Three seed types are used in cannabis growing. Regular seed gives about half male and half female plants. Feminized seed gives about 99% females. Autoflower seed carries Cannabis ruderalis genes and starts flowering by plant age, whatever the day length. This part covers the practical side of choosing and keeping seed.
It covers four things: how far new autoflower lines have come, how to judge a seed seller, how to store seed so it still germinates years later, and which type suits which purpose. The Thailand and Southeast Asia notes deal with heat, rainy-season humidity, power cuts and buying seed legally.
This is Part 2. Part 1: Seeds: Regular vs Feminized vs Autoflower — Comprehensive Comparison 2025
6. New-generation autoflowers (2024–2026)
Older autoflowers were seen as weaker plants. Since 2020, leading breeders have produced autoflowers that match or beat some average photoperiod strains on potency, yield and terpene profile. Terpenes are the compounds that give cannabis its smell and taste. Most new-generation autoflowers are reported at 20–28% THC. One breeder-reported test gave 31.8%. Topic 1384 looks at whether autoflowers have caught up with photoperiod plants overall.
6.1 Reported potency figures
The original article listed five strains as results from the American Autoflower Cup 2025, a competition for autoflower strains held in Los Angeles (USA). The forum editors could not find these entries on the official 2025 results page. Only the one figure that could be traced to a source is kept below. It was not checked against a laboratory certificate (a certificate of analysis is the lab’s test report for a sample).
| Strain | Breeder | THC (%) | Total cannabinoids | Notes |
|---|---|---|---|---|
| Double Grape | Mephisto Genetics | 31.8% | 36.93% | The breeder’s own report (January 2024) on one plant grown in Oklahoma, USA. Not a competition result. The breeder calls it possibly the highest-tested autoflower, with a question mark. |
Translator’s note: A published THC figure comes from one sample grown under one set of conditions. Plants grown in Thai heat and humidity may test differently. THC is also only one measure of quality. If a seller quotes THC figures, ask which lab tested the sample and when.
6.2 Breeders named in the original article
The list below repeats what the original article says about each breeder. It is not a recommendation. The forum editors have not tested these lines.
- Mephisto Genetics: described in the original article as an early specialist in high-quality autoflowers. Releases come in small limited batches, and the breeder has an active grower community. Strains named: Double Grape, Mango Smile, Forum Stomper, Alien vs Triangle.
- Night Owl Seeds (Daz): Daz is the breeder behind Night Owl Seeds. The original article describes his lines as known for their terpene profiles. Strains named: Mango Isle, Sourdelica, Blue Microverse.
- 420 Fast Buds: a wide range of strains at lower prices. The original article presents it as suited to beginners. Strains named: Gorilla Cookies Auto, Wedding Cheesecake Auto, Strawberry Pie Auto.
- Ethos Genetics: works on both autoflower and photoperiod lines. Strains named: Mandarin Cookies Auto, Planet of the Grapes Auto.
- Dutch Passion: a seed bank formally founded in 1987. The original article describes its autoflower lines as stable. Strains named: Auto Ultimate, Auto Mazar.
Translator’s note: Well-known strain names get copied, so a pack sold under a famous name may contain different genetics. If a breeder has an official distributor in Thailand, ask the breeder to confirm who it is before you buy. Topic 1457 explains how to check a Thai seed vendor.
6.3 Why autoflowers improved so fast
- Repeated backcrossing. Backcrossing means crossing the offspring back to the same elite parent again and again. After 6–8 generations of crossing with elite indica or sativa plants, the ruderalis genes add mainly the autoflowering trait. THC, terpenes and yield come from the high-quality parents.
- Phenotype hunting at large scale. Breeders such as Mephisto grow thousands of plants per batch to select the best individuals.
- Lab testing. HPLC (high-performance liquid chromatography) and GC-MS (gas chromatography–mass spectrometry) are lab methods that separate and measure individual compounds. They let breeders measure cannabinoids and terpenes precisely and select on the results.
