Catalog buyer guide · Seed varieties
Vegetable seed lot certificates: germination, purity and ISTA explained
Sources reviewed: · SeedMatch Group editorial team
Short answer
Ask for test results that represent the whole seed lot: an ISTA Orange International Seed Lot Certificate covers sampling and testing by an accredited laboratory, while a Blue certificate covers only the submitted sample. ISTA sets no minimum germination or purity, so the buyer states the thresholds; varietal identity and plant health need separate documents.
Three questions a seed document must answer
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A seed purchase carries three separate risks, and no single paper answers all of them. Keeping them apart avoids the most common gap in seed tenders.
| Question | Typical evidence | Who issues it |
|---|---|---|
| Is this lot of good analytical quality (germination, purity, other seeds, moisture)? | ISTA Orange International Seed Lot Certificate, or a laboratory report for the lot | An ISTA-accredited laboratory |
| Is it the variety stated on the label? | Variety denomination and, where used, official varietal certification (national scheme or OECD Seed Schemes) | National seed certification authority |
| Is it free of regulated pests for the destination? | Phytosanitary certificate with any additional declarations or tests the importing country requires | Plant protection organisation of the exporting country |
Sources: [3] International Seed Testing Association (ISTA), [4] OECD, [6] International Plant Protection Convention (IPPC), FAO
ISTA Orange versus Blue certificates
The Orange International Seed Lot Certificate represents the seed lot as a whole. The accredited laboratory is responsible for both sampling and testing, so lot preparation, lot size, lot identification and sampling follow strict ISTA rules.
The Blue International Seed Sample Certificate represents only the sample that was tested. The sample is provided by the customer, so the certificate does not officially represent the entire seed lot. For a commercial purchase, buyers usually ask for the Orange certificate when it is available for the species and test.
Sources: [1] Oregon State University Seed Laboratory (ISTA-accredited), [2] International Seed Testing Association (ISTA)
What the certificate reports
An Orange certificate identifies the testing laboratory, the species by scientific name and the seed lot, and reports the results of the tests requested. Common test fields include:
- Purity: the proportion of pure seed, other seeds and inert matter.
- Other seed determination: seeds of other species found in a larger working sample.
- Germination: the percentage of normal seedlings under ISTA test conditions.
- Moisture content, and further tests such as tetrazolium viability or thousand-seed weight where requested.
Sources: [2] International Seed Testing Association (ISTA), [1] Oregon State University Seed Laboratory (ISTA-accredited)
ISTA does not set minimum germination: you do
ISTA has no seed quality standards for minimum purity or germination; it ensures that tests are reliable and performed to its rules. The levels required depend on the buyer and on any certification programme or national marketing rule that applies.
Certificates are valid only for the seed as tested. Treating seed after testing invalidates the certificate, because it no longer represents the seed. If you are buying treated or coated seed, ask when the test was done relative to treatment and whether the laboratory tested the treated seed.
Sources: [1] Oregon State University Seed Laboratory (ISTA-accredited)
The fields a seed specification should add
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Variety and denomination
Exact variety denomination, or the traits an accepted equivalent must match. UPOV explains how variety denominations identify a protected variety.
Lot thresholds
Your minimum germination and purity, maximum moisture where storage or transit is long, and the latest acceptable test date.
Certification
Whether certified seed is required (national scheme or OECD varietal certification) and which category.
Treatment and pack
Untreated, treated (active substances stated and permitted in the destination), pelleted or primed; pack size in seed count or weight.
Plant health
The destination's import permit, phytosanitary certificate and any additional declarations or pathogen tests required for the species.
Sources: [5] UPOV, [4] OECD, [6] International Plant Protection Convention (IPPC), FAO
From specification to request
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The catalog seed-varieties page includes a request form for crop, variety, quantity, treatment and documents. State your thresholds there, and the team checks the supplier's certificates against them before any offer is presented. SeedMatch does not publish seed prices or claim germination results for any lot.
Frequently asked questions
What is the difference between an ISTA Orange and Blue certificate?
An Orange certificate represents the whole seed lot because the accredited laboratory both samples and tests it. A Blue certificate represents only the sample the customer submitted, not the lot.
Does ISTA set a minimum germination rate?
No. ISTA standardises how tests are done and reported. Minimum germination and purity come from the buyer's specification, certification programmes or national marketing rules.
Is a seed certificate still valid after treatment?
No. A certificate is valid only for the seed as it was tested; treating the seed afterwards invalidates it because the certificate no longer represents that seed.
Does a germination certificate prove the variety?
No. Germination and purity tests describe analytical quality. Varietal identity is covered by the variety denomination and, where used, official varietal certification such as the OECD Seed Schemes.
Which document covers plant health?
The phytosanitary certificate issued by the exporting country's plant protection organisation, with any additional declarations or tests the importing country requires for that species.
Ready to request a seed lot?
Use the seed request in the catalog to send crop, variety, quantity, treatment and the certificates you require. A specialist reviews each request and the supplier documents before any offer is presented. Commercial projects start at USD 250,000.
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Each participant remains responsible under applicable law for the requirements of its own role. Seed suppliers are responsible for the seed and documents they supply; buyers and importers for import permits, local registration and due diligence. This article is not legal or regulatory advice.
Availability and the ability to trade depend on the law of each origin, destination and transit country and on the relevant permits and approvals. SeedMatch Group is not a manufacturer, importer, exporter, seller or regulatory approver; requests are reviewed by our team before any commercial introduction. Each participant is responsible for the requirements of its own role under applicable law: suppliers for their products in the origin and destination countries, buyers for their own import permissions and due diligence. We do not guarantee any supplier's compliance. Participant responsibilities · Regulation & restricted items
Related catalog pages and guides
References
Official standards, accredited-laboratory guidance and international schemes cited in this guide. Points marked “SeedMatch analysis” are our interpretation.
- ISTA FAQ: Orange and Blue certificates, quality standards and certificate validity — Oregon State University Seed Laboratory (ISTA-accredited) · 2025-01-06
- ISTA Learning Base — Orange International Seed Lot Certificate: required content — International Seed Testing Association (ISTA) · accessed 2026-10-27
- International Rules for Seed Testing — International Seed Testing Association (ISTA) · accessed 2026-10-27
- OECD Seed Schemes — varietal certification of seed moving in international trade — OECD · accessed 2026-10-27
- Explanatory notes on variety denominations — UPOV · accessed 2026-10-27
- ISPM 12: Phytosanitary certificates — International Plant Protection Convention (IPPC), FAO · accessed 2026-10-27