Cannabis Cultivation

Indoor Cannabis Growers Guide

Indoor Cannabis Growers Guide

Table of Contents

This is a follow up guide to our Ultimate Outdoor Growers Guide. This guide will help and guide you as an indoor cannabis growers guide from Green Avenger Seeds. Growing Cannabis indoors comes with the same challenges and bonuses as outdoor growing. In this article we will discuss some of the great things about growing cannabis indoors and some of the not so great things that come with growing indoors. 

Whether you are a first time grower or have many years of growing awesome cannabis under your belt we hope this guide can provide you with indoor growing tips and tricks and how to get up and running with your new cannabis garden.

Advantages to Growing Cannabis Indoors

Cannabis Growing Indoors
Cannabis Grown by an Indoor Cannabis Grower

There are some excellent advantages to growing your cannabis crops indoors as opposed to outdoors. First you have more privacy when growing your cannabis indoors. You can control the smell, the view of your plants. You can start to flower your cannabis whenever you please. Unlike outside you are able to control the growing space environment perfectly. 

Growers never have to worry about a big rainfall, in the fall causing mold and Powdery Mildew issues. You have complete control over your temperature indoors, and are able to grow very consistent crops over and over all year long. 

What are the Laws in Canada and the United States for Growing Cannabis?

Before you start growing any cannabis indoors (or outside for that matter) it is best to check your local cannabis laws, in your country, province or state. In the United States cannabis cultivation laws differ from state to state. If you choose to grow in an illegal state be aware of the laws, if you are caught you will need to know them. If you live in a US state that has legalized cannabis, check how many plants you are allowed to have on your property at one time. Normally there is a plant count limit. 

In Canada growers are allowed to grow up to four plants in most provinces, check your local provincial laws to make sure you are allowed to cultivate cannabis indoors at home. 

This is an indoor cannabis growers guide so we will not get into laws here however, as a indoor cannabis grower we suggest that you check them before starting any indoor cannabis garden.

Indoor Cannabis Growing Solutions

One of the most important things about starting to grow cannabis indoors is where you will start to grow your indoor marijuana. Finding an indoor space solution is very important to grow quality cannabis.

Cannabis Growing Indoors
Indoor Cannabis

The Size of your Growing Space

When picking a grow space it is important to make sure the space is large enough to house your plants. It must not only be tall enough for your plants to grow but also wide enough for the pots and the amount of cannabis you intend to grow. Depending on the strain of cannabis you would like to grow, it can grow every tall, sativa strains can grow up to 15 feet tall if left untrimmed. Indica strains will grow shorter without trimming however they too can grow very tall if left untrimmed indoors.

How many Cannabis Plants do you Intend to Grow?

The size of your space will depend on how many plants you are allowed, or intend to grow. It is a good idea to consider the size of your cannabis pots and how many can fit in the space. You will not be able to fit 10, 5 gallon pots in the closest growing space. Likewise you will not want to have 10, 1 gallon pots in a warehouse garden. Pick a spot that will fit the size of the pots that you intend to use. We have a great guide on picking cannabis growing containers here.

What Space will you grow in?

Picking a great space to grow has a few different factors. It must be insulated from heat and cold. It should have reflective walls that will reflect your light onto the plants in the space. Flat White paint works very well for this. You can also buy white plastic for the space, or another reflective material for your cannabis space.

How do you Intend to Grow your Cannabis?

There are really two ways to grow cannabis indoors, either in pots with soil medium or soilless mediums or hydroponically. We recommend that new growers grow organically in soil with pots.  Growing organically is far more forgiving than growing hydroponically. If you are setting up your growing space to grow hydroponically, you will require more electrical wattages to run pumps, and timers. You will also require more area in your grow space for water, nutrient reservoirs, hydroponic growing systems.

A Bunch of Indoor Cannabis Plants
Cannabis Plants Growing Indoors

Can your Electrical System Support the Electrical needs

Before you do anything or even consider a cannabis growing space, it is important to understand if the electrical in the space can support the needs of your equipment. Most electrical breakers in new homes are 15 AMP 5 to 6 plug in outlets (This depends on your electrical code) 15 AMP will support about 1200 Watts of electrical for these plugin outlets. You will need to run lights, fans, exhaust fans, and perhaps water pumps. Keep this in mind during your set up. You may have to upgrade your electrical panel breaker to a 20 or even a 30 AMP breaker to run everything safely in your new space.

