Some growers believe it's better to give marijuana plants 18 hours of light a day max, with a 6 hour dark period during the vegetative stage.
Many Indica hybrids (such as AK-48 and Northern Lights) naturally have very short flowering periods of only 7-9 weeks, which is a shorter flowering time than most other strains.
3.) Give Plants 24 Hours of Light per Day During the Vegetative Stage
Simply put: fixing a problem quickly equates to shorter time to harvest.
So for example, Northern Lights has a flowering stage length of about 8 weeks. If you flowered a Northern Lights strain plant from seed, your buds would be ready to harvest in about 11-12 weeks.
2.) Choose A Quick-Finishing Strain of Marijuana
In my experience, top-fed Deep Water Culture hydroponics (also called 'bubbleponics') has given me the quickest growth of any hydroponics system I've tried.
The strain of marijuana you grow has the largest impact on how long it will take. If you choose a fast-growing strain, you can speed up the process considerably.
That is unavoidable.
If you provide your plants the perfect conditions, they will grow faster, and produce buds faster as well. This means you need to give them the right type of lighting (quantum board LED lights from HLG are perfect; if you are on more of a budget, check out Spider Farmer), a good growing medium, the right amount of water and nutrients, and the right temperature and humidity.
The amount of time it takes to grow cannabis can vary greatly, but there are things you can do to speed it up. Some, like shortening the vegging time, will have negative effects on yield, so you should always weigh the options carefully.
Minimize Vegging Time
Vegging in one room and flowering in another allows you to harvest twice as often. While one set of plants is in the flowering stage moving toward harvest, you can have the next group vegging in a separate area. Then you can move them to flowering as soon as the group currently flowering has been harvested.
Read Why Does My Weed Smell Like Hay? for more on what can happen if you dry your buds too quickly. I’m sure you can already guess one issue from the title of that article.
But that is just an average. The time it takes for weed to grow varies greatly. As mentioned, it depends on a number of factors and can range from 8 weeks to well over half a year.
How Long Does It Take For Weed To Grow?
Outdoors, the shortening days tell the plants to begin flowering. Indoors, you shorten the amount of time you leave the lights on, going from 18 to 24 hours of daylight down to 12. Or, if you are using an unusual lighting schedule for vegging, like 6 hours on and 2 hours off, going from that to 12/12.
Let’s break the time it takes cannabis to grow down into the different stages, so you can get a better idea of how long each stage takes.