By Max Sargent

When you think of cannabis cultivation, you may imagine a foil-lined room with large, powerful lights hanging from the ceiling. However, this sort of setup may not tally with the more quaint notions of cannabis cultivation you have for yourself.

Maybe you just want to put a plant on the windowsill without dedicating a whole room to it, or perhaps you can’t afford a good set of artificial lights.

The good news is, you can do it. But your plants will still need light. Light, along with carbon dioxide and water, is crucial for photosynthesis—the process whereby plants create carbohydrates for themselves. So you can’t grow weed without light, but you can without artificial light!

Can You Grow Cannabis Indoors Without Lights?

Despite all the hype around creating the perfect grow space, it is possible to cultivate happy and productive cannabis plants indoors without grow lights. In fact, it’s possible to put a couple of plants on a windowsill and watch them thrive.

That being said, high-tech growing spaces are no fad. Providing the optimal environment for your plants comes with huge benefits, and likewise, growing outside of the optimal environment will reduce the size and quality of your yield. Still, a low-tech indoor grow can yield respectable results, especially for the casual grower or the grower on a budget.

But if you’re wondering if a weed plant can stay alive without light, the answer is no. If you grow without artificial lights, you’ll need a good amount of natural light to compensate.


First, let’s look at the benefits of growing cannabis indoors without lights. For many looking to grow weed, especially those who haven’t tried it before, these benefits will be enough to make this option very appealing.


First and foremost, it’s cheap.

High-quality lights, whether you go for LEDs or HIDs, are expensive—as is power consumption, rigging equipment, and so on. The sun coming through your window, on the other hand, is free!

In the vast majority of cases, those growing without lights will also be growing without a tent, which makes the endeavour even cheaper. Tents, exhaust systems, and so on all add up to at least a few hundred pounds—and often much more.

Using an available room and natural sunlight reduces the cost of growing weed to purchasing the following:

  • Seeds
  • Pots
  • Soil
  • Fertiliser
  • Water
How to Grow Weed Indoors Without Lights
Not using lights or a tent can be very liberating. Sure, these pieces of equipment get the most out of your grow, but there’s no denying that fitting out a room (or part of a room) with all the equipment to grow a crop of weed can take up a lot of space, make noise, and emit light. This makes this kind of growing operation quite the commitment. A couple of weed plants on a windowsill, however, are much less of an intrusion into a person’s life. Apart from their smell (and sometimes considerable size), they’re no different from any other kind of house plant when grown in this way.

When you grow more simply, you’ll find that much less of your time is taken up by tending to your plants, adjusting lights, and so on.

Which all boils down to simplicity!

Growing cannabis without lights is a much simpler endeavour compared to growing with lights. Less equipment, less power usage, and less dedication all make growing indoors using natural light much, much simpler.


As with all things, each positive has a negative. And while it’s true that growing weed without artificial light is simple and easy, it’s also true that you have to expect some downsides too. 


Unless you have a window that faces in the perfect direction (south, south-west or south-east) and is very large and gets uninterrupted light, your plants will probably stretch.

Cannabis plants stretch when they are unsatisfied with the amount of light they are getting. In nature, this is an attempt to rise above an obstructive canopy and find direct sunlight. Indoors, you’ll probably just find them long, spindly, and pressed up against the glass. If plants stretch too much, they can autumn over. And even if they only stretch a little, they can end up being pretty tall, meaning they require more space.

You Need Windows

Realistically, to get a satisfying haul, you’re going to need south, south-west or south-east-facing windows, and they’ll need to be big and unobstructed. For some, this won’t be a problem. For others, it could be game over.

Below, we’ll go over exactly what you need in terms of windows to grow cannabis indoors without lights. But for now, just know that a small, north-facing window probably won’t cut it!

Smaller Yields
The numbers seed banks advertise can be difficult to achieve even in optimal conditions. If you’re a novice growing on a windowsill, don’t expect your plants to yield 750g/m²—or anything close to that! Depending on your strain and setup, expect between one (28g) and a few ounces per plant when growing indoors using natural light.

Tents and exhaust systems go some way to trap and remove odour. If you’re growing on a windowsill, there’s little you can do to stop your house from smelling like weed, beyond opening the window.

If this bothers you, there are strains that are less stinky. Plus, the reduced yield of plants grown on windowsills means that they won’t emit the extreme stench of plants grown beneath lights.

Stealth Issues

Depending on where your windows face, your neighbours might be able to see what’s growing there.

If this is the case, seriously consider how they will react if they spot your cannabis plants. It’s not worth a visit from the police!


When you grow indoors, you’ll have to move your plants in a number of situations.

  • As the light is coming from one angle, your plants will lean toward it. This means you’ll have to turn them fairly regularly to keep them upright.
  • Photoperiod cannabis plants need periods of absolute darkness. Unless you can draw the curtains and commit to complete darkness, photoperiod plants will need to moved into dark spaces (such as cupboards) every day.
  • You might also choose to chase the light. If you live somewhere that has both south-east and south-west-facing windows, you might start your plants in the former at the beginning of the day, and move them to the latter after noon. This will allow them to receive as much light as possible per day.

How to Grow Weed Plants Naturally Indoors

With the pros and cons out of the way, let’s find out how to grow weed plants indoors with natural light.

  • Grow in the Summer

You need all the help you can get! The dim days of winter won’t cut it if you’re growing using natural light. The days between the spring and autumn equinox offer the light levels necessary to grow weed.

Plants need at least six hours of direct sunlight a day, and more indirect. So a gloomy day with six hours of light total will leave your plants stunted and exhausted, if they live at all.

  • Choose a Suitable Strain

Depending on the environment, certain strains will be more successful than others.

