Its depends on what strain but a week-12 days usually, I think as the planet gets more an more messed up people who grow outdoors will notice strange things like this happening way out season, its happening on both sides of the pond and if you ask me theres more of this on the way. You can force them back into Vegging by doing what your doing but 100w is a little on the small side, just hope for the weather to settle fingers crossed for you.