How Autoflowers and Photoperiods Actually Differ
The fundamental difference is in how flowering is triggered. Photoperiod plants — including most traditional cannabis strains — require a change in light exposure to switch from vegetative growth to flowering. Outdoors, this happens naturally as days get shorter in fall. Indoors, growers manually switch from 18 hours of light per day down to 12 hours to trigger budding.
Autoflowering plants contain genetics from Cannabis ruderalis, a subspecies native to northern latitudes where harsh winters forced the plant to evolve a different strategy: flowering based on age rather than light. An autoflower will begin forming buds 3–5 weeks after germination regardless of how much light it receives — no schedule change required.
This single difference cascades into most of the practical distinctions between the two: growing time, plant size, yield potential, training methods, and how much expertise is required.
Autoflowers: The Full Picture
The Case For Autoflowers
Modern autoflower genetics have evolved dramatically from the early ruderalis crosses of the 2010s. Breeders like Mephisto Genetics, Night Owl Seeds, and Ethos Genetics have produced autoflower lines with THC levels exceeding 25%, yields that compete seriously with mid-tier photoperiods, and exceptional terpene profiles. The "autoflowers are weak" reputation is genuinely outdated for premium genetics.
The practical advantages are real: 8–11 week seed-to-harvest allows multiple runs per year in the same grow space. Compact size (typically under 3 feet) is ideal for tent growers or anyone with limited vertical space. No light schedule management means fewer variables for beginners to get wrong.
The Limitations
Autoflowers can't be effectively cloned — clones of autoflowering plants don't reset the flowering clock, so a clone will flower at the same time as its mother regardless of size, often resulting in a tiny harvest. This means every grow starts from seed.
Training methods like topping and heavy LST (low-stress training) need to be applied earlier and more carefully — autoflowers have less time to recover from stress than photoperiods. Many experienced growers stick to LST and avoid topping for autos. And while premium genetics have closed the yield gap substantially, high-yielding photoperiods in a well-managed grow can still outperform most autos per plant.
Typical Autoflower Timeline
Photoperiods: The Full Picture
The Case For Photoperiods
Photoperiod plants give experienced growers maximum control. You can keep a plant in vegetative growth as long as you like — vegging for 8–12 weeks allows you to grow a massive canopy before switching to flower, dramatically increasing yield per plant. Techniques like SCROG (Screen of Green), heavy topping, and monster-cropping all work particularly well with photoperiods because the plants have time to recover and fill in gaps.
Cloning works perfectly with photoperiods. A well-maintained mother plant can produce unlimited clones, meaning you never have to buy seeds again once you've found genetics you love. This is how commercial operations work, and it's how many home growers cut long-term costs significantly.
The best photoperiod genetics still push the frontier on potency. Strains like Gorilla Glue #4, GMO, and Zkittlez have been refined through extensive photoperiod breeding programs, and their pheno-hunting depth is currently ahead of the autoflower world (though this gap is closing rapidly).
The Limitations
The 12/12 light requirement is a genuine complexity increase for beginners. Any light leak during the dark period can interrupt flowering or cause hermaphroditism — a plant that produces both male and female flowers and ruins a crop. Light discipline is non-negotiable. For indoor growers, this means a properly sealed grow space and strict schedule.
The time investment is substantial: most photoperiod grows take 4–6 months from seed, sometimes longer for high-yielding strains. Autoflower growers can harvest 2–3 times in that same period. For growers optimizing for harvests-per-year over harvest-per-plant, photoperiods can actually be less efficient.
Typical Photoperiod Timeline (Indoor)
Full Comparison Table
| Category | Autoflower | Photoperiod |
|---|---|---|
| Seed to Harvest | 8–11 weeks | 4–6 months |
| Light Schedule Needed | No ✓ | Yes (12/12 to flower) |
| Plant Height | 1–4 feet typical | 3–10+ feet |
| Yield Per Plant | 1–5 oz typical | 3–20+ oz with training |
| Harvests Per Year | 3–5 indoors | 1–2 indoors |
| Beginner Difficulty | Easy | Moderate |
| Cloning | Not practical | Works great ✓ |
| Training (Topping/LST) | LST ok, topping risky | Full training ✓ |
| Outdoor Growing | Excellent ✓ | Good (season-dependent) |
| THC Potential | Up to 30%+ (top genetics) | Up to 35%+ (top genetics) |
| Seed Cost | $8–$25/seed | $6–$20/seed |
| Best For | Beginners, limited space, multiple runs | Max yield, cloning, full control |
Which Should You Choose?
No light schedule to manage, faster results, more forgiving of mistakes. Start with an easy-rated autoflower from Mephisto or a beginner strain from ILGM. Learn the basics, then decide if you want to try photoperiods.
Compact size and fast cycles are perfect for 2x2 to 4x4 tents. Multiple harvests per year in a small footprint. Top autoflower genetics will maximize your yield-per-square-foot-per-year better than most photoperiod setups.
Autoflowers shine outdoors — they flower regardless of daylight hours, can be harvested before summer ends, and their smaller size aids discretion. You can run 2–3 outdoor auto cycles per season in warmer climates.
If raw yield per harvest is your goal and you have the space to veg plants large, photoperiods win. A well-trained photoperiod in a 4x4 tent can exceed what most autoflowers produce in the same space per harvest — though total annual yield may still favor autos running 4 cycles.
If you find a special phenotype you want to keep forever, photoperiods are the answer. Clone it, maintain a mother plant, and you have those genetics indefinitely. Autoflowers can be re-seeded but not cloned effectively.
If you love running multiple phenos, training aggressively, and maximizing quality at the expense of time — experienced growers typically gravitate toward photoperiods for the control they provide.
Best Genetics by Type
Top Autoflower Breeders
The community standard for premium autoflowers. Every Mephisto release is extensively community-tested. Sold through NASC and Multiverse Beans domestically. Expect 65–85 days, exceptional terpene profiles, and yields that rival mid-tier photoperiods.
Known for pushing the flavor frontier on autoflowers. Their drops sell out fast and are highly sought by collectors. Available through NASC. If you see a Night Owl drop, grab it — restock windows are short.
More widely available internationally. Solid, reliable genetics across a large catalog. Good for beginners who want established autoflower strains without chasing drops. Available at Herbies and Seedsman among others.
Strong both in autoflower and photoperiod. Their Mandarin Cookies autoflower line is particularly respected. Available through NASC. Higher price point reflects the pedigree.
Top Photoperiod Breeders
Award-winning European breeder known for LSD, Pineapple Chunk, and their CBD lineup. Original packs available through Seedsman and Herbies. Consistent quality across decades.
American breeders who brought OG Kush and Sour Diesel genetics to commercial availability. Their Reserva Privada line includes some of the most influential photoperiod genetics ever released.
Wedding Cake, Jealousy, Ice Cream Cake — much of the modern cookie era traces to Seed Junky. Highly sought-after, limited availability. Check NASC for drops.
Known for Kimbo Kush, Grease Monkey, and a deep catalog of exotic crosses. Popular in the US enthusiast community. Periodically available through NASC.