How to Grow Marijuana Indoors Beginners Guide

It takes about 12 weeks from when you first plant your marijuana seeds to fully grown plants ready to harvest. Here are the absolute basic things your marijuana plants need to grow indoors: Light, Water, Air, Soil or other Growing Medium, and Nutrients. It might seem scary at first to think about the daunting task of growing marijuana indoors, but this How to Grow Marijuana Indoors Beginners Guide will show you all you need to do from seeds to harvest. With some careful planning and the right equipment, you will be harvesting in no time.

How to Grow Marijuana Indoors Beginners Guide

Advantages to Growing Indoors

When you grow marijuana indoors you can grow all year round without having to worry about the seasons. Unlike outdoor growing. You won’t have to worry if your plants are getting the right amount of sunlight, water, or nutrients because you get to control every element of the process. You can monitor your plants and easily adjust the temperature, airflow, moisture levels, light exposure, and nutrients to ensure your plants are getting the right environment for each stage of growth.

Disadvantages to Growing Indoors

The amount of crops you can grow is limited by the amount of space you have indoors. Artificial lights may not be as effective as sunlight and you will need to supplement by adding additional nutrients. Without the proper ventilation and setup it will be hard for your plants to thrive, but hey, that’s what the guide is here for. To explain everything you need to have a successful harvest.

Grow space

The first thing you need to think about when growing marijuana indoors is where you are going to set up your grow space. It doesn’t have to be a large space. In fact, when you are first starting out it is better to use a small space like a closet or a corner of a room. This will save your time and energy and any mistakes you make along the way won’t be as costly as if you had set up a large space to begin with. The most important thing to consider is keeping the outside light out when your lamps are off and magnifying the light in your grow space to maximize growth potential. Wrap your grow space with thick reflective material that will block out light.

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You can also consider buying a grow tent with reflective material already inside like this Gorilla Grow Tent Lite. Some of them also came with ventilation systems to help keep your plants cool and to keep in unwanted odors from escaping your grow space.

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Or you can add one like this from iPower to your grow tent.


Finding healthy, high quality seeds is the first step to a successful harvest. You can buy them online, but make sure to pick a reputable vendor to make sure the transaction is legal. Plus, they will most likely have information on what variations grow well in small indoor spaces. Once you get your seeds, check them to make sure they are healthy. They should have small spots or a tiger-stripe pattern. If they are cracked they will most likely not sprout. If they are black, they are dead and you should request a refund. Store your extra seeds in cool, dry, night area in an airtight container. You can add a few grains of rice to keep out moisture. Marijuana seeds can last for five years if kept in the right conditions.

Alternatively, you can clone marijuana plants instead of starting from seeds. If you are interested in learning more about the cloning process, check out our Cloning Marijuana Guide.

Soil and Fertilizer

You will also need to decide your growing medium such a soil or hydroponics. Soil is the most cost effective medium and is very reliable. Hydroponic systems which use water and nutrients inside of soil to grow plants, need constant monitoring and nutrient adjustments. For beginners a small grow space and growing in soil will make the growing process easier to handle.

When it comes to soil and fertilizer quality, organic is best. You don’t want to risk using potentially harmful chemical and pesticides on something that is eventually going to be ingested or inhaled… Look for OMRI-certified (Organic Materials Review Institute) organic potting soil to ensure you are buying high quality soil.

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One good option is Black Gold All Organic Potting Soil because it contains pumice and perlite for great airflow and drainage. Also it already has organic fertilizers in it so you won’t have to add anything else to the soil for 3 to 4 weeks.

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If you are looking for a no fuss fertilizer solution, you can use a kit like Fox Farm Liquid Nutrient Trio Soil Formula. That way your plants will get the proper nutrients throughout the growing process without the hassle of researching what nutrients are needed as what stages.

Pots or Containers

You use basically any dark colored container to grow in but sure it holds about 3-5 gallons and has holes (or make holes) at the bottom for proper drainage. Make sure to thoroughly clean your containers so you don’t risk exposing your plants in any potential bacteria or mold.

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You can grow your plants any pot, but for the best air flow look for pots like Smart Pots which are made of stiff breathable fabric. This allows for more oxygen to reach your plants and offer better drainage than regular pots. The fabric prevents your plants from becoming root-bound or getting root rot because the pots air prune the roots. Because these pots dry out faster than regular pots, you will want to look for 5-gallon pots to slow the process.

