Can’t decide between buying autoflowering or photoperiod weed seeds? This guide has you covered.
Autoflowering and photoperiod cannabis seeds are the two main types available to growers, each with its own pros and cons. Photoperiod seeds produce plants that flower based on light cycles, while autoflowering seeds produce plants that bloom automatically with age. This guide breaks down the key differences—from how they flower to their size, potency, and ideal growing conditions—to help you choose the right type for your growing needs.
Flowering Process
Autoflowering plants begin flowering on their own after a few weeks of growth, regardless of light conditions. This automatic flowering trait comes from wild cannabis (ruderalis) genetics, allowing autos to start blooming with age alone. Photoperiod plants, on the other hand, only enter the flowering stage when they receive longer nights (extended darkness)—in nature this happens in the fall, and indoors growers must induce it by changing the light schedule.
Simply put, autoflowers have an internal timer for blooming, whereas photoperiod strains rely on seasonal light cues or deliberate light control by the grower.
Light Schedule Requirements
Because of these differences, the two types have distinct light needs. Photoperiod cannabis requires a strict cycle—typically about 18 hours of light per day for vegetative growth, then a switch to 12 hours of light and 12 hours of darkness to trigger flowering.
Growers must be careful to keep uninterrupted dark periods; any light leaks at “night” can stress photoperiod plants.
Autoflowering cannabis does not need a change in light cycle to bloom. Autos can be grown under constant light schedules (many growers use 18–24 hours of light daily from seed to harvest). They will flower under almost any reasonable light cycle, making them simpler: there’s no need to adjust timers or worry about providing 12-hour dark periods. This makes autoflowers very beginner-friendly in terms of lighting, since even a continuous light or a sunny windowsill can produce buds.
Sex of Seeds (Feminized vs. Regular)
When buying seeds, it’s important to know if they are feminized (grow only female plants) or regular (mix of males and females). Autoflowering seeds on the market are almost always sold as feminized seeds.
This means nearly all autoflower seeds will grow into bud-producing female plants—convenient for growers who don’t want to identify and remove males. Regular autoflower seeds (with both male and female) are hard to find, since breeders typically produce feminized autos and it’s challenging to use males for auto breeding.
Photoperiod seeds are widely available in both feminized and regular forms. If you buy regular photoperiod seeds, roughly half may be male, so you’d need to weed out the males to avoid pollination. Feminized photoperiod seeds eliminate that worry by giving all females. For most home growers, feminized seeds (auto or photoperiod) are preferred to ensure all plants produce usable buds.
Check out: Feminized vs Regular Seeds: Which to Buy?
Price
There is often a price difference between these seed types. Autoflowering seeds tend to be a bit more expensive on average than photoperiod seeds. This higher cost is due in part to the extra breeding work required to stabilize the autoflower trait and the convenience they offer.
Additionally, because most autoflower seeds are feminized, they include the added cost of the feminization process. Photoperiod seeds have been a standard for a long time and can accommodate any budget—you can find affordable options, especially if you opt for regular (non-feminized) photoperiod seeds.
In a nutshell, if cost is a big factor, photoperiod seeds (especially regular ones) are usually the cheaper choice, whereas autoflower seeds often come at a premium for their “automatic” convenience.
Check out: Top 10 Best Cannabis Seed Banks 2025
Potency (THC Content)
Many growers consider potency, usually measured by THC levels. Historically, autoflowers were less potent because ruderalis genetics have very low THC. Early autoflower strains produced smaller buds with relatively low THC compared to photoperiod strains.
Photoperiod strains have traditionally been the champions of high THC – most record-breaking potent strains are photoperiod plants, and in general photoperiod buds have had higher THC and CBD levels than autoflowers. However, breeding advances have greatly improved autoflower potency over the years.
Modern autoflowering strains can be quite strong, with some matching or even exceeding the THC content of average photoperiod strains. Even so, on average an autoflower might have slightly lower THC than a top photoperiod equivalent. For a buyer, this means if maximum potency is your priority, photoperiod seeds are often a safer bet.
