Seed Pack Paper: Breathability, Print, and Shelf Requirements

A seed pack base paper has three jobs: put the pack in the right moisture class for the seed, carry a statutory label that stays legible until the pack is opened, and survive hanging racks and handling without tearing. Breathability is not on that list, and in humid storage it is usually what goes wrong.

That runs against a common assumption. Paper seed packets are often sold as “breathable”, as if letting air through were good for seed. For a home-garden packet in a dry, cool climate it can be harmless. For a vegetable seed lot that sits through an Indian monsoon in a dealer’s godown, a pack that lets moisture through lets the seed take it up, and Indian seed certification already treats that as a different, stricter case.

This piece is for the converter, printer or laminator who makes seed packets and seed pouches, and for the technical buyer at a seed company who has to approve the structure. It covers retail vegetable and flower seed packs and small hybrid seed pouches. It is not about woven sacks for bulk field-crop seed, and it is not about plantable seed paper, the craft product with seeds embedded in the sheet. It makes no claim about germination or agronomic performance for any paper, ours included; where germination figures appear, they come from published trials of container types.

What does a seed pack actually ask of its base paper?

A seed pack asks its base paper to do three things: hold or support a moisture barrier matched to the seed’s storage limit, take and keep the label the Seeds Rules require, and stand up to filling, hanging and handling. The paper is rarely the barrier itself. It is the print surface, the stiffness and the carrier for whatever coating or laminate sets the moisture class.

The moisture class comes first because the regulator has already split it. The Indian Minimum Seed Certification Standards, 2013, published by the Central Seed Certification Board, give each crop two moisture ceilings: one for ordinary containers and a lower one “for vapour-proof containers”. Seed going into a sealed, vapour-proof pack has to be dried further before packing, so the pack’s barrier and the seed company’s drying step are one decision, not two.

The label comes second. Rules 8 and 9 of the Seeds Rules, 1968 set out what the mark or label must carry and require it to be conspicuous and legible on the innermost container. On a small retail packet the innermost container is the packet, so the paper face carries legal text.

For the terms used below, such as air permeability, Cobb and WVTR, see our coating base paper glossary for converters.

The weight of each job changes with the seed. A low-value, fast-turnover packet sold within one season can tolerate a modest barrier. An expensive hybrid that may sit in the trade for a year cannot. Specify from the seed, its value and its route, not from the packet format.

Is a breathable paper seed packet good or bad for the seed?

For storage in humid conditions, a breathable packet is bad for the seed, because it lets the seed’s moisture content follow the humidity of the air around it. Seed is hygroscopic: it gains or loses water until it reaches equilibrium with the surrounding air. A pack that passes water vapour freely gives the seed no protection from a wet season.

Tamil Nadu Agricultural University’s seed technology notes sort seed packaging into three groups. “Moisture pervious” materials, which it lists as cotton bags, paper, cardboard and fibre board, are acceptable only where the store itself controls temperature and humidity. “Moisture resistant” materials such as polyethylene, plastic films and aluminium foil slow the passage of moisture but equilibrate over time. “Moisture impervious” containers, such as 700 gauge polythene bags, hold the seed’s moisture content where it was at packing.

Equilibrium moisture content is the moisture a material settles at when it has stopped exchanging water with air at a given temperature and relative humidity. It is the number that tells you what a breathable pack will let the seed become.

The size of the effect is published for grain. The University of Arkansas extension equilibrium tables (Sadaka and Bautista, FSA-1074) give, at 80 °F (about 27 °C), long-grain rice at 12.7 per cent moisture in 60 per cent relative humidity, 15.0 per cent at 75 per cent and 18.3 per cent at 90 per cent. For soybean the same steps run 10.5, 15.1 and 26.9 per cent. Compare that with the certification ceiling for paddy seed in an ordinary container, 13.0 per cent: rice held at 75 per cent relative humidity would settle above it. These are grain figures, not certified seed lots, and we found no equivalent published table for vegetable seed. The direction of the effect is the same for any hygroscopic seed. For a converter, that means a barrier has to be specified against the wettest months on the seed’s route to market, not against an annual average humidity.

India’s air is wet enough for this to matter for most of the year. According to Jaswal and Koppar of the India Meteorological Department, writing in Mausam in 2011 from 1969 to 2007 records, the all-India annual mean relative humidity is 63.9 per cent. That is an annual average; monsoon and coastal conditions run well above it.

Where breathability is harmless is a short-life pack in a dry route, or a pack whose seller stores stock in a conditioned room. The cases where a seed company actually wants a breathable pack are fewer than packet marketing implies. Our tea stream’s work on MVTR benchmarks through an Indian monsoon shows the same arithmetic for a different dry product.