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Another great option is an air pot like Superoots which has the same benefits of fabric pots but is made out of plastic with holes in the sides. Both fabric and air pots require saucers or shallow containers under them to catch any extra water or soil that may escape from the pot.


Watering your plants helps keep them hydrated and distributes nutrients throughout the pot. Just like the soil you use, you should only use the best water for your plants. So instead of using tap water, consider using filtered water to remove any unwanted impurities or chemicals .

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You can look for a water filter that attaches to your faucet like PUR or a water filter pitcher like Brita.  Keep an eye on your plants to make sure they don’t dry out and only use room temperature water. Younger planter will only need to be watered about once a week. Older plants will need to be watered about once a day. To test to see if your plants, touch the top of the soil. The soil should be moist but not wet. If it is too wet you risk getting root damage.

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If you are still unsure if you are watering your plants enough, you can use a hygrometer like Dr. Meter Moisture Sensor Meter to test the soil moisture level. To make watering easier, you can get a watering can with a long spout to get under the plant as it grows.

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There are also watering cans with a fertilizer dispenser attached like Aquavor so you remember to add fertilizer regularly.


Germination is the development of a plant after being dormant. The process can be started by providing moisture, air, and heat. It takes about 2-7 days for the seed to start to germinate and a white sprout to growing out of the seed. Here are a few techniques for germinating seeds:

Peat Pellets

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One of the easiest ways to germinate seeds is with peat pellets. First soak the pellets in water. Once they’ve expanded, insert the seeds ½ an inch deep into the pellet. Make sure the pellets remain moist throughout the germination process.

If you place the pellets in a disposable cup filled with soil, you can add water around the pellet so you don’t risk wash the seeds away from the top of the pellet. Also, this will allow for any easier and less stressful transfer process for your plants. When you see the roots pushing out the sides of the pellet, they are ready to transfer. You can carefully cut away the cup in a pot and bury to pellet and about half of the plant stem.


Fill a pot with soil and water it until damp throughout. Dig small holes at least a quarter inch deep, put the seeds in, and fill up the hole with soil. Keep the soil moist until you see small white sprouts start to push through the soil. In order for the seeds to germinate in soil the temperature needs to be around 78 degrees. You can wrap the top of the pot in plastic wrap to increase the humidity. It will take about 5-7 days for the seeds to germinate.


Fill a mug with warm water and put the seeds. If any of the seeds float to the top, remove them. Healthy seeds will sink to the bottom. Cover the mug so that no light can get in. The seeds will start to germinate in about 48 hours.

Paper Towels

Soak two paper towels in warm water and squeeze out the excess water. Place one paper towel on a plate and add the seeds. Cover with the other paper towel then with another plate. This should block out the light and give your seed a nice warm environment. The seeds should start to germinate in between 2-5 days. Remove the seeds as soon as the sprouts start to show.

Grow Lights

As soon as your seeds have started to sprout, they will need to be under a light source. Because you are growing marijuana indoors where they will only see artificial light, you will have to control their lighting schedule.

Fluorescent and LED grow lights are both great for marijuana plant growth. Fluorescent lights are easier to find and cost less, but you will most likely have to replace them more often than LED lights. LED lights produce less heat than fluorescent and use less energy. You can learn more about LED lights in our LED Grow Lights Guide. Whichever light you choose, make sure it is under 1000 wattage and you have 7000-10000 Lumens per square foot.

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Since you will most likely not be at home every time to manually turn the light on and off, it’s a good idea to get a programmable digital timer switch like Comforday 7-Day Programmable Digital Timer. This timer comes with multiple settings, two outlets, and a lifetime warranty. It also comes with a backup battery to save all your programmed settings.

Each cycle will require a different lighting schedule. Until they are about 3 and ½ weeks old, they will need about 18 hours of light and 6 hours of darkness. In the vegetation stage, they can get between 18-24 hours of light each day. The flowering stage is when you should switch to 12 hours of light and 12 hours of darkness each day.

You will have to adjust your grow lights as your plants grow to keep them 10-14 inches above the plant. You will want to keep fluorescent up a little higher because they produce more heat, which might burn or overheat your plant if it is too close.


To keep your plants from overheating or burning, it is important to keep the air in your grow space circulating to prevent the air from becoming stagnant and keep the humidity from building up which could lead to mold or rot.

