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Autoflower plants start flowering on their own, after a few weeks of growth, whatever the light schedule. Photoperiod plants flower when the nights get longer: outdoors in late summer, or indoors when you switch the light to 12 hours on and 12 hours off. That single difference decides most of what follows: plant size, timing, training and how forgiving the plant is.
Seed types
Autoflower or photoperiod?
Same plant, two different clocks. Pick the one that fits your space and your season.
See autoflower seeds
The short answer
- Choose autoflower for a first grow, a small space, a short outdoor season or a quick harvest.
- Choose photoperiod (feminized or fast version) when you want control over plant size, the option to keep a mother plant, or a bigger harvest per plant.
Side by side
| Trait | Autoflower | Photoperiod |
|---|---|---|
| How it flowers | Automatically, after a few weeks of growth | When nights get longer, or when you set indoor lights to 12/12 |
| Seed to harvest | Usually about 10 to 14 weeks, depending on the strain | Longer, because you decide how long it grows before flowering |
| Plant size | Usually smaller and more compact | Can grow much taller; you control size by when you trigger flowering |
| Indoor light schedule | No change needed; many growers keep long days all the way through | Long days to grow, then 12 hours of light and 12 of dark to flower |
| Yield per plant | Usually lower | Usually higher, especially after a longer growth stage |
| Training | Gentle methods such as low-stress training | Handles topping, low-stress training and SCROG well |
| Cuttings (clones) | Possible, but clones flower on the same clock as the mother, so there is little point (see can you clone autoflower?) | Yes, you can keep a mother plant and take cuttings |
| Outdoors in Canada | Most are ready in August | September or October, depending on the strain; fast versions often finish in September |
A note on the numbers in this article: harvest dates, flowering times and yields are ranges, not promises. They vary depending on growing conditions: the grower, the method and the season's weather. "Mold resistant" means mold tolerant: less prone to mold and slower to be affected. No strain is 100% mold resistant. How we set these numbers →
The core difference
Who each one suits
Autoflower
Simple and fast
Compact plants, no light change, harvest in a few months.
Photoperiod
Flexible and bigger
Control over size, cuttings and larger plants, with more to manage.
Autoflower: when it makes sense
An autoflower does not wait for the nights to lengthen, so it suits growers who want a simple schedule and a quick result.
- It is the easiest place to start, and most beginners do well with it. See our seeds for beginners.
- Its compact size fits a small tent, a balcony or a discreet corner of the garden.
- It finishes well before the autumn frosts, which helps in a short Canadian season.
The trade-off is that an autoflower has less time to recover from mistakes. Heavy pruning, root damage or a stressful transplant can cost a larger share of its short life, so handle it gently and sow it where it will stay.
Photoperiod: when it makes sense
A photoperiod plant gives you more control, and more to manage.
- You decide how long it grows before it flowers, so you can fit the plant to the space you have.
- It responds well to topping and other training, which usually means more flower per plant.
- You can keep a healthy mother plant and take cuttings of the phenotype you like best.
The trade-offs are time and attention. Indoors you have to change the light schedule on purpose. Outdoors the plant must finish before the first hard frost, so choose the strain with your region in mind. Our feminized seeds are photoperiod plants.
Where fast version seeds fit
Fast version seeds are photoperiod plants bred to finish earlier. They keep the control of a photoperiod plant but aim to be ready sooner, which is useful outdoors when autumn arrives early. Browse our fast version seeds, or read our guide to the four types of cannabis seeds.
Decide in a minute
Pick by your situation
Planning an outdoor season? See our calendar for when to plant cannabis outdoors in Canada.
Common questions
Are autoflowers weaker than photoperiod plants? No. Potency depends mainly on the genetics of the strain, not on the type. An autoflower is usually smaller and has less time to recover from stress, so it needs gentler handling.
Do autoflowers need a 12/12 light schedule? No. They flower on their own, so you do not need to cut their light to trigger flowering. Many growers give them long days for the whole cycle.
Can I grow autoflowers outdoors in Canada? Yes. Plant them after the last frost; most are ready in August, which is well before the autumn cold.
Can I grow both types in the same space? Yes, but photoperiod plants need about 12 hours of darkness to flower, and autoflowers usually do better with longer days. Many growers keep them in separate spaces for that reason.
Which type should I choose for my first grow? Most beginners start with autoflower because the schedule is simple and the plant stays compact. Check the growing rules where you live before you plant anything.
