Indoor Grow Guide

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Introduction Guide on Growing Cannabis Indoors

If you’re ready to take the leap into cannabis cultivation – then there’s no better time than now. Whether cannabis products from legal dispensaries are too expensive or you want to enjoy the fruits of your labor – growing your own cannabis indoors offers a rewarding experience.

However, growing cannabis indoors isn’t a cake-walk, which is why we created this beginner-friendly introductory guide on growing cannabis indoors. Read along to understand everything from A-Z about cannabis cultivation and how you can grow the best cannabis indoors.

Understanding The Cannabis Life Cycle

Before you make any substantial investments on equipment – it’s essential that you understand the most fundamental aspect of cannabis.

The cannabis life cycle determines nearly everything about your indoor grow room, such as space, lighting requirements, ventilation needs, and much more. If you do not understand the cannabis life cycle – you will likely fail in producing a substantial cannabis crop.

Without further ado – let’s break down the cannabis life cycle into the four main components.


Germination (Day 0-7)​

Before cannabis plants become plants – they are seeds. Each cannabis seed holds an unknown potential because it harbors a multitude of phenotypes. Cannabis cultivators won’t know which phenotypes are expressed until much later during the cannabis life cycle; however, you must understand that each seed is filled with potential.

The germination process occurs once the seed is exposed to two primary factors. These factors are temperature and moisture – and they create the cascade-like effects that propel cannabis seeds to germinate.

The moisture and warm temperature are signals to the seed to immediately release the radicle and shoot into the soil. The radicle is the original root, which follows gravity’s pull downward. The shoot is the above-ground section that will eventually form the stem, leaves, and, eventually, flowers.

Once this process is complete, the germination phase is over, and the next stage begins.


The Seedling Stage (Week 1-3)

The seedling stage in cannabis occurs after the germination phase is complete. During the seedling stage, cannabis plants are incredibly vulnerable. High winds, temperature, and pests pose a significant risk to cannabis seedlings, which is why you must take extreme care at this point.


Furthermore, cannabis seedlings do not require nutrients for a maximum of 3-weeks. This is because cannabis seedlings feed on a nutrient-rich embryo that was equipped with the seed. A common mistake during this stage in the cannabis life cycle is to feed cannabis seedlings – which results in nutrient burn.

Once cannabis seedlings have cleared the first hurdle of their lives, the next phase begins.


The Vegetative Phase (Week 3-4)

Once a cannabis plant reaches the vegetative phase, the root zone begins rapid expansion. This, in turn, allows for lush, vegetative growth above the soil line. Large fan leaves begin to develop, and your cannabis plant will start to look like a typical marijuana plant.

During this phase, an 18/6 (18-hours on and 6-hours off) light cycle is essential to keep the cannabis plant in a perpetual vegetative phase.

Depending on your needs, grow room, and more, the vegetative phase can last anywhere from 2-weeks to 2-months. It’s during this stage that your plants will exhibit their sex.


The Flowering Stage

Once your cannabis plant has reached the optimal size, it’s time to initiate the flowering stage. Since you’re growing indoors, you have the power to decide when your cannabis plant begins the flowering stage.

This is done by switching from the 18/6 light cycle to the 12/12 (12-hours on and 12-hours off) light cycle. By doing so, your cannabis plant will understand that it’s time to produce flowers and prepare for the end of its life.

It’s during the flowering stage that you will find out exactly which plants are female or male. Remember, cannabis flower production is only possible with females. If you find a male – discard them immediately or risk seeds in the flowers.

During the flowering stage, cannabis cultivators will see their plants grow in height upwards of 200% during the first two weeks. After the pre-flowering stage, the cannabis plant will produce cannabis flowers from top to bottom.

The flowering stage in the cannabis life cycle is the most anticipated portion for most cannabis cultivators. High levels of nutrients and an abundance of care are all associated with the part of the cannabis life cycle.

The flowering cycle typically takes 8-10-weeks to complete. Although certain cannabis strains can finish sooner or later, 9-weeks is the average. This means that you will need to prepare yourself for over 2-months of the flowering phase.

In total, growing a single cannabis plant from seed to harvest can take anywhere from 3 ½ to 6 months. Although this may sound daunting, it’s incredibly possible as long as you’re prepared.


