Good Agricultural and Collection Practice (GACP) is the quality system for plants that will become the raw material for medicines. Its main text is guideline EMA/HMPC/246816/2005 Rev. 1 from the European Medicines Agency (EMA), adopted in July 2025. Its central demand is that every batch can be traced to its source.
Part 1 covered records, staff, the farm site, planting material, crop records, pest control, and harvest and drying. This part covers what happens after drying: storage, laboratory testing, release, audits, the Thai rules, where to start, and why first audits fail.
This is Part 2. Part 1: Good Agricultural and Collection Practice for Cannabis: Records, Farm Site, Crop and Drying (Part 1 of 2)
10. Storage and Transport
Packed dried material “should be stored in a dry, well-aerated building”. Aerated containers are advised “to reduce the risk of mould formation or fermentation”. Reusable packaging must be cleaned and dried before each use.
The label “must be clear, permanently fixed and made from non-toxic material”. It shows the material name, lot code, quantity, date and status.
The store keeps three groups apart:
- quarantined material, which is waiting for test results;
- released material, which has passed and may be shipped;
- rejected material, which has failed.
Pest control continues inside the store and on the vehicles. Many operators also keep retention samples, a small portion of each lot kept back in case it needs testing later. This is common industry practice.
Translator’s note: In Thailand, outdoor air is often humid. Ventilating a store with that air carries moisture in rather than out. A “dry” store here usually needs air conditioning or a dehumidifier, plus a temperature and humidity logger. Lorries left in the sun get very hot, so plan short, shaded or air-conditioned transport and record the conditions.
What to do: Mark three separate areas with signs: quarantine, released and rejected. Then no lot can be shipped by mistake before its test result arrives.
11. Testing and Release
The sampling plan
A sampling plan defines four things. It defines the lot. It defines the increments, which are the small portions taken from different parts of the lot. It says where those portions are taken and who takes them. A sample taken only from the top of a bag tells you only about the top of the bag.
What must be tested
A certificate of analysis reports the tests run on a sample (how to read a certificate of analysis). Contaminant tests usually cover heavy metals, pesticide residues, disease-causing microorganisms and mycotoxins (toxins left behind by moulds). Check with DTAM which tests Thai rules currently require for flower that is sold or exported. The US state of California requires a broader panel of eight categories.
| Test | Purpose | Where required |
|---|---|---|
| Cannabinoids and terpenes | Identity and strength | California panel |
| Moisture content and water activity | Shows whether dried flower can resist microbes | California panel |
| Microbial impurities | Disease-causing organisms and total counts | California panel |
| Mycotoxins | Toxins that remain after mould has grown | California panel |
| Heavy metals | Uptake from soil, water and inputs | California panel |
| Pesticide residues | Residues from crop protection | California panel |
| Residual solvents | Solvent left in processed products | California panel |
| Foreign material | Physical contamination | California panel |
Translator’s note: California is useful here as an example of a full test panel. For a Thai grower, confirm the domestic minimum with DTAM. An export buyer may ask for more tests. Ask the buyer for their test list and limits before you plant, because the list decides your inputs and your drying target. For laboratories, look for accreditation to ISO/IEC 17025 for each test you need. Ask each laboratory for its accreditation certificate and check that its scope lists that test.
Limits differ between markets
Numerical limits vary a great deal, so read them from the rules of the market you sell to. The 2023 review by Gwinn and colleagues in Frontiers in Microbiology shows how wide the gap is.
Across US jurisdictions, action limits for total yeast and mould range from 100 to 100,000 colony-forming units per gram (CFU/g). CFU/g is the number of live microbe colonies that grow from one gram of sample. For dangerous species such as Aspergillus and Fusarium, the authors propose a limit of 10 CFU/g.
California requires laboratories accredited to ISO/IEC 17025, the international standard for testing-laboratory competence. It also forbids changing a certificate of analysis after it is issued without the regulator’s permission.
Out-of-specification results and recalls
An out-of-specification result is a test result outside the agreed limit. Treat it as an event to investigate. Do not keep retesting until a passing number appears. Work through these steps:
- Quarantine the lot.
- Check whether the result came from a laboratory error.
- Extend the check to other lots that shared the same input or the same period.
- Decide whether to reprocess, reject or destroy the lot.
- Record the decision, the reasons and a signature.
A recall runs the same process in reverse, and it depends on traceability. Your procedure states who declares the recall and who is notified. It also explains how you compare the quantity shipped with the quantity recovered.
Testing after drying cannot rescue mouldy material. The Gwinn review notes there are “no proven technologies to degrade or detoxify” mycotoxins once they have formed.
What to do: Write a one-page out-of-specification procedure with the five steps above, and name the person who signs. When a bad result arrives, nobody can then quietly retest it or ship the lot.
