Outdoor planting dates and starting seeds indoors....

Cannabis loves to flower at the slightest mismatch in lighting when setting out early started plants. You can error and gain hours of day but any shortening of the day they are used to will flower them sure as anything.

And no you can't wean them off a high light cycle fast enough to be of any use so forget that idea.

Cannabis triggers flower at 14.5. At 15 they veg and at 14 they flower. So we need to run as close to 14.5 as we can. 15 - 9 is best but 16.- 8 can be used if your seeing flowering at 15-9. Start them from seed on a low hour cycle and don't change it.

Don't be in any rush putting them out. We want that peak 60 days of summer hours (June-July). Late May or the 1st of June is fine and you'll have monster plants.

Your other Choice.
Screw all that shit and leave a light on over them 24-0 from the day they sprout until Aug 1st. Kill the light that day and they'll flower and be ready to harvest about Oct 15th. This is how I've run for the last 10 years.

BNW

 

My repeated fails at getting a good time match did teach me more Cannabis and flowering then a dozen successful attempts ever would have and in a round about way led to me exploring and ultimately figuring out the 4 harvest outside per year I do now. Never freezes here so I can keep growing cannabis outside year round.

BNW

 

June 1st is my setout and the plants are usually about 3 feet tall.

Mid Sept last summers grow.
6-8-10 and one over 15 feet tall.

BNW

 

I'm lucky to live where it never freezes so I can keep growing Cannabis outside all year round. 10 years ago I figured out I could get 4 harvests per year and I have set dates things get done on to insure the next group of plants does the right thing on the right day.

Aug 1st = Take Clones / Plant seeds
Oct 15th = Harvest, Set out veg plants, take clones from same
Jan 1st = Same
March 15th = Same
June 1st = Harvest, Set out veg plants
(June-July) = Summer veg time

I have 4 foot veg plants in the ground I just turned the lights off over. They'll be ready to harvest Mar 15th and the clones in veg now under a mix of Sun and Lights will go in the same holes as fast as the plants get harvested and the sites are emptied. I'll take clones off that set of Veg plants Mar 15th and that set of clones will be the June 1st setout for Summer plants.

BNW

 

If your spring temps are generally mild you can start a plant or two now. Veg until mid March. Flip it / Set out and harvest it June 1st. Even if you have to baby it in March and April by bringing it inside on cold nights it is more then possible.

5 gallon Bucket on a 4 caster moving dolly and roll it inside the not so cold garage on predicted 35 deg and colder nights.

BNW

 

BNW gave you solid advice. I would add it depends on what part of the MT time zone you are actually in. Northern or southern will make a huge difference. I'm in NY state. If I start seeds on April 20th. I will have a 6 week old plant ready to start my 1 week hardening off cycle to go outdoors on June 1rst. A six week old healthy plant is like a teenager. It will take off quickly once planted outdoors and you will match the potential of the strain you are growing. Starting a plant too early can lead to a root bound plant that will not do as well as one that is timed properly. Don't forget your IPM.