If you’re okay with bud that is potent but perhaps not the absolute strongest, today’s autoflowers can still deliver a good high—just be sure to choose reputable modern auto genetics to get the best potency.
Check out: Best High-THC Strains to Grow
Plant Size and Height
The typical size of the plants is another key difference. Autoflowering plants tend to stay relatively small and compact. Thanks to their short life cycle and genetics, autos usually don’t grow very tall—many stay under 2-3 feet (60–90 cm) indoors, making them ideal for small grow spaces or stealthy setups. Their compact nature also means they can be grown in tight indoor tents or even on balconies without drawing much attention.
Photoperiod plants have the potential to grow much larger because they can vegetative grow for a longer time. If left unrestrained, photoperiod cannabis can become very tall (some can reach 6–10 feet or more outdoors) and quite bushy. Even indoors, unless training techniques are used, photoperiods can quickly outgrow a small space. The upside of this larger size is a greater yield (more on that later), but it also requires more room.
So basically, if you have limited space or need a shorter plant, autoflowers’ smaller size is a big advantage. If space and height are not an issue and you want bigger plants and higher yields, photoperiod strains offer that potential by growing much larger.
Check out: Best Short Weed Strains for Small Spaces
Grow Time (Speed to Harvest)
One of the biggest draws of autoflowering seeds is their fast grow time. Autoflower cannabis races from seed to harvest in a matter of weeks. Many autoflower strains are ready to harvest about 8–12 weeks after germination, with some ultra-fast autos finishing in under 8 weeks.
In practical terms, that means you could go from planting a seed to collecting buds in roughly 2 to 3 months. Photoperiod cannabis generally takes longer. Indoors, growers often veg photoperiod plants for 4–8+ weeks and then need ~8+ weeks of flowering, so the total time can be 3 to 4+ months from seed to harvest (and even longer if you vegetate for an extended period). Outdoors, a photoperiod seed planted in spring won’t be ready to harvest until fall when the natural light cycle shortens—often 5–7 months total growth.
In short, autos are the speedy option, great if you want a quicker turnaround or multiple harvests in a year. Photoperiods are slower to finish but can reward the wait with larger yields. If patience isn’t your strong suit or you have a short outdoor season, autoflowers allow you to harvest much sooner. But if you don’t mind the time and want a bigger harvest from each plant, photoperiods might be worth the extra months.
Check out: Fastest Flowering Strains to Grow from Seed
Cloning
Cloning means taking a cutting from a plant to grow an identical “copy.” Photoperiod cannabis plants can be cloned easily – you can take cuttings from a photoperiod mother plant and root them to produce genetic copies that will also remain photoperiod. This is a huge advantage for preserving a favorite strain or running a consistent crop, and it’s one reason photoperiod strains are favored by many experienced growers and commercial operations.
Autoflowering plants cannot be practically cloned. While you can physically take a cutting from an autoflower, it will continue along the same age timeline as the mother plant. In other words, an autoflower cutting will flower when it’s “time” (often immediately or very shortly after cutting), rather than reverting to vegetative growth. This means the clone won’t have time to grow and yield properly. Essentially, every autoflower plant is a one-off—to grow more, you must germinate new seeds each time, since you can’t keep mother plants or clone them for future use.
For a buyer, if cloning and preserving genetics is your goal, photoperiod seeds are the way to go. If you plan to grow from seed each time and don’t need clones, the cloning limitation of autos won’t be an issue—but it’s good to know you can’t propagate autos beyond the seeds you buy.
Resilience and Hardiness
Autoflowering strains are often praised for their resilience. Because they inherited traits from Cannabis ruderalis (a hardy wild variety from harsh climates), autos can handle challenging growing conditions better than many photoperiods. They are generally tough plants, with good resistance to diseases and pests, and they tolerate environmental stress (like cold or irregular light) relatively well.
