How to Grow Cannabis Indoors Without Grow Lights?

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Added 29 January 2023

Now, you want to try your hand at growing cannabis, but a setup can be expensive, especially grow lights. 

They can cost you hundreds of dollars, and premium ones with excellent PAR, PPFD, lumen, and whatnot can even thousands. 

But, what if you only want to experiment before going deep into it?

Is it worth investing so much on grow lights when you don't even know the basics?

And while you will find hundreds of articles asking the reader to choose the best grow lights on the market, you don’t need to do that as a new grower. What if we told you that you can grow cannabis without grow lights?

Sure, the plant will not be as big and the yield may be decent at best, but if you are a new grower, it is much more important to learn the process than aim for a pro-level yield, isn’t it? You must learn to walk before you fly!

This is why we have created this guide that will teach you how to grow cannabis in your home without grow lights. 

Before you proceed, know that this guide is about growing cannabis using the light filtered through large windows, so if you don't have that setup, stop right now, and search for something that will suit your purpose. This guide should read more like "how to grow cannabis on your windowsill". We hope this helps!

Can You Grow Cannabis Without Grow Lights?

You might be wondering if it’s possible to grow cannabis indoors without grow lights, but the question you should be asking is if your home is suitable for your cannabis plant. In most cases, it is. Your house probably has a perfectly safe environment for your cannabis to grow in.

A cannabis plant needs a few basic things to grow — warmth, air, light, and protection from the elements. Now, most of these basic things are already in your house, including clean air and warmth. But the biggest concern that comes when you want to grow cannabis indoors is the light. 

Cannabis, like other plants, likes to bask in a lot of light. 

So, although your house may be bright, the plant may not grow to its full potential. In regular conditions, your plant will experience a lack of light, stretching, or other light-related problems. 

This is where growers opt for artificial grow lights to mimic the sun’s natural light. But, if there are no grow lights, the plant will not get enough light. However, there are ways to circumnavigate this.

For example, due to lack of light, there won’t be enough evaporation, so you will have to compensate for it by watering your plant less to avoid mold or fungi buildup. 

As long as you keep these factors in mind — which we shall discuss further in the article — you can grow a happy cannabis plant that thrives. 

How Well Does an Indoor Cannabis Plant Grow Without Grow Lights?

How Well Does an Indoor Cannabis Plant Grow Without Grow Lights?

Let’s get one thing clear — your cannabis plant will not grow as well as it would with dedicated growing lights, but if you take the right steps, your plant can get surprisingly close to it. If you do it right, you won’t have to worry about your plant being less potent, dull, or producing a lower yield. 

But this will require some effort on your end. In the end, you will be surprised at how well your plant will grow and the yield it will produce without elaborate pieces of equipment. 

Advantages of Growing Cannabis Without Indoor Grow Lights

Advantages of Growing Cannabis Without Indoor Grow Lights

Growing cannabis without grow lights come with its benefits, which is why many growers opt to grow their cannabis plants this way in their homes. Here are some of the benefits.

1. It is Cheap 

Perhaps the biggest advantage of growing cannabis indoors without lights is cost savings — it is seriously cheap. High-quality lights, especially LEDs or HIDs can cost you a lot of money, sometimes thousands of dollars. 

And most light panels, except LEDs, consume a lot of energy over time — remember, you will be running the lights for at least 12 hours each day — and that can drastically drive up your energy bills. 

But sunlight is cheap. So, if you opt to not use grow lights, you can save a lot of money and use that for other things like pots, fertilizers, supplements, etc. for growing cannabis.

2. It is Simple 

The next benefit is simplicity. If you know anything about grow lights, you would also know that the subject is fairly complicated for new growers. With grow lights, you have to factor in the light’s intensity, spectrum, distance, and whatnot for the best performance.

All of this can make setting up grow lights a tedious process, and in some cases, even require you to pick a calculator and solve mathematical problems. Plus, grow lights require a lot of maintenance over time.

But when there are no grow lights, the entire process becomes much easier. Yes, you still have to put the effort into ensuring your plant gets adequate light without grow lights, but this is much simpler. 

3. It is a Good Starting Point

If you're a new grower growing cannabis for the first time, you wouldn’t want to spend a lot of time and money on expensive lights and other pieces of equipment — it can be quite binding. 

Not only is a proper grow setup intrusive in your personal space but it turns into a commitment. Growing cannabis without grow lights allows you to test the waters to see if you can do it before dedicating more effort and money to the hobby. 

Disadvantages of Growing Cannabis Without Indoor Grow Lights

Disadvantages of Growing Cannabis Without Indoor Grow Lights

Despite the benefits, growing cannabis without grow lights can have a few downsides that may make it unsuitable for you. Here are a few of the downsides.