As a general rule, sativas love real heat. So if your windowsill bakes in the summer months, these strains will thrive. If it’s cool, or you use air-conditioning, consider indicas, which tend to prefer cooler environments. Picking the right cultivar will make a big difference regarding the overall success of your grow.

  • Find a Big Window

The larger the window, the better, as you want to maximise light exposure.

Some people won’t have much choice when it comes to choosing the best window, but whatever your options, know that bigger is better!

  • Direct Sunlight Is Perfect

In the same vein, the more direct light a window gets, the better. If there’s a building that obscures the sun, then try to choose a window that gets more direct light. Direct sunlight is what plants thrive on; they’ll be grateful for it!

  • South-Facing Windows Are Best

Ideally, your windows will have a south-facing orientation. It doesn’t need to be exact. South-west and south-east-facing windows are (almost) equally ideal candidates in the summer months, as they get the strongest and most direct light.

Otherwise, east and west-facing windows can also work. They won’t get as much light as south-facing ones, but it should still be okay.

Generally, north-facing windows make poor growing spaces, as they get very little direct light.

How to Grow Weed Indoors Without Lights
  • Higher Is Better

Windows higher up in the house will get more light, and are more likely to be free from obstruction.

If you have a choice, and it fits the criteria, higher windows make better growing spaces.

  • Open the Windows Sometimes

Opening the windows from time to time can help to replenish fresh air supplies and avoid stagnation. High humidity and stale air is a killer for cannabis grows, so getting some air exchange going can be really helpful. It also helps to stop the smell from building up too much.

  • Move Them From Window to Window

As mentioned, certain windows may be more suitable at certain times of day. If you have windows with various orientations, then try to move your plants around to follow the sun, even if it’s not every day.

  • Rotate the Plants

To keep plants growing upright, rotate them at least once a day. This stops them from leaning to one side in an attempt to find more light.

  • Water Minimally

Compared to growing under artificial lights, evaporation will be minimal when growing on a windowsill. Given that, it won’t be necessary to water your plants very often.

In fact, to avoid the growth of fungi and pathogens, you’ll want to water your plants just enough to support growth, and no more. To determine when to water, consider weighing your pots and substrate to see how saturated the medium is when dry versus hydrated.

  • Complement With CFL Lights

CFLs are on the cheaper end of the spectrum. Especially if you don’t have the perfect setup, supplementing with CFLs can get blue light to your plants, which is especially helpful when it comes to helping young plants establish strong root systems.

How to Grow Weed Indoors Without Lights

Is It Possible to Grow Weed Indoors Without a Tent?

Yes, in this article we’ve assumed that if you’re growing indoors without lights, then you’re probably not using a tent either. In fact, growing with a tent, but without lights, is probably going to be pretty challenging, as cannabis grow tents tend to be opaque.

If you grow without a tent, you have two options:

  • Transform a room into a grow room (and use artificial lights). This is a big commitment.
  • Just grow on a windowsill, which is what we’ve been focusing on here.

What to Expect When Growing Weed Indoors Without Lights

When growing marijuana without grow lamps indoors, your plants will lack the powerful, direct source of light they need to really optimise performance. As a result, plants may not end up as vibrant or abundant.

Based on our setup, plants will have light coming from one side, and it will vary in strength from day to day. As such, you’ll need to accept that the growth won’t be uniform. If you can deal with tall, wonky plants, you should be good!

Should I Grow Photoperiod or Autoflowering Cannabis Without Lights?

So far, we’ve mainly spoken about growing photoperiod cannabis strains, but you might be better off growing autoflowering plants indoors without lights. This is because this type of cannabis does not require a specific light/dark cycle in order to grow properly.

Therefore, you needn’t worry about a little light at night, and you don’t need to move your plants around so much.

Moreover, autoflowering plants tend to have much shorter life cycles compared to photoperiod plants. This means that you can grow them from May–August (autos often take just 2–3 months from seed to harvest) when the light is the strongest and the days are the longest.

Consider Alternatives

If you want to grow cannabis without artificial light, there are several alternatives available to you. Depending on your situation, one of the following options may suit your setup very well.


Cannabis thrives in greenhouses. Not only do these environments use natural light, but they help to maintain an artificially stable environment. Humidity and temperature are much more reliable in greenhouses compared to outdoors or on windowsills.

If you have a greenhouse that gets a good amount of sunlight, this is a prime growing environment.

How to Grow Weed Indoors Without Lights


Growing cannabis in the garden doesn’t mean you need large beds at your disposal. A patio, veranda, or terrace will all suffice too!

All you need is a space that gets a good amount of sunlight and offers a little discretion. To help keep your operation under wraps, consider growing companion plants to camouflage your weed plants.

How to Grow Weed Indoors Without Lights


Likewise, growing weed on a balcony is a great option. Just ensure that anyone who can see your balcony isn’t going to take issue with your cannabis grow-op. As with growing on a windowsill, situating plants on a south, south-east or south-west-facing balcony is best.

How to Grow Weed Indoors Without Lights


You could also grow in a courtgarden, if your neighbours are okay with it.

The main issue with courtgardens is that many can be pretty dim. So only grow in this type of space if it receives enough light to satisfy your greedy plants.

How to Grow Weed Indoors Without Lights

Growing Cannabis Without Artificial Lights: It’s Possible!

Growing cannabis indoors without lights is definitely possible. You might not get the gigantic, highly potent yields that you've been advertised, but you can still get satisfactory returns.

For beginner growers, or those who want to embark on an easygoing project, growing indoors on windowsill is a very valid option, and you don’t need to spend loads of money to get good results.

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