In fact, autoflowers’ ability to flower without strict light schedules makes them less sensitive to light stress – for example, an accidental light leak at night won’t disrupt an auto’s flowering like it could a photoperiod. Many growers find that autos are forgiving and easier to keep alive, which is great for beginners. Photoperiod strains, while not necessarily flimsy, can be more sensitive to stressors. They demand consistent light/dark cycles, and interruptions or rough conditions can shock them (leading to issues like hermaphroditism or re-vegging).
Photoperiod plants often also require more attentive care with nutrients and environment to reach their full potential.
That said, a healthy photoperiod plant can certainly be resilient too, but they generally rely more on the grower’s skill to maintain ideal conditions. If you anticipate a less controlled environment or want a low-maintenance, sturdy plant, autoflowers have the edge in resilience.
If you’re confident in providing a stable environment and careful care, photoperiods can also thrive and reward you greatly.
Check out: Best Mold Resistant Cannabis Strains
Training and Techniques
Growers often use plant training techniques (bending, topping, etc.) to increase yields or control shape. Photoperiod plants are well-suited for various training methods. Because you can extend the vegetative phase, photoperiods can recover from high-stress training (HST) like topping, fimming, or main-lining, and they respond well to low-stress training (LST) like bending branches. In fact, photoperiod strains can handle even aggressive training when done properly.
You can top a photoperiod plant multiple times to create a bushier shape, use trellising (SCROG), and basically sculpt the plant over a longer veg period. This allows advanced growers to maximize yield and control plant height/shape precisely. Autoflowering plants are generally harder to train. Since autos rush from seed to flower, they have less time to recover from any stress. High-stress methods (like topping or heavy pruning) are usually not advised on autoflowers, as they could stunt the plant and reduce yields given the short lifecycle.
Some gentle low-stress training (for example, bending the main stem slightly to allow more even light exposure) can be done on autos, but even LST must be done early and carefully. Most growers of autos keep training minimal or skip it, letting the plant grow naturally. For buyers, this means if you plan to use lots of training techniques to boost yield or manage canopy, photoperiod seeds offer much more flexibility.
If you prefer a simpler grow with minimal training, or you’re a novice not comfortable with these techniques, autoflowers will do fine without heavy training—just know you can’t push them as hard in that regard.
Yield and Marketability
Yield and commercial appeal are often linked. Generally, photoperiod strains have higher yield potential per plant than autoflowers, due to their larger size and longer grow time. A single photoperiod plant, especially outdoors or with a long veg period, can produce a very large harvest (several hundred grams, even over a kilogram in ideal conditions).
Autoflowers, being smaller and faster, usually produce a smaller amount per plant—often around 50–100 grams (a few ounces) per plant under good conditions, though this varies.
For a commercial grower or anyone looking for maximum yield and potency, photoperiods are typically more appealing. They also allow cloning, which means a whole crop can be uniform and optimized, something important for market consistency. Additionally, photoperiod buds have a reputation for higher potency, which consumers and dispensaries often demand.
Autoflowering strains are usually favored by hobby growers or those who value quick turnaround over sheer yield. While modern autoflowers can yield decently and have good quality, they still usually produce less per plant and slightly lower THC than top photoperiods, which can be a drawback in a commercial setting.
Basically, if you’re growing for personal use, autos provide a fast, easy harvest that might be perfectly sufficient. But if you’re aiming for maximum yield, potency, or a commercial product, photoperiod seeds are generally the preferred route due to their bigger harvests and stronger buds.
Check out: Highest Yielding Cannabis Strains
Breeding Difficulty
If you’re thinking of breeding your own cannabis strains or producing seeds, photoperiod and autoflower seeds offer different challenges. Photoperiod plants are simpler to breed – any male and female photoperiod cross will yield offspring that are also photoperiod (since the photoperiod trait is dominant). You can also keep a photoperiod “mother plant” and use clones for breeding multiple generations. Autoflowering plants are notably harder to breed for a couple of reasons. First, the autoflower trait is genetically recessive, meaning when you cross an autoflower with a photoperiod, the autoflowering characteristic tends to be lost in the first generation.