The European Pharmacopoeia monograph
The European Pharmacopoeia is Europe’s official book of quality standards for medicines. A monograph is its legally referenced specification for one material. It fixes which tests must be run and what the limits are, so two laboratories testing the same batch reach the same verdict.
Since 1 July 2024, the European Pharmacopoeia has included a monograph for Cannabis flower (monograph 3028, Supplement 11.5). It defines three chemotypes (chemotypes explained).
| Chemotype | Specification (dry-weight basis) |
|---|---|
| THC-dominant | At least 5.0% total THC, at most 1.0% total CBD |
| Intermediate | At least 1.0% each of total THC and total CBD, THC:CBD ratio between 0.2 and 5.0 |
| CBD-dominant | At least 5.0% total CBD, at most 1.0% total THC |
The main test groups are:
- Identity: inspection by eye and under the microscope, plus an HPTLC fingerprint. HPTLC (high-performance thin-layer chromatography) is a lab method that produces a characteristic pattern of a plant’s compounds.
- Assay (content): total THC and total CBD, counting the acid and neutral forms together. For flower dispensed to patients, content must stay within ±10% of the declared value.
- Foreign matter: for flower prescribed as a medicine, no seeds and no leaves longer than 1.0 cm.
- Loss on drying: measured at 40 °C under vacuum for 24 hours. The limit reported in the published version is 12%.
- Aflatoxin B1: the general herbal-drug limit of 2 µg/kg (micrograms per kilogram) applies.
- Heavy metals: for a medicinal product, the ICH Q3D limits based on inhalation exposure. ICH Q3D is the international guideline on metal and other elemental impurities in medicines.
- Pesticides and microbial quality: set by the general herbal-drug and microbiology chapters for the intended use and route. The monograph itself does not list figures for these.
Translator’s note: If you aim to supply the European medical market, this monograph is the yardstick your flower will be measured against. Ask your buyer whether it applies to your material. Then compare a trial lot’s lab results with the table above, so you see the gaps before you commit a full crop.
Judging a “pharmaceutical-grade” claim
On its own, “pharmaceutical-grade” has no fixed legal meaning. These questions give it a concrete meaning:
| Ask | A solid answer | A weak answer |
|---|---|---|
| Which certificate, issued by whom, valid until when? | A named regulator or accredited certifier, a scope and an expiry date | “We follow GMP standards” |
| Which steps does that certificate cover? | Cultivation, drying, testing, packing and release, listed separately | “The whole process” |
| Can I see the certificate of analysis for this lot? | A report for this specific lot from an independent laboratory | An old one-off report or a marketing summary |
| Against which specification were the results judged? | A named monograph or a regulator-approved specification | Numbers with no limits beside them |
| How consistent is the content across recent lots? | Actual figures from several lots | “Very consistent” |
A result counts as a pass only against a stated limit.
In the European supply chain, drying is usually expected to happen inside the GMP-certified operation. GMP (Good Manufacturing Practice) is the standard for making medicines (EU-GMP explained). So a farm with GACP certification alone usually supplies an intermediate material to a GMP manufacturer. It does not usually sell finished flower to a pharmacy.
What to do: Use the table above whenever you buy genetics, inputs or services that claim to be “pharmaceutical-grade”. Ask your future buyer the same questions early. Their answers tell you whether you should dry and pack the crop yourself or ship it to a GMP site.
12. Self-Inspection, Audits and Certification
Self-inspection is an audit you run on your own farm on a fixed schedule. Each finding gets an owner and a deadline, and its closure is documented.
An auditor does little farming during a visit. The usual method is to pick one finished lot and trace it backwards, one step at a time:
- Which growing block did it come from?
- Which propagation batch, and which mother plant?
- Which spray records apply to it?
- Which operators handled it, and where are their training records?
- Whose signature released it?
In Thailand, the certifying body is the Department of Thai Traditional and Alternative Medicine (กรมการแพทย์แผนไทยและการแพทย์ทางเลือก). According to law-firm summaries, its inspectors review soil, water, pesticide use, worker hygiene and postharvest handling. Ask DTAM for the current validity period of the certificate and the schedule of follow-up inspections.
What to do: Once a month, pick one finished lot and trace it yourself through the five questions above. Note each step where the trail breaks. This is the same test the auditor will run, so you find the breaks first.
13. The Thai Context
Thailand legalised medical cannabis in 2018, the first country in Asia to do so. In June 2022, cannabis flower was removed from the narcotics list.
Then came the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568, issued under the Thai Traditional Medicine Protection Act B.E. 2542. It was signed on 23 June 2025, published in the Royal Gazette on 25 June 2025, and came into force on 26 June 2025. It classifies cannabis flower (ช่อดอกกัญชา) as a controlled herb (how Thai rules changed 2022–2026). Flower may be sold only against a PT 33 (ภ.ท.33) prescription covering at most 30 days (PT 33 explained). Advertising and online sale of flower are prohibited.
