How to Grow Better Autoflowers
Despite what you may have heard, autoflowering cannabis plants are awesome, and can outperform photoperiod strains in some conditions.
Autos can be tricky to grow. I have cultivated thousands over the past decade or so and I have learned a few things.
If you have a few minutes to spare, I am happy to share some tips that will improve your odds for autoflower glory.
Autoflower vs. Photoperiod
The Ruderalis Story
Lowryder Strain
Autoflower Breeding
Feminized Seeds
Seed Germination
Auto Seedlings
Autoflower Light Cycle
Growing Autos Indoors
Growing Autos Outdoors
Root Expansion
Autoflowers FAQ
Autoflower vs Photoperiod
Most cannabis plants are short-day plants, and will continue to grow vegetatively until flower development is initiated by a change in photoperiod.
Photoperiodism is an important trait for cannabis production in controlled environments.
This trait enables growers to initiate flowering at the optimal time for canopy management by manipulating the light cycle.
Photoperiod plants can be cloned, and many identical copies of the same plant can be grown.
This is important for consistency in commercial production, as cannabis plants grown from seed have natural phenotypic variation.
Autoflowering strains are Day-Neutral (DN) and will begin flowering automatically about three to four weeks after they are planted regardless of the photoperiod.
The Ruderalis Story
Ruderalis is the black sheep of the cannabis family, living in the shadow of its famous Indica and Sativa siblings. This sub-species of cannabis is defined by its Day Neutral flowering characteristic.
These wild-type, or uncultivated populations evolved at higher latitudes and developed the autoflowering trait as an adaptation to short growing seasons.
This feature enabled ruderalis plants to expand their range to above 50 degrees North and they continue to thrive in Siberia.
Wild ruderalis populations tend to have very low THC content. THC biosynthesis in cannabis is largely the result of human selection and ruderalis remained uncultivated until very recently.
Lowryder Strain
Most modern autoflower varieties are descended from the Lowryder strain, one of the first to exhibit stabilized DN flowering.
Although its pedigree is uncertain, Lowryder is likely the result of hybridizing ruderalis with sativa subspecies.
Lowryder displayed a short stature and modest THC and terpene production, allowing it to be fearlessly cultivated in the closets of college dorms.
Lowryder also inherited many undesirable traits from its wild ancestors and was pretty terrible to smoke.
From this humble source, the DN flowering trait has been ingressed into drug cannabis varieties over many generations.
Autoflower Breeding
Ingression is the breeding method that is used to bring desirable traits into a variety while excluding undesirables.
This is achieved by hybridizing, or cross breeding a variety containing the trait of interest, to a commercial variety of known quality. The progeny of this union are inbred until the desired trait is fixed, then back-crossed again to the commercial variety.
This cycle is repeated until the improved variety resembles the commercial one in every aspect except that the trait of interest has been ingressed. This process can take years.
Great improvements have been made to autoflower strains through repeated hybridization and backcrossing over a few decades.
Some autoflower varieties now exhibit cannabinoid and terpenoid profiles that are comparable with elite Photoperiod cultivars, but the perception that autos are schwag persists.
Feminized Seeds
Cloning Autos is impractical, as the “clock” regulating flower initiation continues to tick while cloning.
You can get a cutting to root, but the clone will start flowering as soon as it is rooted.
Autoflowers are always propagated from seed which has some drawbacks for commercial production.
Cannabis is usually dioecious, meaning that male and female flowers occur on separate plants.
In these populations, male plants must be culled promptly to prevent the pollination of sinsemilla crops.
Currently there is a high level of variability in many cannabis varieties propagated from seed. You never know what your going to get.
Most of these issues can be avoided through the selection of quality feminized seeds.
Purchasing your seeds from a reputable breeder is always a good investment. Phenotypic consistency, and stable gynoecy (no hermies) can vary greatly among seed lots depending on the breeder’s selection and feminization protocols.
Autoflowers have made me a better grower.
Continuous crop momentum from seed to harvest is required for autoflowering plants to reach their full potential.
Seed Germination
I keep my auto seeds in the fridge to improve germination ratios.
This is known as cold stratification and mimics winter conditions.
When seeds are removed from cold storage, dormancy is broken, and germination promoted.
This type of storage will benefit germination ratios of many seeds but is particularly important with autos due to their northern pedigree.
Autoflower seeds can be germinated in plugs, and transplanted at the first true leaf set, or sown directly into their final pots.
Auto Seedlings
Autos will flower spontaneously if rooting is restricted, often with comical results. I have seen plants literally lollipop and develop a single nug on a four-inch stalk.