Choosing the Right Strain

Cannabis strains are incredibly diverse. Thousands of cannabis strains are created each year, which means there are a plethora of phenotypes that exhibit drastically different traits. It’s these traits that can either make or break your indoor grow room.

However, you may wonder – what are phenotypes? A phenotype is an observable characteristic, which means you can see, feel, smell, taste, and experience each characteristic that a given cannabis strain produces.

So, what does this mean when growing cannabis indoors? It means literally everything. If your grow space is limited in size, then you’ll need a cannabis strain that does not branch wildly and grows small.

Alternatively, your grow room may be in your spare bedroom, which happens to be next to a nosy neighbor. In this case, you may want a cannabis strain that isn’t very pungent during its life cycle.

There are thousands of specific situations and an equal amount of cannabis strains that will suit your needs. The last example could be that you’re looking for a cannabis strain that produces a cascade of trichomes because you intend to produce concentrated extracts.

By picking the right strain for your needs – your cannabis grow room will thrive.

Here are a few things to consider when searching for the perfect cannabis strain for your indoor grow room.

The general size of a mature cannabis plant
Terpene profile
The aroma of a mature cannabis plant
The final yield potential
Flowering time
Branching characteristics
THC content
Trichome coverage
Once you’ve considered all of these factors with the space of your indoor grow room and your own personal needs – you’ll have a large number of potential cannabis strains to choose from.

Other Important Factors to consider

Now, it’s time to choose your indoor grow area. Is the grow room going to be in a spare bedroom, closet, or even a warehouse space? Whatever you choose, it must have certain aspects to be considered.

First, how many plants do you intend to grow? The size of your indoor grow room dictates how many cannabis plants you can grow. If you intend to grow a single plant, then a closet space will suffice. However, if you want to grow six large cannabis plants, then you’ll need a fair amount of space.

Second, you’ll need to ensure that your indoor grow room can power multiple HID lights. Indoor cannabis plants thrive from light that’s produced from high-intensity discharge lights, better known as HIDs.

You’ll need to make sure your indoor grow room can handle multiple HIDs – especially if you plan to increase the plant count in the future.

Next, you’ll want to ensure that you have direct access to water. If your indoor grow room does not have direct access to a water source, then you’ll have a full-time job of carting massive amounts of water back and forth to your grow room. Not only does this present a risk from a discretionary perspective, but it’s also a significant hassle.

Next, you’ll want to make sure you have adequate ducting or access to windows for ventilation purposes. Cannabis plants need regular air exchange to thrive, and ducting or windows provide exactly that.

Typically, indoor cannabis grows rooms have an intake fan to bring in the fresh air and an outtake fan to push hot air out of the grow room. This method keeps cannabis plants happy because temperatures are kept at a pleasant level. 

Without adequate air exchange, your cannabis plants are susceptible to a variety of problems that may end your cannabis crop prematurely.

Ultimately, your indoor cannabis grow room should allow easy access to your entire garden.

When we say medium, we mean the substance that your plant will grow in. A medium is a fancy way of saying the soil, water, or rockwool fiber. Choosing your grow medium is incredibly important for many reasons.

One of these reasons is the fact that your cannabis plant will grow in it for its entire life. The second reason is that the medium will dictate what type of nutrients your cannabis plant will receive. Let’s take a look at the various types of growing media and how they will affect your indoor grow room.

Remember, you’ll also want to consider the size of your grow room when deciding on which medium to choose. Large trays for hydroponic systems will not fit in small closets, for example, so you’ll need to choose accordingly.

Soil is by far the most popular medium to grow cannabis plants in. The reason behind this is because it’s cheap, readily available, low-maintenance, and natural.

When you grow cannabis in soil, you’ll need nutrients that are geared towards soil-use. This means that you should stray away from synthetic blends and utilize organic products. The beauty of soil is that the beneficial organisms that live within the soil act as a helpful barrier to the root zone.

Although cannabis plants grow slower in soil compared to hydroponics, soil offers a more natural approach that’s suitable for beginners and professionals alike.

Hydroponics is an incredible way to grow cannabis. Hydroponics uses water, air, and nutrients to produce gorgeous flowers in a short amount of time. However, hydroponics is considered much more difficult when compared with soil.

A true hydroponic system suspends the cannabis plant roots directly in aerated water. In this case, water is the medium.