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One or two small oscillating fans placed in opposite corners so provide enough air flow. Be sure to not point the fans directly at the plants. You’ll want to put the fans on one of the lowest settings so create a calm breeze throughout your grow space.


As soon as you see the sprouts are ¼ inch long, you can transfer them to a disposable plastic cup with holes cut in the bottom. Add some potting soil to the cup, make a hole about 1 inch deep, gently place the seed roots down into the cup, then carefully cover with soil. You will see a seedling start to pop out of the soil in a day or two. If you sprouted the seed in a peat pellet, you can transplant with the seed still inside the pellet.

This time is very critical because this is when your plants first start storing up their food supply for a healthy growth spurt. So don’t be worried if you think your plant isn’t growing fast enough. When the regular marijuana leaves start going, the seedling leaves will start turning yellow and staging. You will have to start paying close attention to your plant during this stage. Be sure not to over water or add any fertilizer to speed up the process because it could kill your plant. Seedlings require a lot of light. You should aim for 16-18 hours of light and 6-8 of complete darkness.

Transplanting Seedlings

When the leaves reach the edge of the cup, it’s time to transplant them into their permanent container.  If you leave your plants in the cups for too long, you risk them getting root-bound and the outside roots will start cutting off the water and nutrient supply to the rest of the plant. Water your plant 1-2 days before transplant so the soil is still moist but not too wet. This will help hold the soil and roots together for an easier and less stressful transplant for your plant. Dig a hole in the soil a little bigger and deeper than the plastic cup. Then carefully cut the plastic cup and transplant the seedling and all the soil in the cup into the pot. You can also run a knife along the edge of the cup and gently slide the plant out of the cup. Transplanting at night will give your plant enough time to rest and recover from the transplanting process.

Plant Health

Look out for nutrient deficiency and efficiency in your plants, especially in the first 4-5 weeks. Your plant should be green with strong, dense branches. If the stem of your plant is purple in the first month or so, don’t panic. Your plant is healthy, some stands of marijuana have purple stems in the beginning stages. High humidity levels in your grow space can increase the growth rate of your plants. In the growth period you can start off with 60% humidity and lower it by 5% every two to three weeks until you reach 40% which should be around the beginning of the flowering stage. Aim for a temperature of 70-80 degrees Fahrenheit is the seedling and vegetative stage when the lights are on and slightly cooler at night when the lights are off.  Also in the early stages you can increase the blue spectrum light level to accelerate growth.

Humidity and Temperature Control

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To make sure everything is working properly in your grow house, it’s a good idea to get a hygro-thermometer like this one from Extech. The display makes it easy to quickly check the temperature and humidity levels in your grow space.

Odor Control

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To cut down on odors when growing marijuana indoors, especially after your marijuana plants get closer to harvest time, you can install an inline fan with carbon filter like this iPower Fan and Filter Combo.

Harvesting Your Marijuana Buds

When the colors of the pistils (the little hairs covering the buds) change to a dark brown, the buds are ready to harvest. For the best results, start harvesting during the dark period as this is when your plant stores food to get ready to the “day” or periods of light. Lower the humidity in the grow space the last day before harvesting or a full 24 hour dark period may increase resin production. It’s going to take some time to trim the plants so make sure to set aside enough time to commit to harvesting your buds.

Carefully cut with a good pair of sharp garden shears the whole plant from the root and trim off the extra branches and large leaves. You can leave the branches with buds attached in v shapes. This will make them easier to hang them. You can also remove the buds and lay them out in the open air on a cookie sheet or mesh drying net. Leave the plants to dry for at least 7 days in 70 degree temperatures and 50 percent humidity and rotate them regularly if they are laying out flat.

Now it’s time to start curing the bud. This will increase the potency and quality of the buds. It will take about 2 weeks for the buds to cure. Trim the buds from the branches and trim off any remaining leaves on and around the bud. The easiest way to cure the buds is to put them in airtight containers. Be sure to open the containers a few times a day for 10 minutes to let fresh air in. Once they feel completely dry and don’t stick together, they are ready to use. Congrats, you just completed your first successful marijuana harvest! 

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We hope this How to Grow Marijuana Indoors Beginners Guide helped you learn everything you need to know on how to grow marijuana indoors.  If you are looking to make your first growing experience a little easier you can look for grow kits like this Gorilla Grow Tent Combo that includes all the equipment you’ll need to start growing. You can check out our Best Complete Marijuana Grow Kit Guide to learn more about it. 

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