Heavier auto sativas will go the distance ..... BUT in “ most “ auto strains the first 5 weeks makes or breaks them.
The whole reason is to set the “ base “ of the plants structure ( rootball / branching ) ... after stretch slows / stops it will not
make new leaf or branches. Sometimes the ruderalis ” Rudy gene “ doesn’t work well and plant has to be manually flipped.
Ruderalis was only introduced for speed and temperament but at times throws out some unexpected performance.
Many times grows are on point and the god damn auto grows 6” and begins flowering. If you seek SOG style plants , choose dwarfy / lowryder / bkr . Many autos can be topped too , but many get stressed.
One trick some auto growers do ( it works ) is to run the First stages under a long cycle ( 18/6 - 20/ 4 or 24/0 ) ...
Up to the transition point of sex and preflower
Then put under regular flowering like 12/12 to finish.
There is still no benefit from starting Flower early on autos ... but you can manipulate them AFTER budset.
For example ( above plant ) .....
Good Sativa lean ... You can defol the lower middle areas of blocked buds ( or tuck ) .
You can LST the hell out of it to further light penetration and bud growth.
That plant will definitely go longer than what ever 8-9 week breeder estimate.
And of course its parental lines ( genetics ) as some autos will run like reg. But I think that plant done with another under
18/6 or better would have shown noticeable differences because of cycle. Great looking plant btw.
I have one that NEVER flowered on its own so I had to treat it like a reg and flip that bitch. 1 gallon grow bag.
Im not even concerned about flower time since it did not go on its own. So this auto will get done when it gets done.
Under 18/6 or 20/4 ... I get much larger plant growth overall.