However, there are other types of mediums that fall under the hydroponic category. These are rockwool, expanded clay, perlite, vermiculite, and even rice hulls. The important aspect to consider with these hydroponic mediums is that they are inert. This means that each of these mediums is chemically unreactive.

In the case of hydroponic mediums, synthetic fertilizers that are instantly available for plant uptake are commonly used. The primary reason why these types of nutrients are used is that most hydroponic systems do not utilize beneficial bacteria. 

Beneficial bacteria work in the soil by converting unusable nutrients into available forms; however, hydroponic-based nutrients skip this step. Although this results in incredibly fast-growing cannabis plants, it also means the plant will react quickly if it’s given too much or too little nutrients. 

Soilless mediums are those that are neither soil or hydroponic-based. Coco coir is a clear example of a soilless-based medium. Coco coir is a medium that’s made from the husk of coconuts and has risen in fame in agricultural production.

Coco coir can be reused like soil, but can also harness hydroponic-based nutrients. Coco coir is an incredibly versatile medium that can be optimized for growing cannabis indoors efficiently.

Once you’ve chosen your medium – it’s time to choose your nutrients. The nutrients you choose should coincide with your medium.

A balanced nutrient product that contains similar levels of N-P-K (nitrogen, phosphorous, and potassium) is sufficient for the majority of the cannabis life cycle, especially during the vegetative phase.

However, the flowering phase requires additional phosphorus and potassium, which means you’ll need an extra boost of P and K during the flowering stage.

However, choosing your nutrients is never a simple task. Do you go organic? How about beneficial bacteria? Bloom boosters? How about natural additives, such as bat guano or bone meal?

These are some examples that you’ll be posed with, depending on the medium you chose. If you go the hydroponic route, then you’ll need to purchase a readily available nutrient solution that does not significantly alter the pH.

If you go the soil route, then it’s recommended that you find organic-based nutrients that contain beneficial bacteria and microbes.

In the end, it’s best to take a look at reviews from others that have opted to use a certain product. The last thing you want to do is to use nutrients that contain harmful substances or provide inadequate results.

As we mentioned earlier – you’ll need to know how many plants you’ll grow before you can determine the number of lights needed. Lighting is one of the most crucial aspects of indoor cultivation because it powers plants to generate incredible yields.

However, which type of light will you choose? Examples of lighting that’s used to grow cannabis indoors are metal halide, high-pressure sodium, CFLs, and LEDs. Let’s take a look at each.

After reading through each type of light, it’s up to you to choose which fits your grow room best. You’ll need to consider the overall cost associated with purchasing the unit, powering the unit, and eventually cooling the unit. Which is right for you?

If you’re looking for the brightest and most powerful of the bunch, then there’s no other option than HIDs, such as metal halide (MH) or high-pressure sodium (HPS) bulbs.

These ubiquitous bulbs power most indoor grow rooms because they are by far the most well known. Although these lights push out an outrageous amount of light – they do have many downsides.

HIDs produce enough light to make your grow room look like an alien-abduction-in-progress because they consume massive amounts of electricity. This means that you can expect an equally large electricity bill and an increased level of heat.

Typically, indoor growers can choose from 300, 600, and 1,000-watt bulbs. The bulb is powered by a ballast, which may or may not come equipped with an onboard dimmer.

Generally, HIDs have a large light footprint and have enough power to penetrate dense canopies to promote large bud growth throughout your cannabis crop. However, you must consider the increase in heat and the overall cost of running multiple HIDs for months on end.

In general, MH bulbs are used for the vegetative phase because they emit a bright white or blue light. This wavelength of light is similar to that of the summer sun, which cannabis plants associate with vegetative growth.

Alternatively, HPS bulbs are primarily used during the flowering phase because the red and orange wavelength mimics that of the autumn sun as it strays across the horizon. It’s believed that the red and orange wavelength promotes flowering.

LEDs are the environmentally-sound answer to HIDs. LEDs offer cannabis growers with a powerful light that consumes a low amount of electricity. However, it’s essential that you understand that LEDs don’t come near the power that HIDs offer.

However, LEDs allow growers to place lights much closer to the plant canopy because of the reduced heat emission. Less heat and lower electrical consumption make for an ideal indoor growing environment that doesn’t cost an arm and a leg to maintain.

Many warehouse-stye grow operations utilize LEDs – so don’t think that these types of lights are only for closet cannabis growers.