If you are unsure about these things we recommend that you hire a qualified electrician, to do this work for your space. For a couple hundred dollars it can save burning your house to the ground. Never mess with electrical yourself, if you don’t know what you are doing, or bypass any work done by an electrician.

Always Keep Electrical off the Floor

In a grow area you will inevitably get water on the floor of your growing space. Never leave ballasts, extension cords, lighting cables, plugs on the floor of the growing space. This can lead to very serious consequences like electrocution.

Ventilation in your Growing Space

Ventilation is another very important factor when picking your indoor growing space. The plants will need fresh oxygen and CO2, and need to remove old used air that no longer contains CO2. The best indoor cannabis grower spaces have easy access to removing old state air and bring in new fresh air (preferable from outdoors). Growing great plants will require the grower to remove and add fresh air into the growing space every five minutes. 

Keep in mind when picking a space that you will need to run ducking, and ventilation fans to and from an indoor growing space that you should choose. This is something that is best to think about upfront before picking the space. 

Waiting till after your spot is set up can cause some real headaches for you and your plants.

Indoor Grow Space Temperatures

Can you control the temperatures in your growing space? Indoor cannabis needs the right range of temperatures in order to grow. When the temperatures fall out of this range in this space the plant’s growth will slow, and it can even kill the plants. 

The grow space should have insulation to help the room maintain a temperature between 69.8F (21C) and 78.8F (26C). This is the best temperature for cannabis to grow in your room. 

If you are unable to keep your space under 78.8F (26C) you will need to consider using an air conditioner unit to keep your space cool in the summer. Likewise if you are unable to keep it above 69.8F (21C) you will need to have some form of heating the space. Many times a good space heater will work for this.

Can you Keep your Space Dark for 12 Hours a Day?

Flowering cannabis depends on the grower being able to keep their room free of light for 12 hours out of 24 hours every day for 8 to 12 weeks. There can be no light getting to the plants during their dark period for 12 hours whatsoever. If you are unable to keep the space dark the plants will either not flower or the plant will grow flowers that turn to male in the middle of the flowering period. When this happens the plants “hermaphrodite” and pollinate themselves.  

This will create cannabis flowers that create seeds in the harvested cannabis crop. If you are trying to harvest seedless cannabis flowers then you will need to keep the space dark for at least 12 hours.

Keeping Your Indoor Cannabis Growing Space Clean

We see many growers that forget this part of picking a great growing space for your plants. How hard is it going to be to keep this space clean? Keeping your space clean during your cannabis growing is of the utmost importance. Keeping your garden space clean will help with pests, bugs, fungus, mold and powdery mildew. Helpful things to keep in mind when it comes to keeping your space clean. First a flat waterproof floor will help keep the room clean. Having a floor like this will be easy to keep clean. You never want any cracks or ridges in the floor for bugs and mold to hide out. 

Having a water source in the growing space is also another advantage to growers. You use this source to clean your space and for watering your plants. 

Keeping the air clean by having great ventilation is another important reason to keep a room clean. Cannabis plants will take in anything around them including in the soil or in the air.

Growing in an Indoor Cannabis Growing Tent

If you do not have a good space to use, you may want to consider a good quality cannabis growing tent to grow in. These grow tents come set up and ready to grow inside of. They are enclosed and are reflective inside. They only take a few minutes to set up, you can also buy them as a kit, and they will come with the grow tent, lighting, ventilation, smell control and ducking. You will still have to place them somewhere that has the correct temperatures, and access to good ventilation. 

These grow tents come in many shapes and sizes to fit where you would like to place them. It’s a good idea to measure out the space before ordering so you can order the correct size and save the hassle of having to return it for another one. 

You can read more here about buying a good grow tent.

Indoor Cannabis Plants in a Grow Tent
Cannabis Growing In an Indoor Grow Tent

Lighting for your Growing Space

Lastly you will need to provide a light for your growing space that will be enough to cover the space and keep the plants growing strong. Since this is an indoor cannabis growers guide we will not get into too many details on growing lights just a basic overview of what you need for lighting your indoor cannabis grower spaces. If you would like to read more about picking a great light for your cannabis growing space you can read our guide here. 

You will want a grow light that will provide enough coverage for the space you intend to use. There are two types of lights that we recommend, HID and LED lighting. We recommend LED light if you can afford the upfront cost of the light. HID lighting in your room will provide great lighting however it is cheaper to buy upfront but will cost far more overall to run over time due to energy costs. 

LEDs are far more cost efficient to run for energy, but they do cost more upfront to purchase. They also have a far better spectrum of light. You can read more about lighting spectrums in our Cannabis Lighting Guide here.

