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Guide to Growing Autoflowering Cannabis

Four Stages of Growth in Fast Forward

Autoflowering cannabis cultivation always starts from seed. Let’s be perfectly clear and get this straight from the outset: you can’t crop autos from clones. Sure, you can take a cutting from a mature autoflowering plant and probably get it to take root too. But that little shrub will never grow to a decent size because it will transition to bloom far too soon for you to bring more than a snack-sized bud to harvest a few weeks later. This can be a fun botanical experiment or a novelty ganja gift for a friend, but never a proper cannabis plant.

Timing is everything when you grow autoflowering cannabis. Just like photoperiod cannabis, you can expect the same four stages of growth as follows: germination, seedling, vegetative, and flowering. However, autos will race from seed to harvest and fly through each stage like a photoperiod plant in fast forward. On average, contemporary autoflowering strains have a 60- to 90-day lifecycle.

To Transplant or Not to Transplant

The paper-towel method should deliver tap roots from split seeds in just two days. Many commentators will suggest you stick the germinated seeds directly into dirt or just whack them in straight out of the pack and into soil, but that’s not the best way to get your autos off to a strong start. Instead, carefully insert germinated seeds in some peat or root riot cubes for the duration of the seedling stage.

Shortly thereafter — sometime between day seven to 10, when you can see healthy root development — is the moment you should make your first and final transplant into a bigger pot. A propagator is an essential piece of equipment to keep the relative humidity (RH) high and avoid sluggish seedling growth.

Time is always the key factor and there is not a day to waste. As soon as your autoflowering cannabis seeds germinate, the clock is counting down to harvest day. It’s so important to make sure you nurture your seedlings because there really is no time for them to recover from a botched transplant. Early delays will come back to haunt you when it’s time to harvest.

Container Size for Autoflowering Cannabis

The optimal size container for autoflowering plants is the 2.5- to 6.5-gallon range, so a 4-gallon smart pot is perfect whether you plan to grow your weed indoors or outdoors. Smaller, more indica-dominant modern autoflowering hybrids are pretty squat, branchy, and rarely exceed 23 inches in height, although some have a stick of bud-growth pattern and are best suited to a screen of green (SOG) or high-density farming. Bigger, more sativa influenced super autos can stretch taller and peak close to five feet tall, of course, there are plenty of pint-sized sativa-dominant autos available these days too. The majority of indica-sativa autoflowering hybrids will max out between 23 inches to four feet tall. Oversized containers are not really required. Remember, these babies are not just more compact than traditional photoperiod cannabis; they will accelerate through the stages of their lifecycle.


Can you Prune and Train Autoflowering Strains?

The short answer is yes. Modern autoflowering cannabis has evolved so far beyond the disappointing Lowryders of the past, it’s like trying to compare Homo sapiens with a lemur. You absolutely can let your green fingers work their magic on most contemporary autoflowering cannabis strains. The one possible exception being intensive combinations of multiple pruning and training techniques like those involved in mainlining.

However, there is nothing to stop even a beginner grower dabbling with some low-stress training and/or topping to increase yields. And grand masters can certainly fill out an SOG even faster with the right autoflowering genetics.

What Triggers Blooming in Autoflowering Strains?

In general, modern autoflowering strains will flower on or before they hit day 30. That’s 30 days post germination. But this is not always the case. For indoors under the preferred 20/4 or 18/6 light cycles, this should prove to be accurate. In contrast, outdoor growers are likely to experience greater variance. Spring conditions tend to prolong vegetative growth to closer to day 40. With just 13 hours of daylight, progress is a little slower and overall plant size reduced. Summertime crops are almost always bigger and better as plants benefit from more intense sunlight for 16-18 hours per day. And even autumn auto crops can be impressive, although not quite as bulky as the summer stash.

Autoflowering cannabis is genetically pre-programmed as to when it flowers. Pot size seems to have no impact. Reduced hours of daylight don’t trigger them like 12/12 does for photoperiods. In fact, with as little as six hours of sunlight per day or continuous 24 artificial illumination, an auto can survive and progress through each growth stage and will not transition to bloom until its genetics activate flowering.

Why You Should Grow Autoflowering Cannabis

Autoflowering cannabis is awesome. High THC, CBD-rich, and diverse terpene profile varieties can all be found in contemporary autoflowering cannabis seed collections.

Outstanding feminized autoflowering cannabis seeds are already delighting growers with high-grade homegrown. It’s about time you grew the cannabis of the future and discovered the potential of autoflowering cannabis.


Source: Maximum Yield, "Maximizing Autoflowering Cannabis Growth, March 2, 2020,


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