Photoperiod Seeds
Cannabis strains within this subcategory are defined by their reliance on changes in light cycle to initiate flowering. The classification is based on flowering behaviour rather than genetic lineage or cannabinoid profile, with photoperiod strains represented across both Feminized Seeds and Regular Seeds, and encompassing a broad range of genetic expressions shaped by individual breeding lines.
Read MoreWho Are Photoperiod Cannabis Seeds Best For?
Photoperiod seeds are ideal for growers who want maximum control over their plants. They suit indoor growers with timers and grow lights, outdoor growers with enough season length, and anyone looking to train larger plants for higher yields.
They’re less suitable for growers who want a fast, low-maintenance grow with minimal intervention — in those cases, autoflowering seeds are often a better fit.
What Are Photoperiod Cannabis Seeds?
Photoperiod cannabis seeds grow based on light schedules — the term “photoperiod” simply refers to how a plant responds to changes in daylight. These strains remain in the vegetative stage as long as they receive long periods of light and only begin flowering once daylight hours are reduced.
Indoors, this means starting plants on a 16–18 hour light cycle to simulate summer, then switching to 12 hours of light and 12 hours of darkness to initiate flowering. Outdoors, photoperiod plants naturally begin flowering as days shorten toward the end of summer.
Why Choose Photoperiod Cannabis Seeds?
The main advantage of photoperiod seeds is control. Because the flowering stage doesn’t start until you change the light cycle, you decide how large and developed your plants become before bloom begins.
This makes photoperiod strains well suited to:
- Training techniques such as topping, LST, and SCROG
- Cloning and maintaining mother plants
- Growers aiming for larger plants and higher yields
With a longer vegetative phase, plants have more time to build strong roots and structure, which supports heavier flowering later on.
How Long Do Photoperiod Seeds Take to Grow?
Photoperiod seeds grow at the pace you set. Plants can be flipped into flower after as little as six weeks of vegetative growth, or kept in veg longer to increase size and yield potential.
Flowering time depends on genetics. Indica-dominant strains usually finish faster, while sativa-dominant strains often require longer flowering periods. Total grow time varies based on strain choice, grow environment, and how long plants are kept in veg.
When Should You Switch From Vegetative Growth to Flowering?
Plants are generally ready to flower once they’ve developed a healthy root system and a strong canopy with multiple bud sites. Because photoperiod plants often stretch after the light cycle changes, growers usually flip to flower when plants reach around half to two-thirds of their final desired height.
The key benefit here is flexibility — you decide when your plants are ready, rather than being locked into a fixed timeline.
Advantages of Growing Photoperiod Seeds
Compared to autoflowers, photoperiod strains offer:
- Greater control over plant size and structure
- Higher yield potential per plant
- Better suitability for training and cloning
- Flexibility if early growth is slow or interrupted
If conditions aren’t ideal early on, plants can simply remain in veg longer until they’re ready to flower.
Are Photoperiod Cannabis Plants More Potent?
Photoperiod strains are often associated with higher THC levels than autoflowers. Autoflowering genetics include cannabis ruderalis, which enables automatic flowering but can limit potency. Photoperiod plants typically have longer flowering times, allowing more opportunity for cannabinoid and terpene development, depending on genetics and growing conditions.
What Light Cycle Do Photoperiod Seeds Need?
During the vegetative stage, photoperiod plants are usually grown under 16–24 hours of light per day. This can be maintained indefinitely as long as the cycle remains consistent.
To trigger flowering, the light cycle is reduced to 12 hours of light and 12 hours of uninterrupted darkness. This signals to the plant that autumn has arrived, initiating flower production.
Do Photoperiod Seeds Need Special Lighting?
Outdoors, no additional lighting is required — the sun provides everything needed. Seeds are best planted in late spring or early summer to maximise vegetative growth before flowering begins naturally.
Indoors, growers need quality grow lights and timers to control light cycles accurately. Full-spectrum lighting that mimics natural sunlight delivers the best results through both veg and flower stages.
How Much Do Photoperiod Cannabis Plants Yield?
Under ideal outdoor conditions, some photoperiod plants can produce very large yields, with experienced growers reporting harvests well over 1kg per plant from high-yielding genetics. Indoors, yields depend heavily on plant size, training methods, and environment.
Because photoperiod plants can be kept in the vegetative stage for longer, they often produce higher yields per plant than autoflowers — provided space, lighting, and care are sufficient.
How Should Photoperiod Seeds Be Stored?
To maintain long-term viability, photoperiod seeds should be stored in a cool, dark, and dry environment. An airtight container kept away from heat and moisture helps preserve germination rates for future grows.
Are All Photoperiod Seeds Feminized?
No. “Photoperiod” refers only to how a plant flowers, not its sex. Photoperiod strains are available as both feminized and regular seeds, allowing growers to choose based on their breeding or cultivation goals.
