How to Grow Weed Indoors Without Grow Lights: A Windowsill Guide

Yes, you can grow weed indoors without grow lights: put a couple of plants in a big, sunny window that gets at least six hours of direct sun a day, grow in summer, pick the right strain and rotate the plants daily. Traditionally, an indoor cannabis grow relies on artificial lights to mimic the natural light cycle plants need to grow and flower, but natural light and a few smart tricks can do the job on a small scale.

Here's how to grow cannabis indoors without depending on artificial lighting, adapting your technique to what the plants and your space actually need.

Can you grow weed indoors without grow lights?

Growing weed indoors usually means using artificial lights to imitate the natural light cycle plants need to grow and flower. Still, growing cannabis indoors without them is totally doable, as long as you make the most of natural light.

For example, you can set a couple of plants on a bright windowsill and still get decent results.

So... does an indoor grow without lights really work?

Grow tech has come a long way and can give you a perfectly controlled environment, but an indoor grow without artificial lights can still be a solid option, especially if you've got plenty of natural light.

It's true that perfectly controlled grows usually produce bigger plants and heavier harvests. But if you only grow now and then, or you're working on a tight budget, a low-budget indoor grow can give you respectable results.

Keep in mind that even without grow lights, your plants still need enough natural light to thrive. Without it, the plant can't photosynthesize properly, and that hurts growth and yield. So if you decide to grow indoors without artificial lights, make sure your plants get as much natural light as possible.

Pros and cons of growing cannabis indoors without grow lights

Pros of growing weed indoors without grow lights

1. Lower cost Growing weed indoors without artificial lights can be way cheaper. Quality grow lights, like LEDs or HIDs, are expensive, and the electricity adds up too. Sunlight coming through your window, on the other hand, is free. And skipping the grow tent and exhaust system cuts costs even more. Without grow lights, the only things you really need to invest in are:
   • Seeds
   • Containers
   • Growing medium
   • Fertilizer
   • Water
2. More freedom Ditching lights and grow tents gives you more freedom. High-end grow setups take up space and can be noisy and glaring, while a couple of plants on a windowsill barely changes your daily routine. Growing in natural light also means less maintenance and fewer adjustments, which keeps things simple.
3. Easier to grow Growing weed without artificial lights simplifies the whole process. With less gear and zero power use, a natural-light indoor grow is much more straightforward. That makes it an appealing option for beginners and anyone who wants a low-hassle grow.

Cons of growing cannabis indoors without grow lights

1. Stretchy plants Without enough light, cannabis plants can stretch out looking for it. That stretching can make plants lanky and too tall, messing with their structure and the space you have. For good results, you need a big, well-positioned window that gets steady light.
2. You need the right windows To grow weed without artificial lights, you need big windows facing the right way (south, southwest or southeast in the Northern Hemisphere; north, northwest or northeast in the Southern). Without that, growing may not be doable. A small window facing away from the sun probably won't give you enough light for a successful grow.
3. Smaller harvests Harvests from natural-light grows are usually smaller than what you'd get under grow lights. Seed banks may advertise big yields, but on a windowsill you'll probably pull 30 to 60 grams (about 1 to 2 oz) per plant.
4. Smell and discretion Unlike grow tents that keep odor in check, a windowsill grow can make your whole place smell like weed. If that's a problem, there are low-odor strains. Plants that can be seen from outside can also catch the attention of neighbors or even the authorities.
5. Time and handling Plants grown in natural light need to be moved often so they get even light. Photoperiod plants need periods of total darkness, so you'll have to move them to a dark space if your curtains can't guarantee it. You can also shift the plants around during the day to get the most sun.

How to grow weed indoors with natural light, step by step

Growing cannabis indoors with natural light is a solid option if you want a simpler, cheaper approach. Here's how to pull it off and get the best results.

1. Grow in summer

To make the most of natural sunlight, summer is the best time to grow. Long, sunny days give plants the light they need to thrive. Around the spring and fall equinoxes, light levels are also good enough for cannabis to grow. Plants need at least six hours of direct sun a day, plus several more hours of indirect light. Dark, cloudy days, especially in winter, won't give them enough light to grow healthy, which can stall them out or even kill them.

2. Pick the right strain

Your choice of strain is crucial for a successful natural-light indoor grow. Sativas are ideal for warm spaces and will thrive in windows that get lots of summer sun. Indicas, on the other hand, are better suited to cooler spaces, like rooms with air conditioning or less direct sun. Choosing the right strain can make a big difference in the quality and size of your harvest.

3. Find a big window

The bigger the window, the better for your grow. Big windows let in as much sunlight as possible, which is essential for plant development. If you can, choose a window that isn't blocked by buildings or anything else that could cut off the light.

4. Prioritize direct sunlight

Direct sunlight is key to getting the best growth out of cannabis plants. If you have several windows to choose from, pick the one that gets the most direct sun during the day. South-facing windows are best in the Northern Hemisphere, while north-facing windows are best in the Southern Hemisphere. East- or west-facing windows can work too, though they'll get less direct light.

5. Window height

Windows on the upper floors of a house usually get more light and are less blocked. If you have the option, put your plants by a higher window.

6. Good ventilation

Opening the windows now and then lets fresh air circulate, which is key to avoiding a buildup of humidity and stale air that can hurt your plants. It also helps clear out that unmistakable weed smell.

7. Move your plants around

Moving your plants from one window to another during the day can help them soak up more sun. If you have windows facing different directions, follow the sun to get the most out of the available light.

8. Rotate your plants

To keep your plants from leaning toward the light, rotate them regularly, at least once a day. That keeps growth even and prevents lopsided plants.

9. Go easy on the water

Since there's less evaporation than in a grow under artificial lights, don't overdo the watering. Too much water can encourage mold and other pathogens. Water only when needed and make sure your growing medium drains well. A handy trick is to lift your containers to know when to water, comparing how heavy they feel when the medium is dry versus when it's wet.