Cannabis & Hemp

The Case for Auto-Flowering Cannabis Seeds

Maybe you’ve written off auto-flowering seeds because you’ve heard that their yields are low, their phenotypes erratic and their highs less potent than those of their light-dependent sisters. Perhaps that was once true, but many breeders have been hard at work and they have produced what may sound like a miracle: high yielding, hard hitting and reliable auto-flowering seeds. It is time to give autos another chance.

What are Auto-Flowering Cannabis Seeds?

Auto-flowering seeds are not light dependent for flowering. They germinate, shoot up a few leaves and start setting flowers, without you fussing over their light schedules. How did that come about?

All auto-flowering seeds are the result of crossing Sativa and Indica plants with the Ruderalis strains. Ruderalis is a type of cannabis that evolved to thrive in the 18-24 hour daylight of summers in Northern Russia and the Northern parts of Eastern Europe. The summer days in that part of the world are long, sometimes endless, and by the time they start to shorten it is far too cold for a plant to produce flowers.

Normal cannabis plants require a switch from 24 hours of light to 12 in order to stimulate flowering, without which they just veg and veg. If wild Ruderalis followed this example, all its flowers would freeze before setting seed. So it switched to a time schedule, instead of a light schedule and produces flowers as early as three weeks after germinating.

What This Means for the Grow Room
  • Faster flowering and a shorter wait for the harvest
  • No need for separate vegging and flowering rooms
  • Plants of different ages can all be grown together
  • A constant supply of marijuana
The Downside of Auto-Flowering Seeds

The flaws in auto-flowering seeds come from their roadside origins. Pure Ruderalis is basically what is commonly called ditch weed. Hardy, compact, resilient and frankly, boring. The THC content of Ruderalis strains tends to be low, as well as the yields. The highs are weak and lack the psychedelic effects many users seek. These traits showed in the early autos; they were weaker than their sister strains and their yields were lower. The ease and speed of growing simply didn’t make up for their lack of oomph, or compensate for the small harvests.

Breeders Have Adjusted

Auto-flowering seeds have been around for a while now, and the breeders have become savvier. With intensive breeding, they are now growing auto seeds that produce anywhere from 500-1000g/m2.

Growing Auto Seeds

There are exceptions, but auto-flowering plants tend to be small and do well in high density grow systems like Sea of Green. They can also thrive in containers, but don’t like to be transplanted. Germinate them in their final pots (1-2 gallons works great).

One of the great advantages of auto seeds is the possibility of staggering your planting for a continuous crop in the same space. Each time you harvest a bud or remove a male (they tend to show 2-3 weeks after germinating) plant a new seed. No need to change the light; most autos do best on 18 hours of light a day from germination to harvest.

For the biggest yields, you do have to pay attention to feeding. It is important to switch from veg stage nutrients to flowering nutrients at about four weeks after germination or as soon as you see flowers starting to form.

Most autos perform beautifully outside, often giving higher yields than their indoor counterparts. The Ruderalis genetics lend these strains a degree of hardiness; they are often mold resistant and able to handle fluctuating temperatures and odd watering schedules better than their pure Indica and Sativa relatives.

You really should. The intense breeding programs of the last few years have produced some remarkable strains. These are autos that you would think were purely Indica/Sativa, if it weren’t for the fact that they grow faster and easier than any light dependent seeds.


Auto-flowering cannabis has finally made the transition from great idea to reality. It took a long time. The first auto seeds debuted around 2003. We are more than a decade and hundreds of plant generations in to auto breeding, and we are finally seeing high quality plants. Thanks to the tough, adaptable genetics of the wild Ruderalis, growers everywhere can now have the pleasure of growing fast, heavy yielding and sweet smoking cannabis without the hassle of having two grow rooms. So ditch the light schedules and give auto-flowering seeds a try.

Background information and the images for this article were provided by

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