Cannabis Light Schedules: Vegetative Stage vs Flowering Stage-2019 Updated

If you’re growing a cannabis plant grown from a random seed (“bagseed”), unless you somehow have an auto-flowering seed, you will need to understand about cannabis life stages and how they are affected by light periods.

If you don’t understand light periods, your plant may never start making buds! The light schedule experienced by your plant will actually change its life stage.

Vegetative Stage

Being able to manipulate a plant’s light schedule makes it possible to achieve higher yields when it comes time to harvest. When plants are in the vegetative stage, the more light they receive the larger they will grow.

Even when growing outdoors, many growers will start their plants inside to ensure they can grow as large as possible. When in veg, plants should be kept under grow lights for a minimum of 18 hours (commonly known as 18/6). Some growers will keep plants under 24 hours of light during this time (known as 24/0) to allow their plants to grow as big as possible.

Marijuana plants don’t begin to flower until they begin to receive 12 hours of uninterrupted darkness. Until then, they’ll continue to stay in the vegetative stage. You can essentially keep your plants in veg forever as long as they’re receiving 13 hours or more of light each day.

Flowering State

Indoors most growers put their plants on a 12–12 schedule to initiate flowering. Outdoors the plant will naturally start budding in late summer when nights are growing longer and longer as winter approaches. Just make sure plants aren’t exposed to light during their dark period!

What is 12–12 Lighting?

The indoor grower will need to artificially induce flowering/budding in plants by changing the cannabis grow light schedule so the plant receives only 12 hours of light a day, and 12 hours of uninterrupted darkness.

Once the plant is changed over to the flowering (12/12) light schedule, there is generally another 6 weeks-5 months (average 2.5 months) before the plant’s buds are ready for harvest.

Once the flowering stage of the marijuana plant gets going, this is when it will start to bud and grow flowers. In other words, this is when those sticky icky buds start growing. During this stage, the plant will not grow quite as much in height anymore as during the vegetative state. Yes, it will still grow, but not nearly as much as during the vegetative state.

However, as the buds begin to form and grow, you will notice your marijuana plant filling out and getting wider, which is because of the weight and growth of the actual buds, what you are going to dry and smoke.

Most of the THC content or potency of your weed will be developed during the few final weeks of the flowering stage. This is also a very important stage, because how you treat your plant here will go a long way in determining the size, flavor, and potency of the weed itself.

Successful growers do these two things:

Use automated timers during the vegetative stage. This ensures consistency and precision when managing the light cycle.

Maintain at least 14 hours of hydroponic grow lights during the vegetative stage. Marijuana doesn’t need darkness until they are ready to flower.

Believe it or not, you can give your plants up to 24hours of light daily during the vegetative stage, and plenty of growers do.