Mainly I am posting this thread just to see if we can concentrate some knowledge on the subject, there are many threads here with info on the subject, but no regular running discussions.
The subject I am referring to as forcing is also known as "bagging", "capping", "black-out", and a variety of other terms. Basically it is the technique of manipulating the natural photo-period in order to bloom and finish strains out of their normal season. This is accomplished by shortening the day to 12 hours of light by blocking out light, allowing blooming in mid summer or spring.
There are many situations that forcing could help with, I use forcing sometimes to supplement my stash. If my regular Autumn harvest was too small to last through the next harvest, I can start seeds in March, veg indoors one month, move them into a GH by April, force them under 12/12 starting in early May, and have a harvest by July 4th.
I can see other advantages, especially for those with bad outdoor climates, ones that get too cold, and ones that are too wet during the blooming season.
By adjusting the photo-period, a grower could force a plant that finishes in October normally to finish a month or two earlier when cold and mold are not such a problem.
Another grower may want to try a strain that finishes in November or December naturally, by adjusting the photo-period many northern growers could finish tropical sativas before cold prevents it, inside the GH or not.
I once read a story about a college student in the San Fransisco bay area. He converted a old chicken coop into a greenhouse, at the beginning of summer break he'd fill the greenhouse with plants, and in July he'd force them. By the time classes started again he was done and harvested and ready to devote his time to school. And his harvest was done before rippers became a problem.
Another person who may be helped by forcing is breeders, especially breeders who would like to work with potent tropical sativas for the purpose of breeding with shorter season Indicas(perhaps with the intention of adding potency to local outdoor plants).
In some climates a breeder may be able to do 4 back-crosses in a year.
In climates where lots of sunshine is available year round, but the climate is cold in winter, double paned heated greenhouses and manipulation of the photo-period may allow near year round harvests. I have observed many high desert locations in the western USA where this could be done.
Anyways, here is a list of threads I've found with at least some info on forcing:
Where's the Light Deprivation Experts at?
worries for light deprivation
do you think there is a market for a stealthy auto darkining greenhouse?
black boxing info needed
Blackhouse for All-Summer Flowering!
Shed force flowerer using a garage door opener?
Nice looking greenhouse design with flower forcing cover
Anyone else here into this? Have something to share? I think this is a under explored subject.