Growing weed indoors can be fun and rewarding. There nothing like growing your own herb and reaping the rewards at harvest time. And when you grow indoors, you get as many harvests as you want! That is not possible when growing outdoors.

Getting many harvests per year means you can actually blitz through runs, making mistakes and learning as you go. Outdoors, you get fewer opportunities to “practice” your craft. But if you become an indoor grower, you get a lot more runs under your belt, and your skills build faster than if you only had one chance a year to practice this craft.

However, when you do grow indoors, you must control the “sun” in order to coach your plants through the various stages of growth.

In this article, we will explain how to manipulate the light cycles necessary to grow top shelf flower in the privacy of your own home.

How much light a weed plant needs depends on what “stage” the plant is in

There are two stages of growth during the life cycle of a cannabis plant. The first stage is called the Vegetative Stage, and the second stage is the Flowering period.

Each of these two stages requires a different amount of light.

The vegetative stage requires more light than darkness in a 24 hour period.

The flowering stage requires an equal amount or more of darkness than light in a 24-hour period.

Now, think about how these stages would naturally occur outside. In the summer time, the days get really long, and at the peak of summer, the sun doesn’t go down until 9pm at night. If you were growing cannabis plants outside during this time, your plants would be going through the vegetative stage.

Then in late August or early September, the days would start getting shorter and shorter. This additional darkness would eventually trigger your plants to start flowering.

So how do we achieve these conditions when growing indoors? By using the tried and true light cycles described below.

Weed light cycles for growing indoors

There are several common light cycles that indoor growers use.

For the vegetative stage, many growers (including us at Smokey Okies) use the 18/6 light cycle. We use light timers to keep the lights on for 18 hours a day, and then shut off. After six hours, the lights turn back on.

When we are ready to flower the plants, we use the 12/12 light cycle. We set our timers to stay on for 12 hours, and then shut off for 12 hours.

These are the most common light cycles, however you can experiment with other cycles, such as 20 hours on, 4 hours off for a faster veg.

You could even leave the lights on 24 hours per day until you were ready to start flowering. Though, we prefer to allow plants to rest, and therefore we use the 18/6 light cycle when vegging our plants.

Light cycle for seedlings

After you plant a seed, and it has sprouted above the dirt, we call that tiny plant a seedling. Seedlings are very delicate. Too much light intensity, too much water, too much of anything can stunt or kill a seedling.

Seedlings are technically plants in the vegetative stage, although, they will not flower even if you subject them to a flowering light cycle with plenty of darkness.

We suggest using the 18/6 veg light cycle for your seedlings, but keep the intensity very low. You don’t even need direct light, and you can set clones and seedlings aside so they are hit indirectly. That is fine for a couple weeks until they are sturdier and ready to be transplanted into a larger container for a full veg cycle.

More questions?

Obviously, there is more to cover on this subject, and we are here to help. So check out these articles on related topics:

Also, you might want to check out our Week-by-Week guides:


Join our mailing list to receive the latest news and updates from our team.

You have Successfully Subscribed!