Autos are in a hurry, and don’t have time to recover from stress or transplant shock. Low Stress Training (LST) techniques can be applied, but it is best to avoid topping autoflowering plants. LST involves bending plants so that lower branches are encouraged to develop due to a shift in hormone balance. This can increase the number of top colas produced by your plants.
Autoflower Light Cycle
Autoflowering cannabis plants will begin flowering a few weeks after germination regardless of the light cycle.
Autoflowers evolved to flower under long days, and will perform at their best with 18-20 hour photoperiods.
Plant performance is based on the total light over a given photoperiod, or the Daily Light Integral (DLI).
The DLI is calculated by multiplying the light intensity by the photoperiod. Autoflowering with an 18-hour photoperiod allows for 50% higher cumulative DLI than a 12-hour photoperiod using the same light source.
This means that autos can thrive under lower light intensities.
In addition to greater yield, a high DLI supports dense flower formation, and elevated cannabinoid and terpenoid biosynthesis.
Growing Autoflowers Indoors
Autoflowering cannabis plants offer several advantages for home growers.
For small grow chambers or tents, it can be much easier to maintain a stable climate when lower wattage lights are run continuously, rather than cycling more powerful lights on and off.
For growers with sub-optimal lighting conditions, increasing the photoperiod can increase flower quality and yield.
Autoflowers can be planted regularly for a continuous harvest of meds from the same grow chamber.
Lighting timers are not required, and light pollution will not affect your plant’s flowering stage.
Growing Autoflowers Outdoors
After a few decades of growing weed here in B.C. Canada, I choose to grow autoflowers in my outside gardens. My nicest plant last year yielded 7 ounces of terpene rich bud in mid August.
For commercial farmers autoflowers offer several advantages over photoperiod crops.
At temperate latitudes, successive crops can be cultivated over a single growing season without the need for light-dep infrastructure.
At more northern latitudes, all crops can be timed to ripen during the peak solar window, increasing quality and yield, and enabling harvest before elevated seasonal pathogen pressures occur.
Regardless of latitude, the autoflowering trait allows for harvests over an extended period. This enables more efficient use of labor and processing infrastructure and can provide market timing advantages for finished products.
Root Expansion
Cultural systems that permit unrestricted root expansion will result in larger plants.
In commercial settings tight planting densities and minimal pruning contribute to higher yields.
Autos are generally not heavy feeders, and sensitive to a high ec in the root zone, so moderate feeding schedules are recommended.
I achieve the highest productivity per area by planting two plants in each pot.
This might seem crazy, but it allows the use of larger pots for root expansion while increasing overall biomass production.
I have grown two plants per 10 gallon pot, 2 plants in separate 5 gallon pots, and one plant per 10 gallon in greenhouse trials, and 2 plants per pot easily outperformed the other iterations.
Autoflowers FAQ
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Most autoflowering plants require between 70 to 100 days to mature after seed germination.
Cannabis seed breeders should be able to provide an estimated time to harvest for the strains they sell.
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Yes, autoflowers can be cloned, but they will continue to flower as they are rooting, and produce a very small yield.
The best way to propagate autoflowering strains is to germinate feminized seeds.
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Autoflowering seeds can be regular or feminized.
Feminized seeds are always recommended for home growers.
There is no reason to waste time growing male plants that have to be culled before they pollinate the neighborhood.
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Yes, all cannabis populations can produce some hermies, or intersex plants.
In well made feminized seeds, a few plants per thousand will produce male flower parts.
It is important to inspect your plants for signs of hermaphroditism during early flower to avoid this possibility.
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Yes, many autoflower strains now have THC levels well above 20%.
The best autoflowering strains have 2-4% terpenes, dense nugs, and a complex flavor profile.
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Autoflower yields will vary depending on the strain and growing conditions.
My largest outdoor auto yielded seven ounces of sticky bud in August last year.
Most home growers should expect 1-4 ounces of yield per plant.
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Yes, autos can be transplanted if you are careful.
Autoflowering cannabis plants are in a hurry, and don’t have a chance to recover if they experience transplant shock.
Most growers will benefit from germinating seeds in their final pots to avoid this issue.
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No, topping autoflowers is not recommended.
Autos have a short lifecycle and will benefit from Low Stress Training (LST) techniques that don’t slow down growth.
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Yes, autoflowers can be lightly pruned.
This will increase airflow through the plant and focus the plant’s energy on the flower sites that are getting the most light.
Autoflowering cannabis plants should only be pruned when they are well rooted, and no more than 10% of plant biomass is removed in one session.
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Yes, autoflowering plants can perform very well outdoors.
Autos are the only strains I will grow in my family garden here in B.C, Canada.
Growing autoflowers allows me to time my harvest for the best summer weather in my area.