1. Your Plant is Likely to Experience Stretching

Perhaps the biggest downside of growing cannabis without grow lights is that your plant will experience a light deficiency, which can lead to stretching. In an effort to get closer to the light source, your cannabis will keep growing taller and taller, which is what stretching is

Slight stretching is not a problem — it is expected in an indoor plant with no grow lights — but if it stretches too much, it can tip over or it may outgrow the space. Plus, if it is stretching so much, it shows that it is not getting light and the growth will be subpar as a result.

2. Your Plant will Produce a Smaller Yield

You can do everything to make sure your plant gets enough light but the truth is that it will never produce buds like it would with dedicated grow lights. So, realistically, expect your plant’s yield to be lower.

3. You Need Big Windows

While you won’t be using any grow lights, your indoor lights will not suffice for your plant. Instead, it will use the natural light that comes through the windows. This is why you need big windows so your plant can get the most amount of light for a longer duration. 

The big windows will also need to be unobstructed and preferably face south or southwest. More on this later.

4. Your Plant Won’t be Stealthy

In most parts of the world, growers have to keep their cannabis plants hidden due to legal reasons or the social dogma that still exists. If you live in such a region, you need to think twice before growing cannabis without indoor lights.

You will be placing the plant next to your window and your neighbors can spot your plant easily. Additionally, your plant will produce the signature cannabis smell, especially during bloom, which is difficult to conceal without carbon filters or scrubbers. 

5. You Need to Put in More Effort

Because you are using the natural light of the sun, you will have to move your plant around the house quite a bit to keep it under the light. Plus, you will have to regularly rotate your plant so it does not grow in one direction. 

And if you are growing photoperiod plants, you will also have to move them to a completely dark space during the light to mimic day and night. Here, even a slight light leak during the night can cause problems for your plant and potentially lead to hermaphroditism.

How to Give Your Cannabis Plant Enough Light Without Grow Lights?

How to Give Your Cannabis Plant Enough Light Without Grow Lights?

Addressing the elephant in the room, you need to ensure your plant gets enough light throughout the day in your room without any additional grow lights. For this, aim to give your plant as much direct sunlight as possible. Use these tips to do the same.

1. Choose a South-facing Direction

In most regions, the plant will get the most sunlight exposure in the southeast or southwest direction, followed by east and west. In the northern direction, your plant will get the least amount of light, making it unsuitable for your plant. 

So, you need to work with the seasons and place your plant near a south-facing window. Here, big windows or bay windows work best, and if possible, you should consider placing your plant on the windowsill or the balcony, too. 

2. Keep Rotating Your Plant 

Remember, you need to give your plant at least six hours of direct sunlight, and the more the merrier. So, you may also have to move your plant around during the day to keep it exposed to direct sunlight. 

Similarly, you should also keep rotating your plant. Otherwise, only one side of the plant will receive more light and your plant will grow in that direction. Rotating the plant will ensure all parts of the plant are more or less equally exposed to the sunlight, leading to a more even foliage growth. 

3. Germinate the Seeds During Spring Equinox

To ensure your plant gets enough light throughout the day, you should consider germinating the seeds during the spring equinox if you live in the northern hemisphere. This will ensure your plant gets enough light in the following season to help it grow big and bushy.

4. Consider Adding CFL Lights

You can also consider using CFL lights as they are quite affordable and don’t require a lot of thought in installing. CFL lights also produce a decent spectrum of blue light, which helps your plant establish a strong root network, so it is always a plus. Simply add a few CFL lights in your room, directly above the plant. 

How to Grow Cannabis Indoors Without Grow Lights?

How to Grow Cannabis Indoors Without Grow Lights?

With the basics out of the way, let’s start growing your cannabis plant indoors without grow lights. Follow these tips and tricks and you will grow a healthy plant that will produce a respectable yield. 

1. Choose the Right Strain

The first step in growing cannabis without grow lights is to choose the right strain, depending on your local environment and conditions. This is because some strains will grow better than others in your home.

Remember, you don’t have the luxury to fine-tune your indoor environment, so you need to pick a strain that suits your indoor climate — temperature, humidity, and seasons. 

Explore seed banks to see which strains they offer that might suit your needs. Reputable companies offer a ton of information and environmental requirements on their product pages, which will help you narrow down your search.

2. Consider Growing Autoflowering Cannabis

Cannabis comes in two varieties — photoperiod and autoflowering

Photoperiod cannabis plants rely on the duration of light when moving from the vegetative stage to the bloom. Generally, growers use an 18/6 light-to-dark cycle when their photoperiod plants are vegetating and when it’s time for bloom, the growers switch the light cycle to 12/12, which forces the plant to bloom.

On the other hand, autoflowering cannabis plants automatically start flowering within a few weeks. The advantage is that their growth cycle is shorter. But, they don’t rely on the light cycle at all, so they tend to grow smaller.

However, for a beginner grower with a basic setup, autoflowering cannabis strains are perfectly fine to grow. They give you a lot of margin of error and don’t have drastic light requirements, making them perfect for an indoor setup with no grow lights. 