- Shared grower data. Thousands of growers post their results on Reddit groups such as r/MephHeads and r/Autoflowers. Breeders read these results and adjust their selection.
What this gives you as a grower: autoflowers are now a serious option for quality, not only for speed. How the new lines perform at 30–35 °C and high humidity is still not well documented (see topic 1459).
What to do: Grow a small trial of 2–4 plants of one new-generation autoflower next to your usual strain, in the same space and season. Record days to harvest, dry weight and any mould or heat damage. This shows whether the line suits your conditions before you commit a full room.
7. How to judge a seed bank
A seed bank here means a business that sells seed from one or more breeders.
7.1 What to check
| Criterion | What to look for | Importance |
|---|---|---|
| Trading history | 5+ years of continuous trading, a clear address | Very high |
| Germination guarantee | A written promise of 80–90%+ germination, or replacement seed | Very high |
| Range | Several seed types (regular, feminized, autoflower) and several breeders | High |
| Transparency | Published parentage, THC/CBD %, growing guides | High |
| Customer reviews | Genuine reviews on several independent platforms | High |
7.2 Warning signs
- No history or address: a new website with no legal company information.
- A 100% germination guarantee: no batch of living seed germinates 100%, so the promise cannot be true.
- Only positive reviews: the reviews are probably fake.
- Very low prices: the seed may be fake, old or wrongly labelled.
- Payment by cryptocurrency only: you have no way to get a refund.
Translator’s note: Read topic 1458 on what is legal when buying cannabis seed in Thailand before you order, especially from abroad. Old stock is a real risk in a hot climate, because seed stored warm loses germination faster (see section 8). Seed is not automatically disease-free: hop latent viroid (HLVd) can pass through seed. For real experiences with specific sellers, ask in the Seeds and Genetics Trading section of the forum.
What to do: Before ordering, score the seller against the five criteria and five warning signs above. Keep the receipt and photos of the sealed pack. Germinate a few seeds early to check the promised rate. You will then have the evidence needed to claim replacement seed.
8. Seed storage and long-term viability
Stored correctly, cannabis seed can still germinate after several years. Three things shorten its life: humidity, heat and light.
8.1 Storage conditions
| Factor | Best level | Avoid | Why |
|---|---|---|---|
| Temperature | 4–8 °C (refrigerator) | Above 25 °C, or freezing seed that is not fully dried | In moist seed, freezing forms ice crystals that damage seed cells. Genebanks freeze only seed dried to low moisture |
| Humidity (RH) | 20–30% | Above 40% or below 10% | Too moist leads to mould. Too dry makes the shell brittle and cracked |
| Light | Complete darkness | Direct light, UV | UV damages the structures inside the seed |
| Container | Airtight amber glass jar | Ordinary plastic bags | Glass does not let gas or moisture through. Add silica gel (a drying agent) |
8.2 How long seed stays viable
The figures below are the original article’s rough estimates, not measured data.
| Storage conditions | Expected germination | Maximum period |
|---|---|---|
| Room temperature (20–25 °C), low humidity | 80–90% | 1–2 years |
| Refrigerator (4–8 °C), sealed jar with silica gel | 90–95% | 3–5 years |
| Dedicated cool store with humidity control | 85–95% | 5–10 years |
| Seed over 5 years old, poor conditions | 30–60% | Falling |
Translator’s note: Indoor temperatures in Thailand are often 30–35 °C. That is above the 25 °C limit in the table, so the “room temperature” row does not describe a Thai room. Seed kept on a shelf here should be expected to last less than the 1–2 years shown. A refrigerator is the practical choice.
Translator’s note: In the rainy season, humid air condenses on a cold jar. Let a jar from the fridge reach room temperature before opening it, and open it in a dry or air-conditioned room. Keep jars at the back of the fridge, not in the door, where temperature swings each time it opens. During a power cut, keep the fridge closed; a sealed jar inside a closed fridge stays cooler. Use silica gel that changes colour, and replace or re-dry it when the colour changes. Topic 1405 covers seed and pollen storage in more depth.