It takes several generations of selective breeding (backcrossing offspring to autoflower parents, etc.) to stabilize the autoflower trait in new hybrids. In other words, you can’t create a new stable autoflower strain in one cross – it requires a lot of work and plant selection over multiple generations.
Second, as mentioned earlier, most autoflower seeds are feminized and don’t easily produce male plants, which complicates traditional breeding that relies on male pollen.
Breeders often have to induce female autos to produce pollen or find rare regular auto seeds. Because of these hurdles, developing new autoflower strains is more complex and time-consuming. For the average buyer, if your goal is to experiment with breeding, starting with photoperiod regular seeds is much easier. Breeding autos is possible but requires more expertise and effort to get that recessive auto-flowering trait to reliably pass on.
Check out: How to Breed Cannabis Seeds
Indoor vs. Outdoor Suitability
Both autoflower and photoperiod seeds can be grown indoors or outdoors, but each has certain advantages in different settings:
Indoor Growing: In small indoor grows or grow boxes, autoflowers shine. Their compact size fits in limited spaces, and the fact that they don’t need a strict dark period means you can keep lights on longer (even 24/7 if you choose) to maximize growth. You can even grow autos on an 18-hour light cycle in the same room as plants in vegetative stage, since autos will flower under those conditions and you don’t need a separate bloom tent.
Photoperiod plants indoors require you to have a completely dark period each day for flowering, so your grow space must be light-sealed and on a timer set to 12/12 when you want buds. This can be a bit more complicated for beginners or those without ideal setups. However, photoperiods indoors allow you to control veg time—you can keep them vegetating until they reach a desired size, then flower them. This means you can grow photoperiod plants big to get a higher yield, provided you have the space and proper lighting.
In summary, if you have a very small or simple indoor setup, autoflowers are more convenient (no need for light schedule changes). If you have a well-equipped indoor grow and want larger harvests and don’t mind managing light cycles, photoperiods can be very rewarding.
Check out: Best Indoor Cannabis Strains
Outdoor Growing: The choice here can depend on your climate and goals. Autoflowers outdoors offer the benefit of speed—they can finish in the middle of summer, allowing for multiple harvests in one season if you stagger planting.
For example, some growers plant autoflower seeds in spring and harvest by mid-summer, then start another round and harvest again by early fall. Autos are also great for regions with short summers, since they don’t need the full long season to produce buds. Their hardiness from ruderalis genes helps them withstand cooler temperatures and some rough conditions, which outdoor plants often face. Additionally, their smaller size makes them easier to hide in a garden or guerrilla grow.
Photoperiod plants outdoors typically grow much larger and yield more, but they require a longer season—they won’t flower until the natural daylight drops (around late summer/fall). In a warm, long-summer climate, photoperiods can grow into huge, tree-like plants and produce a very large harvest in the fall. In cooler or temperate climates, you have to choose photoperiod strains that finish early, or else frost/rain could hit before they are done.
You only get one harvest per year from photoperiods outdoors (unless using light deprivation techniques to force an early finish). For commercial outdoor operations or anyone seeking maximum yield per plant, photoperiods are preferred. But for a casual grower or someone in a challenging climate, autoflowers provide flexibility outdoors—you can harvest before bad weather, and even get successive crops within one summer.
Check out: Best Outdoor Cannabis Strains
All things considered, the best choice between autoflowering and photoperiod seeds depends on your needs and situation. If you want a quick, easy grow with minimal fuss (especially if you’re a beginner or have limited space), autoflower seeds might be ideal. They flower on their own schedule, stay small, and finish fast. If you prioritize maximum yield and potency, and you don’t mind a longer grow with more control required (or you want to practice advanced training and cloning), photoperiod seeds are the traditional choice that can deliver big results. By considering each aspect—from light requirements and timing to size, strength, and your personal goals – you can confidently choose the type of cannabis seed that’s right for your grow. Happy planting!
