Growing Cannabis Inside Without Lights

Stephen Andrews
30 Oct 2023

When people think of cultivating cannabis indoors they often imagine a fully-packed grow room with decent lights, fans and everything. However, growing is also possible without all of that. One way to go is place your cannabis pots by a window with good exposure to sunlight. It’s called window farming. But whether you ask if cannabis can succeed with absolutely no light at all, that’s like asking if a human can live without oxygen.

Growing cannabis can be as inventive as anything else. You can always improvise if you want to keep the whole operation low profile, or if you don’t have the place or enough resources to set up a fully-functional grow room. 

So, you can certainly grow cannabis indoors without artificial lights, but the plants would still demand direct access to natural light for at least six hours a day. That means the best chance for the plant to succeed is to be positioned in a place where there is access to sunlight, and you can additionally use CFLs which are cheaper. 

You see where this is going. Whether you wonder if you can grow marijuana in complete darkness, quit reading now. 

Cannabis after all is a photosensitive plant, and light is one of the three key resources alongside water and carbon dioxide so that it can perform its natural processes such as photosynthesis. Without light, like many other plants, cannabis won’t succeed. 

How to Grow Weed Indoors Without Artificial Lights?

Your best bet is to maximize exposure to sunlight. One way this can work is to place the plants on a windowsill and watch how they progress.

It’s important to note that in this setting, cannabis still won’t be in an ideal growing environment. In the absence of the best conditions, plants lose in ways that they do not grow as much as they can, nor they yield the maximum quantity of weed that’s expected for that strain. But there are things you can do to improve the outcome. 

Grow in Summer

Window farming is a good exercise to try among those who are not seriously interested in growing weed all the time, or who just want to test if that’s the kind of activity for them. If you are relying on light coming from the window, you will definitely benefit if you grow during the summer when there are more sunny hours. You need the most sun you can use, and autumn and winter months are no use of that. 

The window of time you can use is between April and August. If you start germinating and planting before the end of April or after August, there’s a great chance that your growing attempt will be a failure.

Remember that, during vegetation, marijuana plants need at least 14 hours of light per day, of which it’s good that around 5-6 hours are direct exposure. Anything short of that might result in a stunted growth

Pick a Strain that Works

The beautiful thing about having so many different cannabis cultivars is that there’s flexibility for growers on how they can use them depending on the growing conditions. Picking the right variety of cannabis for indoors growing without lights can make a huge difference with the end result. 

One option is to take auto-flowers as they are not photoperiod and do not depend on the change of seasons. Autoflowering cannabis is day-neutral, meaning it does not require a specific light/dark cycle in order to grow. It will automatically switch from vegetation into flowering based on age. Autoflower seeds also grow into relatively small plants compared to feminized seeds, therefore they can fit in a position such as the windowsill. A tall-growing sativa would definitely not fit there. 

If you live in a really warm area you can still try and opt for a photoperiod sativa plant, which can succeed in summer. If it’s colder, you can try out with indicas. But photoperiod will normally require more effort to grow a stable plant in this kind of setting compared to autoflower. 

Find a Good Spot 

Don’t place the plant by just any window. Start your grow operation around the one window in your home where there’s the most sun. The bigger the window the better as this means more light exposure for the plant. You should also rotate the pots occasionally so that each side of the plant gets direct access to light. 

For better results, opt for windows that are facing south, but also south-west or south-east will do. That will maximize the exposure to sunlight. Whatever you do, just avoid north-facing windows as that almost certainly sounds like a promise for a poor outcome. It’s also preferable that there are no big obstructions in the way of light, for example a very tall tree. 

Regulate Watering and Room Temperature

Marijuana plants that are not cultivated under artificial lights will require less water than usual, because they will have less evaporation. Therefore, avoiding overwatering is also crucial. You can measure the pots’ weight when they are full and when they are dry to have something as comparison and guidance when to water. 

It’s important to sustain a good indoor temperature. Too humid and it might attract fungus or other pathogens. Keeping around 68 degrees Fahrenheit is the recommended temperature for indoor grow operations. Anything below that can stress the plant or attract unwanted visitors. 

When the cannabis plant is in vegetation, the maximum room temperature can go up to around 82 degrees. During flowering, it should be no more than 78 degrees. 


Yes, you can grow cannabis indoors without lights. But don’t expect to get the best buds you can from a plant. For the outcome to be better, stick to a plan where you use autoflowers which are still exposed to the maximum light you can get from some of the windows in your home. Alternatively, look for other places where you can position your plants, such as a balcony or a greenhouse. 

Also read on Soft Secrets:

10 Mistakes To Avoid When Growing Indoors

8 Ways To Get The Biggest Yields Indoors

How Do You Heal Your Dying Cannabis Plant?

Stephen Andrews