discussed as a custom product. For how nurseries use these formats in trays and pots, see coir for nurseries.
FAQ
What is the difference between a coir disc, a coir coin and a coir pellet?
They are the same compressed coir pith in slightly different packages. "Disc" and "coin" usually mean a bare compressed puck with no net, dropped into a pot or cell and hydrated there. "Pellet" usually means a netted product such as the Jiffy-7C, where a mesh sleeve keeps the expanded cylinder in one piece so it can be handled and transplanted whole. "Plug" is used for both netted pellets and binder-bonded products.
How much do coco coir discs expand?
Mostly upward. A netted 40 mm pellet ends up about 40 mm across and 40–45 mm tall, and Jiffy's full range runs from 20 to 75 mm in diameter and 35 to 190 mm in height. Exporters of bare discs quote expansion of five to seven times by volume. Treat seller figures as claims and ask for a measured expanded height on the specific disc you are buying.
How long does a coir disc take to hydrate?
A few minutes with warm water for a small netted pellet; larger pot-filler discs take longer. The disc is ready when it has reached full height and the top is soft enough to dibble. Drain off any standing water before sowing. For large runs, pellet expanders wet and tray hundreds of pellets a minute.
Are coir pellets better than peat pellets for seed starting?
The two are close. Manufacturer data puts coir pellets slightly higher in pH (around 5.7 against 5.3–5.5 for peat) with similar EC, and coir pellets are lighter and rewet more reliably after drying out. Peat pellets suit crops that want a low starting pH. Germination rates are generally similar; the difference that matters is salt content in the coir, so buy washed, low-EC pellets.
Do I remove the net before transplanting a coir pellet?
No. Pull the net off and you tear the roots that have grown through it. Transplant the pellet whole once roots are visible at the sides. If the net is PLA it will break down in industrial composting; if it is polypropylene or polyethylene it will not break down in the ground, so choose the net material with that in mind.
Do coir pellets contain fertiliser?
Some do and some do not. Jiffy's coir pellets carry a starter charge; bonded plugs such as Eazy Plug are sold with a charge said to last two to three weeks; plain exporter discs normally carry none. Check the sheet, and if there is no charge, start a dilute feed from the first true leaves or hydrate with a weak seedling solution.
Why do coir pellets get a green film on top?
Algae. The pellet top is wet, exposed to light and often fertilised, which is all algae needs. It is a sign the surface is staying too wet. Once seedlings are up, let the pellet tops dry slightly between waterings, avoid standing water in the tray, and move trays through the propagation area rather than holding them for weeks.
Can coir discs be made to my own size?
Yes, within the limits of the press tooling. Specify dry diameter and thickness, dry weight with tolerance, expanded height, coir grade, EC and pH with the test method, washed or buffered, net or binder requirements, and starter charge. The more of these are on the purchase order, the more consistent the lots will be.
Ask about disc formats, briquettes or custom coir grades through the contact page.
Sources
- Jiffy Products International: Jiffy Pellets brochure, propagation solutions (technical data for Jiffy-7, Jiffy-7C and QSM pellets)
- Jiffy Group: Jiffy Celebrates the 60th Anniversary of Jiffy-7 Pellets (company article on pellet history and PLA netting)
- Garden City Plastics: Jiffy-7C 50 mm Coir Pellet with 20 × 40 mm hole, product listing
- Yafuso, E. J., Fisher, P. R., Bohorquez, A. C. and Altland, J. E.: Water and Air Relations in Propagation Substrates, HortScience 54(11), 2024–2030 (2019)
- Sparks, B.: How Air and Water Affect Propagation Substrates in Unrooted Plant Cuttings, Greenhouse Grower (2020)
- Evans, M. R., Konduru, S. and Stamps, R. H.: Source Variation in Physical and Chemical Properties of Coconut Coir Dust, HortScience 31(6) (1996)
- Byrd, C., Sharma, A. and Ying, Q.: Selecting Growing Media for Soilless Systems, CCD-TA-02, University of Kentucky Center for Crop Diversification (2025)
- Root!t (Hydrogarden): Free Propagation Guide (undated)
- Botanicare: CocoPro Propagation Plugs, product page
- FloraFlex Incubator Coco Plug, retailer listing (Hydrotek Hydroponics)
- Eazy Plug CT77 and related plugs, wholesaler and retailer listings (Eddis Wholesale, Aqua Gardening)
- Indian coir exporter listing for coir discs, GlobalLinker (sizes, thickness and expansion claims)
- Miller, L.: Coconut Pellet Seed Starting – How To Use Coir Discs For Seed Planting, Gardening Know How (2022)
- Wikipedia: Mineral wool, horticultural use section (accessed 2026)
- Grodan: Frequently asked questions about stone wool (accessed 2026)