What moisture limits does Indian seed certification set by container type?

Indian seed certification sets a lower maximum moisture for seed packed in vapour-proof containers than for seed in ordinary containers, crop by crop, typically two to five percentage points lower. The difference tells the converter what a vapour-proof claim implies: the seed inside has been dried further, and the pack must keep it there.

The values below are from the “Seed Standards” tables of the Indian Minimum Seed Certification Standards, 2013. The same figures apply to foundation and certified seed.

The Indian standard does not define “vapour-proof container” in measurable terms. It is a row label, not a transmission limit. The clearest published number we found comes from the United States. Under 7 CFR 201.36c, a hermetically sealed seed container may pass no more than 0.05 g of water per 24 hours per 100 square inches of surface at 100 °F. Converted, that is about 0.78 g/m² per day at 37.8 °C, which is our arithmetic, not a figure in the rule. The same rule caps seed moisture in such containers at, for example, 5.5 per cent for tomato and 6.5 per cent for onion. That transmission figure is useful as a yardstick for what “vapour-proof” means in practice. It is not an Indian requirement, and the humidity condition behind it should be confirmed from the full rule before anyone specifies against it.

Plain paper does not come close. Uncoated paper transmits water vapour freely, which is why every structure that claims a vapour-proof class puts a film, foil or barrier coating on it. How open a given paper is depends on its pore structure, covered in our piece on porosity and air permeability in coating base paper.

How much does the container change seed storability in published trials?

In published Indian trials, seed kept in moisture-pervious containers loses germination far faster under ambient storage than seed in polythene or aluminium foil pouches. The gap is small in the first months and very large after a year, which is why the container decision matters most for seed that will sit in the trade.

The clearest dataset we found is from the University of Agricultural Sciences, Dharwad. Saisanthosh and Biradar Patil, in the Journal of Pharmacognosy and Phytochemistry in 2018, stored onion seed of cultivar Arka Kalyan for 20 months under ambient conditions in Dharwad.

The authors put it plainly: “The seeds packed in cloth bags lost their complete germinability within 18 months of storage.”

Seed scientists summarise the mechanism with Harrington’s rules of thumb, as given in TNAU’s seed storage notes: within roughly 5 to 14 per cent seed moisture, each 1 per cent fall in moisture content doubles the life of the seed, and each 5 °C fall in storage temperature does the same. The pack governs moisture; the godown governs temperature.

Three limits on reading this. The trial used cloth, not paper, and one cultivar at one location. Onion is a notoriously short-lived seed, so the curve is steeper than it would be for most crops. And germination is the seed company’s measure; it belongs on their certificate, not on a converter’s or paper supplier’s datasheet. Nothing in this table describes any particular paper.

Which paper-based seed pack structures fit which seed?

The structure depends on the seed’s moisture class and value. An uncoated paper envelope suits short-life, low-value seed in a dry route or a conditioned store. Long-life or high-value seed going through humid storage needs a vapour-proof structure, which on paper means a foil or high-barrier layer, with the paper as the print face and stiffener.

The ratings below are relative, drawn from the sources above and general converting practice. They are not measured values for any product.

Two cautions. A paper face does not change the pack’s legal category: a structure with a plastic layer is still multilayered plastic packaging for EPR purposes, which our food-contact compliance guide for coated paper in India touches on alongside the food-contact rules. And foil laminated to a stiff paper cracks more readily at a sharp crease than foil inside a film laminate, so a “vapour-proof” paper/foil pack has to be tested after folding and filling, not as flat web.

What does the seed label law mean for print on the pack?

The Seeds Rules, 1968 turn the seed pack’s print face into a legal document. Rule 8 lists what the mark or label must carry and Rule 9 requires it to be conspicuous and legible on the innermost container, so on a retail packet the paper’s print and rub performance decide whether the pack stays compliant until it is opened.

Rule 8 requires, among other things, the particulars specified under Section 6(b) of the Seeds Act, 1966, the net content by weight in metric units, the date of test, and the seller’s name and address. For treated seed it adds a statement that the seed is treated, the chemical name of the substance and a caution such as “Do not use for food, feed or oil purposes”; for mercurials and similarly toxic substances the caution is the word “POISON”, shown prominently in red. Rule 7 makes the person named on the label responsible for its accuracy while the seed is in the unopened original container.