Under this framework, flower that is sold or exported must come from a cultivation site certified by the Department of Thai Traditional and Alternative Medicine for good agricultural and collection practice. Every export requires a detailed report to the licensing authority.
Translator’s note: The rules tightened again in 2026. The Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569, in force since 30 April 2026, tightens licence criteria for cannabis flower (the 2569 regulations explained). The Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569, in force since 26 April 2026, restricts licences for extracts above 0.2% THC. The draft Cannabis Control Act is not law yet: the Cabinet approved the draft on 22 September 2026 and sent it to the House (where the draft act stands). Check your licence against the current rules before each new season.
Keeping records for a foreign regulator as well as the Thai one
The Thai inspector checks the national scheme. A foreign buyer, and the regulator behind that buyer, checks their own rules. The European guideline itself points abroad, because irrigation water must meet the destination country’s standards.
So write your specifications, water testing, restricted product list and release test panel against the strictest market you plan to serve (the export pathway explained). Then one set of records can satisfy both sides.
Where a farm in this region should start
- Read the source documents yourself. Read the World Health Organization (WHO) GACP guidelines and the national rules that actually bind you. Then you will know the real requirements, not someone’s summary of them.
- Find your customer first. The receiving manufacturer’s specification decides which tests you run and which limits you must meet.
- Start the records before construction. Records cannot be created afterwards. A batch either has records written at the time, or it has none.
- Solve drying first. In this climate, drying decides the facility budget (see Part 1, section 9).
- Budget for a quality function. That means a dedicated person, not a spare-time task, plus testing of every batch and regular audits.
The region also has real advantages. Sunlight is strong and steady all year. Inputs such as coco coir and rice husk are produced locally. The agricultural export sector already works with GAP schemes, traceability and export paperwork for other crops.
What to do: Before you spend on buildings, get your target buyer’s specification in writing and read it next to the WHO guidelines and the Thai rules. List every requirement you do not yet meet. That list becomes your project plan.
14. Realistic Workload and Why First Audits Fail
For a small farm, the change is less about equipment and more about time and habits. The physical work is modest:
- sealing and screening the drying and packing rooms;
- a lockable store for inputs, with separate zones;
- fixing the drainage;
- calibrated sensors and scales.
The real load is the recurring work. You write procedures and train staff on them. You fill in logs on the same day. You follow up on lab results, run self-inspections, and keep the archive easy to search for years. Testing costs grow with the number of strains and lots, not with the number of hectares.
The patterns below come from commonly reported field experience. They are not taken from an official regulatory list.
| Failure pattern | What the auditor sees | Root cause |
|---|---|---|
| Records filled in after the fact | Same handwriting and same ink across several weeks | Logs completed at the end of the month |
| Broken traceability | A finished lot cannot be traced to a mother plant | Codes restart at each stage |
| Missing days to harvest | Spray records with no interval to harvest | The field is missing from the form |
| Retest without investigation | A passing result filed on top of a failure | No out-of-specification procedure |
Most farms fail their first audit because of records, not growing. The crop was often grown well, but nobody wrote it down at the time.
What to do: Check your own forms against the four failure patterns in the table this week. Make sure each code carries through every stage and the spray form has a days-to-harvest field. Then add the out-of-specification procedure from section 11. These are the gaps auditors most often find on a first visit.
Has your farm been through a GACP audit? Whether you passed, failed or are still fixing findings, your details help other growers more than any summary of the guideline. What did the auditor check first? Which record were you missing? How long did the fixes really take? Quality managers and consultants who work with Thai and export farms: which finding do you see again and again, and which fix lasts? Please reply below this topic.
References for Part 2
- European Medicines Agency, Committee on Herbal Medicinal Products. Guideline on Good Agricultural and Collection Practice for starting materials of herbal origin, EMA/HMPC/246816/2005 Rev. 1 (adopted by the HMPC on 9 July 2025).
- European Pharmacopoeia. Monograph 3028, Cannabis flower, Supplement 11.5 (in effect from 1 July 2024).
- International Council for Harmonisation. ICH Q3D guideline on elemental impurities.
- ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories.
- California cannabis laboratory testing requirements (eight-category panel).
- Gwinn and colleagues (2023). Review in Frontiers in Microbiology on microbial and mycotoxin risks in cannabis.
- Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568.
- World Health Organization. WHO guidelines on good agricultural and collection practices (GACP) for medicinal plants.
This article is part of the Asiannabis Community educational series on cultivation standards, testing and export. It is general information, not legal or regulatory advice, and is meant for places where growing cannabis is legally permitted.