Indoor autoflower grow guide for beginners

Published Mar 11, 2019 10:38 a.m. ET

 Autoflowering, sure you have likely heard of it, but what does it mean? Autoflowering cannabis strains will automatically adjust from the vegetative stage to the flowering stage with absolutely no changes in lighting. This makes them appealing to growers looking for a foolproof seed that requires the least work. Autoflowering cannabis strains will also be ready to harvest early usually in as little as 60 days after they are started from seed.

Autoflowering grow cycle

The autoflowering grow cycle differs from any other cannabis plant due to its hastened finish meaning shorter stages and fewer adjustments required for lighting. There are three different stages in the life cycle of an autofloweringplant.

Post germination 8-12 weeks - The first stage in an autoflowering grow cycle lasts approximately 8-12 weeks. This is how long it takes the cannabis plant to fully establish itself before entering into the vegetative stage. Autoflowering plants should not be transplanted after this part of the cycle. Once seeds crack open and plant life begins it is necessary to provide sufficient lighting. While autoflowering cannabis strains can live on a bare minimum of only 5-7 hours of daylight per day, it is recommended to provide at least 18 hours. Some growers swear by 24 hours a day of light so if you don’t have a timer then don’t worry too much. You will just want to place your light fixture several inches further from the plant’s foliage to be sure nothing gets burned.  

Vegetative Stage 10-14 weeks - This stage of an autoflowering grow cycle is much more accelerated then their more traditional counterparts. Autoflowering plants will exit this stage within 30 days and begin blooming. The autoflowering plants will stretch out the most during this stage with most easily growing an inch or more in a day. To see the most effective results and speed this process up each plant should be grown in its own 10 liters to 20-liter pot and should be kept at a temperature of 25 degrees Celsius with a high humidity level of around 60%-70%. In the vegetative stage fertilizers and nutrients are essential. Adding nutrients along with constant adjustments of your lighting to avoid burning while the plant is skyrocketing in size are the two most significant requirement changes during this phase of the cycle. Expect massive growth and leave plenty of room at least ten inches between the plant’s foliage and any bulbs.

Flowering stage 12- 20 weeks - Autoflowering plants will take 45-60 days from when the first pistils and hair begin to appear to when the plant will be ready to harvest. The optimal temperature for autofloweringcannabis to flourish at this stage is 25 degrees Celsius with a humidity of 45%-55%. Lighting schedules will not need to be adjusted at all and will maintain the same as when you began. Fertilizer can be provided up until the last two weeks before harvest which is when flushingshould occur to ensure the bud is safe for ingestion once harvested.

Tips for growing autoflowering plants

  • Provide the most lighting possible.
  • Keep a safe distance between lights and plant foliage to prevent burning.
  • Grow indoors for optimal results.
  • Water frequently. Since an autoflowering cannabis strain grows so quickly, it will need a bit more water to do so. Misting is a great way to add extra water to your care regimen without risking root rot.
  • Use 20 liter or larger pots. An autoflowering plant requires space to stretch out its roots to establish its immune system. Insufficient room to grow will hinder the pace at which the plant grows and overall yield that will be produced.
  • Prune and train just like you would with any other marijuana plant. Autoflowering strains grow much faster during the vegetative stage making them perfect for growing methods such as the scrog method. The plant can recover faster making it hardy for those who want to manipulate the size of the buds or plant itself.

Pros and cons of using autoflowering cannabis


  • Rapid Growth
    Autoflowering strains can cut as much of half of the expected grow time necessary when compared to their alternatives.

  • Smaller, More Compact Plants
    Growers who only have a small space in which to grow will benefit significantly from an autoflowering strain. Since their overall life cycle is shorter, they do not usually end up as tall. The average autoflowering plant will reach a maximum of 1.5 feet tall.

  • Powerful Genetics
    Autoflowering cannabis seeds are made by breeding hand picked strains specifically for qualities that include hardiness. The majority of DNA used in the making of autoflowering plants is from those grown in the northern hemisphere that have a much shorter growing period and much cooler temperatures making them easy to care for.

  • Fast Harvest
    Autoflowering plants have a life cycle that lasts only a couple of months making them perfect for those wanting to pull off multiple yields each year with minimal effort and time.

  • Do Not Require Adjustment of Lighting
    Autoflowering plants can get by on as little as five hours of daylight but prefer 18+ hours and can even do well in full 24 hours a day. This makes them useful for those who don’t want to have to keep track of an ever-changing light schedule.


The size of an autoflowering cannabis plant can be both a positive and a negative feature. A smaller plant quite often translates to a lower yield. Since an autoflowering plant doesn’t grow as long, it will not grow as high. This is not always the case as some choose autoflowering seeds for specific growing methods such as SCROG which can easily manipulate a small plant into producing plenty of giant buds that are short but bountiful.

Autoflowering seeds require more light than your average marijuana plant which can be costly when considering the unavoidable spike in utility bills from running lights so frequently.

-Low THC Content
Autoflowering seeds are created using more northerly strains of marijuana. Unfortunately, the majority of these strains are not high producers of THC. This does not mean that you cannot have a high THC content autoflowering strain, it just means that the majority of autoflowering plants will be lower on average than most other non-autoflowering ones.

-Limited Strains
If you were hoping to get an autoflowering seed that contains the genes of your favorite strain than you will be disappointed to learn that the number of strains available with this feature is few and far between. If you are open to trying new strains than this isn’t so important but for those wanting to grow a specific plant for its individual qualities than autoflowering seeds likely may not be an option.

-Difficult to Transplant
Since autoflowering cannabis has such a short life cycle, just one small interruption in its focus can be enough to seriously hinder its health. Transplanting should never be done beyond the first couple of weeks after germination if you don’t want to severely stunt your plant’s growth. This makes autoflowering plants unless for those who wish to begin by growing indoors to later transplant and finish them outside.

  • More Expensive/ More Difficult to Obtain
    Despite some of the downfalls of autoflowering seeds, they have grown in popularity making some of them a bit more expensive to purchase. Since the strains available with this feature aren’t exactly common, many seed banks don’t carry or advertise them as they aren’t the biggest money makers.

In conclusion, autoflowering cannabis strains are neither better or worse than their counterparts and are more of a group of specific features that focus around a shorter time requirement before harvest. To know if growing one is right for you weighing the pros and cons alongside your particular needs and preferences to see if an autoflowering plant will provide you with the product you hope to achieve.


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