Two consequences for the substrate follow:

1. Variable data. The date of test and lot details change with every lot, so they are usually added late, by inkjet, thermal transfer or stamp, on top of a pre-printed packet. Uncoated and lightly sized paper takes these well. A closed, glossy barrier face may need a print-receptive coating or a primer.
2. Durability. Packets rub against each other in cartons and on racks for months. Abrasion resistance of the print can be tested with a Sutherland rub tester under ASTM D5264. Test the variable-data area as well as the pre-printed design, because that is the text the law cares about.

Treated seed raises a third point. Fungicide or insecticide dressing can dust onto the inside face. A pack for treated seed needs an inner face that holds that dust and does not let it show through or rub through to the print. We found no published test specific to this; it has to be checked with the actual dressing.

For general ink adhesion and registration on paper, the Wrap & Carry converters’ guide to paper printing and substrate preparation covers the press side.

What does the shelf ask of the seed pack substrate?

On the shelf, a seed pack has to hang or stand without tearing at the hang hole or the top seal, keep its print readable, and survive repeated handling by dealers and buyers. Those are tear, stiffness and seal-strength properties, and they belong on the specification alongside the barrier.

Retail vegetable seed packets typically reach the farmer through agri-input dealers, where they hang on strips or sit in cartons and get picked up and put back many times. The failure modes are mechanical. A packet tears from the punched hang hole. A top seal opens under the weight of a heavier seed. A crease through a foil layer opens a path for moisture before the packet is even sold.

The tests are standard. Tear resistance by the Elmendorf method is ISO 1974. Seal strength on the finished pack is ASTM F88. Bending stiffness, which controls whether a hanging packet holds its shape, is TAPPI T 489 or ISO 2493-1. We found no published target values for seed packets; they come from the seed company’s own handling trials.

Moisture in the paper itself also matters on the shelf. A paper face that takes up humidity will curl a laminated pack and can soften a glued seam. Specify moisture content and its variation across the reel on the certificate, not just an average.

Shelf performance also depends on the dealer’s conditions as much as on the pack. A pack hung in direct sun on a shop front faces temperature cycling that no datasheet describes.

What belongs on a seed pack base paper specification?

A seed pack base paper specification needs two lists: properties of the paper, which the paper supplier controls, and performance of the finished pack, which the converter answers for. For seed, the barrier test conditions and the variable-data print area need their own lines, because generic paper certificates leave both out.

For the base paper, specify at minimum:

1. Grammage to ISO 536 or TAPPI T 410, with a tolerance, and thickness to TAPPI T 411.
2. Moisture content to TAPPI T 412, with a limit on cross-reel variation as well as the average.
3. Air permeance by the Gurley method to ISO 5636-5, which indicates how open the sheet is and how much coating it will absorb.
4. Water absorptiveness (Cobb) to ISO 535, for glued seams and water-based print.
5. Tear resistance to ISO 1974 and tensile strength to ISO 1924-2, both directions.
6. Bending stiffness to TAPPI T 489 or ISO 2493-1.
7. Surface suitability for the variable-data method in use: inkjet, thermal transfer or stamp.
8. Reel details: width and tolerance, core diameter, joins per reel and how joins are marked.

For the finished pack, agree with the seed company:

1. WVTR at the right condition. TAPPI T 448 tests paper and board at 23 °C and 50 per cent relative humidity; TAPPI T 464 tests at 37.8 °C and 90 per cent. For Indian storage, T 464 or an equivalent tropical test is the relevant one, and the two results should never be compared with each other.
2. WVTR on creased and filled packs, not only flat web.
3. Seal strength to ASTM F88 and rub resistance of the variable-data area to ASTM D5264.
4. The seed moisture at packing, from the seed company, matched to the container class it is labelled for.

A specification will not tell you how a web runs on a particular packet-making or pouch line. Only a reel trial on the actual machine, long enough to see reel-to-reel variation, can tell you that. The same discipline applies to a release liner base paper specification, where surface consistency decides coating uniformity, and to the sachet paper requirements that share the same form-fill-seal machines.

Where a coating base paper fits in a seed pack

A coating base paper is not a seed pack material on its own. It arrives uncoated, with no moisture barrier and no heat-seal layer, so it is moisture pervious and cannot hold seed in the vapour-proof class. A seed company that wants a ready-to-print packet stock, or a converter who wants a finished laminate, should buy that, not a base. And for high-value hybrid seed with a long trade life, a structure with an intact foil or high-barrier film is still the dependable choice; paper changes the outside of that pack more than the protection inside it.

A base fits the converter or coater who builds the structure. If your business coats, extrudes or laminates onto paper, the base decides how much coating it absorbs, how evenly, how it takes print and late-stage coding, and how it behaves at the creases of a finished packet. Those properties are fixed at the paper machine, before the reel reaches your line.