3. Germinate the Seeds in the Summer

When growing indoors without grow lights, you want nature to be on your side. So, the winter months won’t be enough for your plant as the days tend to be shorter and dimmer. To get the best out of your plant, consider growing your plant in the summer when the sun is bright and the days are longer. 

Your plant will require at least six hours of direct light, and the more the better. So, grow your plant between the spring equinox and autumn equinox. 

Remember, this is just a general guideline, and, depending on your local region, these conditions might change. So, pick the time when the sun is the brightest in your region. 

4. Choose a Dark Pot with Drainage Holes

Next, you need to choose the right container for your cannabis plant. You need to ensure that the container you choose does not let any light through to the roots as it can lead to root problems. 

Additionally, the pot must contain enough drainage holes. Due to lack of light, the water will evaporate much slower, so if the water does not drain out quickly enough, it can pool up near the roots and cause root rot or slime. 

5. Don’t Overwater Your Plant

As mentioned earlier, due to a lack of light, the water will evaporate slowly, which can lead to various problems like symptoms of overwatering, nutrient lockout, root rot, and mold development on the plant. 

So, you need to water your plant minimally to ensure it does not experience such problems. Water your plant just enough that your plant grows. 

A good rule of thumb here is to weigh your pot before and water watering the plant to gauge when it is hydrated or dry. And only water the plant when the top inch of the soil is dry. 

Also, keep an eye on the runoff water. Ideally, you should aim for at least 20% runoff from the drain holes. 

6. Fine Tune the Indoor Climate

Without grow lights, you would need to pay close attention to your indoor environment, especially in terms of temperature and humidity.

Depending on the strain you are growing — if you have chosen them as per the recommendations above — you need to ensure the environment in your room is suitable for the strain and consistent. 

So, you might have to leave your aircon on for longer and even consider investing in a humidifier/dehumidifier for further fine-tuning. However, in most cases, as long as you have chosen the right strain, you will only need to give minimal thought to the environment. 

But we still recommend leaving the windows open from time to time to ensure a fresh supply of air in the room and avoid stagnation, which also keeps the temperature and humidity from rising in the room. 

Additionally, you should consider adding a small oscillating fan in your room to promote airflow. But your regular ceiling fan would work just the same in most cases if you don’t want to invest in an oscillating fan. 

7. Flush the Plant (or not) Before Harvest

In most cases, you will have to feed your plant-specific nutrients to support its growth, which is why you need to flush your plant when it is time for harvest. Doing so will remove any nutrients from the soil while also forcing your plant to consume all the nutrient reserves it has access. 

Flushing is based on personal preference, but you need to time it right. Ideally, you should flush your plant one or two weeks before it’s time to harvest. If you do it too soon, your plant may run off nutrients during the last lap of growth.

8. Keep It Simple 

Lastly, remember to keep it all simple. The reason you are growing cannabis indoors without grow lights is simplicity, so don’t overanalyze it. While growing cannabis, it is easy to get lost in the process and overthink or overdo certain things. 

Take it easy and solve issues when they arrive. Apart from that, be a good parent to your plant by maintaining and taking care of it whenever needed. And always monitor your plant. 

It would also help if you can keep a journal to track your plant’s growth. Allow you to blow our own trumpet, but nothing better than Growdiaries, eh? Remember, keep it simple. You don’t need to invest in monitoring sensors or purchase expensive apps to do this. 

9. Consider the Alternatives

There is no denying that growing cannabis indoors without grow lights is a compromise. So, consider alternatives that would otherwise work well for you. Some of the best ways to grow cannabis without spending a lot of money include the following:

  • Greenhouses: Small greenhouses are cheap and easy to build and can come in handy if you can’t grow cannabis in an open environment — they help you grow cannabis outdoors in an enclosed environment while still utilizing the sun’s light
  • Your backyard: But if you don’t have any outdoor restrictions, it is always better to grow cannabis in your backyard — it is cheap and easy
  • Your balcony: If possible, you should also consider placing your plant on your balcony; yes, there is a risk of your neighbor knowing, but at least your plant will get adequate light throughout the day without you having to move the plant around 

Summary: How to Grow Cannabis Indoors Without Grow Lights

Growing cannabis indoors without grow lights is quite straightforward. This is how you grow cannabis on a windowsill. Yes, you do need to put a little more elbow grease in moving your plant around, and your neighbor might spot your cannabis plant through your window, but otherwise, it’s fairly simple. 

All you have to do is ensure your plant gets enough sunlight through the window, and water minimally, and keep the room environment in check. Get the basics right and your cannabis plant will surprise you.

Cannabis is a resilient plant and there is a reason why we call it “weed” — it is literally a weed plant. It can grow in a variety of conditions, from the Himalayan slopes to the Afghan deserts. So why wouldn’t it grow in your bedroom? 

Once you have enough experience in growing cannabis and are ready to invest more time and money into this hobby, you should invest in good grow lights. Grow lights can take your indoor cannabis growth to the next level and it is almost crucial to have them when you want a good yield.

But for now, your big window will do just fine. 


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