How much light can a budding plant take before it is forced to re-vege?
Each variety has a critical period of darkness regarding flowering. The amount of darkness varies by variety. If the plant receives more uninterrupted darkness, it flowers. If it receives less, it remains growing vegetatively or eventually reverts to flowering.
With the coming of fall the plant in your window has responded to the longer dark period by flowering. If you place it outdoors it will continue to receive a longer and longer dark period so it will continue flowering.
Most varieties that are available commercially require fewer than 12 hours of darkness to flower. If the plants start to flower outdoors before Sept 22, when the dark period reaches 12 hours, then their critical period is fewer than 12 hours. To figure the amount of darkness that a variety growing outdoors requires, notice when the first flowers appear. The plant experienced its critical period about 10 days before. Look up the sunrise-sunset times at your latitude. The time between sunset and dawn represents the amount of dark time the plant needs each day in order to flower.
If the plant only needed 10.5 hours of darkness to flower outdoors, it will also flower indoors under that regimen.
Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA. You can also email Ed at [email protected], and send queries via his websites at www.ask-ed.net. All featured questions will be rewarded with a copy of Ed’s new book, Best of Ask Ed: Your Marijuana Questions Answered. Sorry, Ed cannot send personal replies to your questions.