Grow lighting is one of the most important things when starting your growing space set up. Cannabis is a very light hungry plant, meaning that it will need a bright full spectrum light to grow and most importantly flower well.

What do you need to set up your Growing Space?

This list is by no means extensive; however it is a good list of all the things that you will need to get a basic space set up. 

  • ISO 70% Alcohol for Cleaning
  • A reflective material or paint (Not needed if growing in a tent)
  • An Inline fan and filter
  • Growing Light
  • A fan to move the air around the plants in the growing space

Setting up Your Indoor Growing Space

Now that you have picked a space for your growth using the information above it is now time to start setting up. Setting up your indoor cannabis growers space takes some time and effort unless you are using a grow tent. Even a grow tent will take a bit to get set up correctly. 

First thing first you will want to clean your new growing space very well before doing anything. Use 70% ISO alcohol, as it will stick to your surfaces and kill anything that may be on them to attack your plants. Then wash everything down with dish soap and water.

Cannabis Growing Indoors Under LED
Cannabis Growing Indoors Under LED Lighting

A Note on Grow Room Timers

Timers are a very important but overlooked equipment for setting up a grow space. You will need them, and if you go cheap they could ruin your cannabis grow in a few different ways. They are used for running things like pumps, lighting, and ventilation. 

If any of them fail in the middle of your growth period, you can end with seeded cannabis flowers, unwatered plants, or plants that burned to death in the heat. Don’t skimp on the cost of timers, buy good timers for your space it could save you some serious headaches down the line.

Preparing Your Indoor Cannabis Growers Space

Now it is time to get things set up in space. You will want to make the walls reflective, with flat white paint or reflective materials. Get all the material ready for the space that you will be using. Having easy access to everything will make the process go much smoother the first time though.

Setting up Ventilation for your Space

Set up the ventilation next in your space. It is always better to pull air out from space than to bring it in. Doing so will mean that you can bring air into the space passively saving costs. Every time air is expelled in front of the space, new fresh air will be pulled into the space to replace the old stale air. 

This is done with timers, they should be set to expel the air every 4 to 6 minutes in your growing space. Or you can use fan speed adjusters to slowly remove the old air consistently, and bring in fresh air if you do not want to use a timer.

Using a Carbon Filter to Control Smell

If you would like to keep your garden space on the down low, we recommend getting a good carbon filter to use in your growing space. Carbon filters work by removing the smell as the air flows through them out of the cannabis growing space. They come in different sizes and you can pick the one that best suits your space. You can get them in 4 inch, 6 inch, 10 inch and 12 inch. These are the sizes that will fit your inline fan or ducking. 

They are typically hooked up inside the growing space to your inline ventilation fan. They work best by pulling air through them and to the outside of your growing space. At the same time removing the smell of your flowering cannabis plants.

Setting Up your Indoor Garden Lighting

Now that your ventilation is ready it’s time to set up your grow lighting. Depending on the size of our space or tent, you may need many lights to cover your space or only one. Growers will want to make sure the height of the growing light can be adjusted as the plants grow to flower. The light should be about 18 inches above the top of the plants at all times. You can use growing light hangers to do this, to move the lighting up and down over the plants. 

Be careful not to get the lighting too close to the plants, it can burn the tops of your growing plants if hung too close. 

Also make sure the light has hung securely, that it will not break free and fall on your plants, causing damage at best, and a fire at worst.

Other Things to Consider In your Space before you Start Growing

Wow! You are almost ready to get growing in your new space. However there are just a couple more things to consider for your space that we will review. 

Growroom Space Humidity

Humidity in the grow space can be a concern depending on where you space is located and the outdoor environment you plant to grow in. In very dry climates you may need to add humidity to the growing space with a humidifier. If you grow in a climate that has very high humidity you may need to have a spot for a dehumidifier. Here are is the humidity you should keep in range for different stages of cannabis growth:

  • Vegetative Cannabis Growth: Should be kept in the range of 45% to 55% until flowering
  • Early Flowering Cannabis Growth: Should be kept in the range of 40% to 45% 
  • Late Flowering Cannabis Growth: Should be kept in the range of 30% to 40%

Growing Cannabis in your New Growroom

Now your new grow room is all set up and you are ready to move to growing your fresh new cannabis plants. Everything should be working in the indoor environment to keep your plants growing healthy and happy, after accounting for everything in the room setup. You are now ready for the new steps, growing your cannabis plants!

