I know several greenhouse growers that use the light cycle to their advantage and harvest twice a year
yea it can be a little complicated to keep track of, but for the best buds it's worth it. Cannabis is very resilent and can handle a lot of things like I have a 2 footer out in the area I plan to grow this year right now even though it's like a month too early (maybe a few weeks dunno need to look it up) but I did it too give me an idea how I will need to prep the soil, from the way the plant is growing I see that I will need to adjust PH of the soil for more alkalinity and the compost I need to add for organic feeding should be a high nitrogen mix (spent coffee grounds is one of my favorites for nitrogen production although I will likely add bat poo this year) if I let it live it will continue trying to flower then reveg and I will get something off it (if nature doesn't reclaim it) but the potency will not be quite what it could have been due to the additional plant stresses.
That and depending on your weather patterns will vary according to when ya want to put it out, like in my area for the first few months of planting season and the last 2 months of harvest season (octoberish) RAIN RAIN RAIN so for early crops I try to lollipop and plant them deep so the roots don't get rot. This trick also works amazing for when summer comes because the deep planted root network will reach out and grab water so no worries if you can't tend the crop
Oh and early crops depending on their genetic makeup can become MONSTERS when I was a youngin' I grew outdoors and I remember my first crop... I planted in early april I believe it was a full sativa strain (never got to harvest it got too cold and wet before it was done and got mold sativa's take a longer time to flower than indicas) and that little seedling grew to be nearly 7 feet by end of september right before it got mold.
Growing outdoors is easy stuff in my humble opinion although due the fact I do not feel safe tending my outdoor crops anymore leaving behind possible footprints and doing my best to take a different route each time to not make a trail and all that it just gets complicated to make the real potent cannabis outdoors. So my personal technique for outdoor crops is they are for processing, butter, oil, hash brick and salves are what I do with my outdoor harvests. That and since nature isn't anywhere near sterile since 90% of what I grow goes to other medical patients I prefer pasteurize the medication in some way so processing is the best option.
And for the other medical providers whom have an issue with my previous statement let me break it down real quick, growing indoors you are essentially creating a incubation area for all kinds of microbes spores all kinds of crap to grow and prosper but unless you are running a medical warehouse (like some of the california providers) hopefully your grow room is small enough to keep sterile. (for example e. coli for example has been found in samples of patients medications, it started from a tiny spore maybe off of a pet turtle and that spore or in e. coli's case microbe floated on the air or on someones skin or clothes into the grow room. As I said the grow room is a perfect incubation area so it had a perfect place to live prosper and multiply for those of ya who are getting bored hold on this comes to a point) as I said hopefully your grow area is small enough to keep sterile and of course you follow sterile procedures, gloves face mask and "booties" or in some growers case instead of just booties a whole onezie thing so they can take off their outdoor clothes to ensure no pests follow them in. But back to the main point outdoors those microbes and crap are everywhere, but nature doesn't always provide incubation areas for those spores microbes and what not, as an example buy some bread take 2 pieces from the same loaf put one in a location within your home and another out back or somewhere outside and compare how long the bread takes too mold due to the lack of incubation area the bread outside will take twice as long to mold, some growers use this defense as a reason NOT to pasteurize outdoor grow medications and while I understand their logic I deal with a number of patients many of which I don't know from adam and we don't have much time to discusss their needs allergy's and what not so for example 2/3rds of the patients I have dealt with since I turned 21 a few years ago have one thing in common, mold allergy's some of them severely allergic. If I did not pasteurize their medications even though I knew I didn't have full control of the grow area (indoors crops that get processed I don't do any extra pasteurization as I already know it's clean) and their was even a few mold spores that in turn were ingested by the patient either vaporized or ingested or even smoked could mean an allergic reaction, I have been doing this since before I should have and I never have given any patient suspect medications if I ever sent someone to the hospital for something I could have avoided it will be in the back of my mind for the rest of my days.
Well long tangent sorry if the info bored anyone just trying to help everyone grow the best medicine they can!