8.3 Practical steps
- Put seeds in small zip bags with silica gel packets. Place the bags in amber glass jars and keep the jars in the refrigerator.
- Do not open and close the same jar again and again. Split your seed into several small jars, so each opening exposes only a few seeds.
- Test old seed before planting. For seed more than 3 years old, germinate 2–3 seeds before sowing a full batch. Soaking for 24 hours in warm water and then placing the seeds on a wet paper towel often helps old seeds germinate.
What to do: Label each jar with the strain, the date bought and the date stored. When seed passes 3 years, run the 2–3 seed test before each sowing. This tells you whether to sow extra seeds to make up for lower germination.
9. Choosing seed by purpose
| Purpose or situation | Recommended seed type | Reason |
|---|---|---|
| Beginner, first grow | Autoflower (feminized) | Easy to grow, fast harvest, tolerates mistakes |
| Maximum yield indoors | Feminized photoperiod | Size control, high yield, high potency |
| Several crops a year outdoors | Autoflower | 8–11 weeks per cycle, 3–4 crops a year in tropical climates |
| Breeding, new strains | Regular | Males needed for pollen; varied gene pool |
| Phenotype hunting | Regular or feminized | Regular gives more variety. Feminized saves space (no males) |
| Small hidden space | Autoflower | Small (60–120 cm), short life cycle |
| Medical use, high potency | Feminized photoperiod | Highest THC/CBD, best control |
| Strain preservation, gene bank | Regular | Keeps the natural gene pool |
| Outdoors in harsh climates | Autoflower | Ruderalis genes resist cold and stress |
| Large-scale commercial | Feminized photoperiod | Uniform, predictable yield, quality control |
Translator’s note: In Thailand and Southeast Asia, the hard outdoor conditions are heat and rain, not cold. The “harsh climates” row is about cold tolerance, which tells you little about performance here. For outdoor photoperiod crops, remember the early-flowering effect of roughly 12-hour days (topic 1447). For medical or commercial production, the seed choice comes after the licence question. Every flower-production plan must fit the Thai rules below.
What to do: Find the row that matches your main purpose and write down the seed type. Then run one small batch before you scale up. This tests the choice in your own space, climate and budget.
Legal context
This article is educational information for lawful medical and agricultural purposes. Cultivating cannabis requires a licence under the laws of your country or territory.
In Thailand, cannabis flower (ช่อดอกกัญชา) is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568, in force since 26 June 2025 (topic 1515). Flower may be sold only against a PT 33 (ภ.ท.33) prescription covering at most 30 days. Advertising and online sale of flower are prohibited.
The Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569, in force 30 April 2026, tightens the licence criteria for cannabis flower. Under the Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569, in force 26 April 2026, licences for extracts above 0.2% THC go only to state agencies, the Thai Red Cross Society, and Thai juristic persons that are not “foreign” under the Foreign Business Act B.E. 2542. The draft Cannabis Control Act is not yet law.
The forum does not allow direct sales, does not promote recreational use, and does not publish content aimed at countries where cannabis is prohibited.
If you have trialled a new-generation autoflower in Thai conditions, or stored seed through a rainy season, post your results below this topic. Questions are welcome here as well.
References
- American Autoflower Cup (2025). CUP 2025 winners. Los Angeles, CA. Winners 2025
- Mephisto Genetics (2024). Strongest Autoflower in the World?! Strongest Autoflower in the World?! – Mephisto Genetics
- Dutch Passion (2021). How to Store Cannabis Seeds the Right Way. How to Store Cannabis Seeds the Right Way | Dutch Passion
- Royal Queen Seeds (2020). Regular Vs. Feminized Vs. Autoflowering Cannabis Seeds. Regular Vs. Feminized Vs. Autoflowering Cannabis Seeds - Royal Queen Seeds USA