Getting the Best Indoor Cannabis Seeds for your Garden

Indoor Cannabis Seeds Close Up
Green Avenger Indoor Cannabis Seeds

Now you need some seeds for your indoor garden space. There are many great cannabis strains out there for indoor growing. You will want to read about each marijuana strain and make sure it is suitable for cultivation indoors. Most seedbanks will list where the strain will grow best, either outdoors, indoors or in a greenhouse. If you would like to read our outdoor cannabis growing guide you can do so here. 

These are some seed strains that we have tested and grow very well for new indoor cannabis growers. They do very well growing inside, and have very nice indoor yields for our new indoor cannabis growers. They are very beginner friendly cannabis strains and grow great indoors!

Choosing the best indoor cannabis seed strain is very important to a successful cannabis garden.

If you would like to purchase these cannabis seeds they will come with a germination guarantee and we always stand behind what we sell to our customers.

Choosing A Growing Medium for your Indoor Garden

Your cannabis plants will be spending all their time and growth in their cannabis growing medium indoors. Picking a great growing medium will keep your plants healthy and thriving. Pick a growing medium that has proper PH, a good supply of nutrients and excellent drainage. You can read more here about picking an awesome cannabis growing medium for your garden. We recommend growing using organic growing methods, you can also read more about organic cannabis growing here.

Indoor Cannabis Growing Medium
Indoor Cannabis Growing Medium

Growing Indoors Seedling Stage of Growth

Now it’s time to germinate your new seeds and get growing in your new space. There are many ways to get your seeds germinated and we have a great marijuana seed germination guide here for growers. 

Once the plants have germinated place them under your growing light, as the seedlings are still young keep the light a bit higher then for a more mature plant. We suggest 24 inches until the plant has its first set of true leaves then you can move it closer at 18 inches.

Growing Indoors Vegetative Stage of Growth

Now your plants should be in full swing in your grow room or grow tent. Make sure you monitor your marijuana plants daily for PH issueswatering issues, and nutrient deficiencies or overuse. It is very important for indoor cannabis growers to keep on their plants regularly for healthy growth. If you start to run into any issues in this stage of growth the links above can help you with these. In this stage of growth you can keep your light on a timer for 16 hours on lighting and 8 hours off lighting. 

Your plants should be green, and no yellowing of any leaves.

Vegetative Indoor Cannabis Plants
Indoor Cannabis Growers

Pruning Cannabis Plants Indoors

All growers growing indoors have to prune their cannabis plants at some point. You will need to remove leaves and branches from the plant, or use Low Stress Training techniques to keep your plants from growing too large and into the lighting. It is far more important to use pruning indoors than outdoors to keep the plant growing well. Low Stress Training or pruning cannabis indoors can help to keep an even growing canopy for when the grower starts to flower plants. 

Indoor cannabis growers can also use defoliation techniques to remove leaves from blocking the light getting to flowering sites during this stage of growth. You can read more here about how to use defoliation to grow bigger and better cannabis buds.

Using Plant Support for Indoor Cannabis Growers

As your plant gets larger it will most likely need some form of support as it grows larger. There are a few different ways that a grower can support their indoor cannabis plants, first is by using a netting to keep the plants upright without falling over. These nets come in different sizes for spaces, they can be 2X2, 3X3, 4X4 and larger. They come with larger holes in them that the plants can be inserted through.

Another method to support plants are bamboo stakes, they can be pushed into the plant growing medium. The plant is then tied to the bamboo stake to keep it from falling over. 

Supporting the plants is not as important in the Vegetative growing stage however it becomes very important when the plants flowers start to get heavier. You can read more here about keeping your cannabis plants branches and stems strong. 

Nutrient Needs for Vegetative Indoor Cannabis Plants

Cannabis that is growing in a vegetative state requires all nutrients for proper growth. They will require a good supply of nitrogen to grow fast and healthy in this stage. You can add extra nitrogen if you see that any of your cannabis leaves are turning yellow at the bottom of the plant. This is a sure sign that the plant needs more nitrogen and is taking nitrogen from the bottom leaves to keep the main growing tip healthy and growing quickly. 

Growing Indoors Flowering Stage of Growth

Now you are ready for the best part of growing cannabis indoors, flowering your plants. It is time to switch your growing lights to 12 hours on and 12 hours off lighting. This will start your cannabis plants into a flowering stage of growth. When this happens the plant will start to “stretch” and grow taller very quickly in the first two weeks of the flowering stage. Keep a close eye, so that the plants don’t get close to the hot lighting. You may want to use low stress training to help keep your plants from getting too tall for the height of the grow space. 