However, LEDs are by far more expensive than HIDs. Although it should be noted that the savings in electricity will likely pay for the device over the course of a year.

Lastly, modern LEDs offer a level of customizability that allows growers to harness different lighting spectrums. It’s well known that all plants respond to certain wavelengths of light between 400-700nm.

If you go the LED route, it’s essential that you ensure that the LED unit utilizes diodes that operate between this range.

Compact fluorescent lights are low-wattage bulbs that are insufficient for growing multiple cannabis plants. However, they are ideal when you wish to supplement your HID or LED with additional light at a low cost.

CFLs emit low heat and consume a small amount of energy. In general, only small closet grow rooms that fit 1-2 plants will benefit from CFL lighting. Unless you are on an extreme budget, CFLs should only be used as supplemental lighting.

Air exchange and odor control are incredibly important for two separate reasons; however, these two units are commonly found tied together in the grow room.

Air ventilation in the grow room is accomplished with the help of inline and oscillating fans. Inline fans are used to bring fresh air in and push hot air out. Inline fans are connected to ducting to help route air in either direction efficiently.

It’s essential that your indoor grow room employs the help of an inline fan. Depending on the size of your grow room, you’ll need to choose which size is best for you. The larger the fan – the larger the grow room.

Indoor grow rooms suffer from outbreaks of pests and disease when there is an inadequate amount of airflow in the grow room. This is where oscillating fans come into play because they ensure that humidity remains low, temperatures don’t climb, and plant leaves move continuously.

Mold is the bane of every cannabis grower, and an oscillating fan can be the difference between a healthy harvest and a heartbreaking disaster. Depending on the size of your grow room, you may require one or multiple oscillating fans to keep your grow room mold-free.

Filters are necessary when growing cannabis plants because they emit pungent odors during most of their life cycle. However, the aroma of cannabis is strongest during the flowering stage. Even if your neighbors accept your cannabis hobby – it’s best to mask the smell with the help of a filter.

Filters are more commonly known as carbon filters, which use small grains of virgin carbon to grab unpleasant odors.

Indoor cannabis growers attach carbon filters to inline fans that are pushing air out. As the inline fan pulls air through the carbon filter, the smell of cannabis is locked into the carbon bed. This process removes the smell of cannabis effectively as it exits to the grow room.

Once again, depending on the number of plants, you may need a large carbon filter or multiple carbon filters.

The last thing you want during your cannabis cycle is to deal with neighbors’ complaints, or worse – a visit from your local law enforcement.

Lastly, you’ll need to consider which accessories and controls are best for your indoor cannabis garden. Let’s take a look at each.

Controls are used to automate various environmental aspects within the grow room. Here’s a list of environmental controllers for you to choose from.

  • Lighting timers
  • Irrigation controllers
  • All-in-one controllers
  • Nutrient dispensers
  • CO2 controllers

Each of these controllers can control the output, timing, or rate of various aspects within your grow room. Lighting controllers are necessary to ensure that the 12/12 or 18/6 lighting schedules kick on and off at the proper times.

All-in-one controllers are expensive units that automate your irrigation, lighting, and more. CO2 controllers dispense accurate amounts of CO2 into your grow room for optimized growth. As you can see, these units can play a significant role in the grow room.

When it comes to growing cannabis indoors, there are hundreds of accessories to choose from. Take a look at a few necessary accessories that you’ll likely need.

  • Support poles
  • Netting
  • Trimming scissors
  • pH meters
  • EC meters
  • PPM meters
  • Labels
  • Thermometer/Hygrometer
  • Rope Ratchets
  • And Much More

Each of these accessories will make your life easier while growing cannabis indoors. Although cannabis is considered a weed in many parts of the world, high-quality cannabis flowers are difficult to produce unless you employ the proper tools.

Are You Ready to Grow Cannabis Indoors?

Now that you’ve completed the introduction guide on growing cannabis indoors, it’s time to turn theory into practice. Remember, growing cannabis indoors isn’t a race. Mistakes will be made, and unforeseen issues will occur. However, it’s essential that you refer to this guide during moments of doubt.

Now that you’re ready to grow cannabis indoors, we recommend that you create a checklist with all the necessary tools. Plan, prepare, and take action – you have all the infor mation you’ll ever need to grow top-shelf cannabis indoors.

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Need a Full Guide?

We Have All The Right Techniques!

Download PDF

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