When does a sativa strain flower in british columbia?

Are you asking when, seasonally, a plant would flower? All anyone could really give you is a loose window. Some variables come into play.

 

I live at over 55 degrees North on the coast of Alaska on an island. We have always had problems with photo plants finishing before the fall cold and rains move in. The answer to growing outdoors in Northern latitudes is auto flowering plants.

I've been procrastinating about doing an outdoor autoflower crop here for 2 years now and still haven't but my friends this far North that try photos outside never finish them before they get ruined by weather. Autos finish in a 60-90 day time period and if you get them in the ground in late May you have plenty of time for a nice harvest before the fall rains and cold.

This is the most reputable auto seed seller I know of. Rave reviews from what I've heard to the point where some auto growers grow only their seeds.
Welcome to Mephisto Genetics US Store. Home of the Autoflower Enthusiasts! | Mephisto Genetics USA

 

The only other solution is building a black tent for your plant to block out light and tenting it 12 hours a day manually to induce flowering early. That's the way old school Alaskan Thunderfuck growers did it.

 

Yup, like tbone said autoflowering strains are your best bet. Sativa’s definitely won’t finish in time.


My new grow

 

Just use the tent at dusk through overnight and in the morning to assure they get full 12 darkness. They will flower if you do that.