This is the most important part of the growing process, keeping the humidity in the right range will help to prevent Powdery Mildew and Mold (Bud Rot) from getting on and into your cannabis buds. You can read more about bud rot here. Also having good air flow from your fans moving the air over the leaves and buds will help with this as well. 

After switching your lights to 12 hours of darkness per day, most cannabis strains will take from about 8 to 12 weeks to fully finish flowering and be ready for harvesting.

Indoor Flowering Cannabis Plant
Indoor Flowering Cannabis Plant

Nutrient Needs for Flowering Indoor Cannabis Plants

Now that the plants have started to flower they will need less nitrogen, and more potassium and potash to help them grow larger and denser cannabis flowers (buds). You will most likely need to supplement the soil for this, or switch to a bloom nutrient for soilless or hydroponic indoor growing. Watch closely for any signs of nutrient deficiencies in this stage. When this happens it can hurt your bud potency and yield as well.

Growing Indoors and Cannabis Pests

Pests are a big grower concern for outdoor cannabis growers and it is no different for indoor cannabis growers as well. keeping your room free of pests inside starts with two many things. The first being as discussed above keeping the grow room as clean as possible, and then a bit cleaner ha ha. Next is keeping the pests out of the room and in the first place. Never visit an outdoor garden (doesn’t matter what type of garden here), then visit your indoor cannabis garden. You never know what you are tracking in your shoes or boots from outside. 

You could also have mold or powdery mildew spores on your clothing or in your hair. Keep the windows closed in the grow room so bugs are unable to get into the room and attack the plants. There are many flying pests that are able to fly into your growing room. Before you know it they are sucking or chewing your plants until they are dead. 

If you do get attacked by any of these things there are ways to remove them from your room, you can read about how to get rid of spider mites. This is one of the main pests you may have to deal with.

Close up of Thrip Pest Damage Cannabis
Close up of Thrip Pest Damage Cannabis

Dealing with Cannabis Bud Rot Indoors

One issue that many growers face in the final weeks before harvesting cannabis is mold otherwise known as but rot in their cannabis buds. As the buds get dense in the last couple weeks of flowering, they build up humidity in the inner parts of the buds. This is a breeding ground for bud rot. Most growers don’t even see it until it is already ruining their beautiful cannabis crop.  

If you get bud rot in your buds, this article can help you beat it and identify it on your marijuana flowers.

Cannabis Bud Rot
Bud Rot on the Top Of a Cannabis Plant

Harvesting and Curing Your Indoor Cannabis

Congratulations! Now it’s time to harvest your indoor plants. It is important to know when your cannabis is at its peak harvesting point. While it’s a good idea to keep track of how many weeks your plants have been flowering, it is not the best way to tell when to harvest your plants indoors.

Using a Jewelers Loupe and Checking Trichomes for harvesting

The best way to tell when the indoor cannabis growers plants are ready for harvest, is to buy, and use a jewelers loupe. This is a small microscope that you can check the small trichomes on the plant’s flowering buds. When looking at them up close they should not be clear. They should all be a cloudy white color and there should be some that are starting to turn an amber color. This is by far the best way to tell your cannabis plants are ready for harvesting. 

Indoor Cannabis Trichomes
Cannabis Trichomes Close Up

How to Harvest your Cannabis Plants

Now comes the time to cut down your plants and start to dry them. Some growers just prefer to dry their plants in the same room as they grew them in. You are already able to control the humidity in the space and this is important when drying your plants. 

You can either trim your plant of leaves as soon as you harvest them or wait till your plant is dried well before trimming access leaves. It will make little difference on which one you choose overall. The most important thing after cutting your cannabis crop is to start drying as soon as it is cut. You will once again want to keep everything as dry as you can. At the first you want to get your plants dry quickly before any mold can destroy your beautiful cannabis buds. 

After your buds are dry it is time to start curing them. Curing cannabis involves slowing down the drying process and keeping the plant’s smell and flavors intact. We have a great guide, for harvesting and drying, curing your cannabis you can read here.

Harvested Indoor Cannabis Buds
Harvested Indoor Cannabis Buds

Final Thoughts for Indoor Cannabis Growers

While growing cannabis indoors can cost more than growing outdoors, it can quickly pay for itself over buying cannabis. Growing your cannabis, or cannabis medicine is very rewarding and we hope this indoor cannabis growing guide can help you start, plan and grow the best cannabis crops possible indoors. 

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