Growing Autoflowers

Growing Autoflowers

Growing auto flowering varieties has become quite popular amongst the new generation of hobby growers due to their fast turnaround and compact size, making them ideal for many new and experienced growers.

Auto flowering varieties completely mature from seed to harvest in 8-12 weeks, which means they are not subject to photoperiodism.

Autos are Day-neutral plants which means they flower without regard to photoperiod.

Plants like canna (short-day plants) flower without an inductive photoperiod, the induced photoperiod merely causes flowering to occur sooner, this is known as facultative photoperiodism.

Short-day plants vegetate best when the daylight hours are extended beyond normal. When the day hours are longer, the P-fr (Far-red) stores, cannot fully decay before the light comes back on, keeping the plant in a vegetative state.

Short-day plants exposed to a longer dark period (12+ hours) are able to fully decay their built-up stores of p-fr, which initiates phytochrome to trigger flowering.  

For some plants, the requirement for a dark period is absolute, they are classified as long-night plants and they will not flower until exposed to long nights, this is known as obligate photoperiodism.



  • Despite popular belief, you can start your seedling in a much smaller pot than the suggested final container.
  • Germinate the seed in preferred starter plug/cube. (See germination tutorial)
  • Once the seed has its first pair of serrated true leaves transplant the plug to a 100ml pot using coco: perlite mix (70:30)
  • The seedling will thrive in this pot over the next 7-14 days
  • Once the seedling has developed a nice root ball we now transplant to the final pot very carefully (Always wear gloves)
  • Now the plant is in its final pot we must feed daily, obviously, we want a moist pot, not saturated, if it is saturated then only feed small amounts of food, and try to encourage consumption.



  • Week 1 - 2 Medium light exposure (18/6)
  • Week 3 – 10 High light exposure (16/8)
  • Week 10 – 12 Medium light exposure (12/12)


*Note: Germination (7-10 days) low light levels, ideally T5 lighting. (20/4)



Like any plant we are feeding, we don’t go straight to the max dose, rather a gradual build of nutrition, relative to the growth of the plant.

Over the entire grow most Auto’s will generally not consume an EC above 1.8, in fact an EC higher will create the exact opposite of the intended outcome.

Less is more with Auto’s, for example here is a chart that should help you understand the building blocks of an auto;

The food should be kept simple:

  • A/B Base nutrients
  • Cal/Mag/Iron
  • PK


WEEK 1-4

EC 0.6-0.8 – pH: 5.8-6.0

WEEK 4-6

EC 0.8-1.2 – pH: 5.9-6.1

WEEK 8-9

EC 1.2-1.8 – pH: 5.9-6.2

WEEK 9-11

EC 0.8-1.0 – pH: 6.0-6.2


EC 0.0-0.3 – pH: 6.0


Selecting how many plants, really does determine the end result especially if weight is a concern. Growing regular photoperiod varieties in this space is vastly different in comparison, one plant will fill this space quite effectively whereas most Auto’s will not.

The numbers are always a preference, so always do what is comfortable for your current situation. Most would grow 4-6 in this space, be aware that lower numbers may not fill the space as effectively.

Happy growing, please share this tutorial around if you think it will help someone in this situation!


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Growing Autoflowers
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How To Grow Food Indoors
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