Pakka is developing flexC base, a coating base paper in the 40-60 GSM band, bleached and unbleached, intended as a substrate for barrier chemistries including silicone, biopolymer and plastic coatings. Seed packs are one of the eight applications named for it, alongside confectionery wraps, snack pouches, sachets, medical packaging, release liners, dry food liners and tea pouches. These details are disclosed in Pakka Limited’s Investor Presentation for Q1 FY2026-27, filed on 18 August 2026 (BSE 516030 / NSE PAKKA). It is a development programme, not a stocked product, and it has no published performance data. No barrier, tear, print or germination figure should be attributed to it by anyone, including us.

The two names are easy to confuse, so to be clear: flexC base is the coating base paper described above, sold to coaters and converters. flexC is a separate product, a finished compostable flexible-packaging laminate that Pakka already supplies to brand owners, with its own published specifications. A converter looking for a base to coat or laminate wants the first; a brand looking for a finished laminate wants the second.

If you build seed pack structures, ask any base supplier, us included, for reels you can coat or laminate with your own materials, print with your own variable-data system, and test as filled, creased packs with your customer’s seed. A datasheet will not tell you how that goes.

Frequently asked questions

What paper is used for seed packets?

Simple retail seed packets are usually glued envelopes of uncoated or lightly coated paper, which print well but let moisture through. Longer-life and hybrid seed packs use paper laminated to aluminium foil and polyethylene, or a full film laminate, so that the pack holds the seed at its packing moisture. The paper gives the print face and stiffness; the foil or film gives the moisture barrier.

Is a breathable seed packet better for seeds?

Not in humid storage. A breathable packet lets the seed’s moisture content follow the air, and seed stores longer when it is kept dry. Tamil Nadu Agricultural University’s seed notes treat paper as moisture pervious and acceptable only where the store controls temperature and humidity. Indian certification sets lower moisture limits for vapour-proof containers.

What moisture should seed be packed at in a vapour-proof pouch in India?

The Indian Minimum Seed Certification Standards, 2013 set crop-specific limits for vapour-proof containers, for example 8.0 per cent for paddy and wheat and 6.0 per cent for tomato, chillies, brinjal and onion. Ordinary containers carry higher limits. The seed company dries to the limit; the pack has to keep the seed there.

What must be printed on a seed packet in India?

Rule 8 of the Seeds Rules, 1968 requires the particulars under Section 6(b) of the Seeds Act, 1966, the net content by weight, the date of test, the seller’s name and address, and, for treated seed, the treatment, the chemical name and a caution. Rule 9 requires the label to be conspicuous and legible on the innermost container.

Is seed paper the same as seed packet paper?

No. Seed paper, sometimes called plantable paper, is a craft paper with seeds embedded in the sheet, meant to be planted whole. Seed packet paper is a packaging grade that holds loose seed, carries the statutory label and, in better packs, supports a moisture barrier.

Last reviewed: October 2026.

Building seed pack structures on a paper base? Pakka’s flexC base programme covers the 40-60 GSM band in bleached and unbleached, for coaters and converters who coat, extrude or laminate their own webs. If you would like to discuss a trial, send us a flexC base trial enquiry with the pack format, the barrier and sealant you apply, the seed types you pack and your reel width. Technical brochures for our paper and packaging range are on the resources page, and general enquiries reach us through the same contact page.

Sources

• Central Seed Certification Board, Indian Minimum Seed Certification Standards, 2013 (state government copy)
• The Seeds Rules, 1968, Rules 7, 8 and 9 (NSAI copy)
• US Code of Federal Regulations, 7 CFR 201.36c, Hermetically-sealed containers
• Tamil Nadu Agricultural University, Seed storage: packing materials and storage factors
• Sadaka and Bautista, Grain Drying Tools: Equilibrium Moisture Content Tables and Psychrometric Charts, University of Arkansas FSA-1074
• Jaswal and Koppar, Recent climatology and trends in surface humidity over India for 1969-2007, Mausam 62(2), 2011
• Saisanthosh and Biradar Patil, Effect of packaging materials and moisture content on seed storability of onion, Journal of Pharmacognosy and Phytochemistry 7(4), 2018
• TAPPI T 448 and T 464 (WVTR of paper); ISO 5636-5 (Gurley air permeance); ISO 1974 (Elmendorf tear); ASTM D5264 (Sutherland rub); ASTM F88 (seal strength); TAPPI T 410, T 411, T 412, T 489; ISO 535, ISO 536, ISO 1924-2, ISO 2493-1
• Pakka Limited, Investor Presentation Q1 FY2026-27, filed 18 August 2026 (BSE 516030 / NSE PAKKA)

Browse all Pakka articles.