How to Grow Cannabis Indoors: The Beginner’s Guide
July 20, 2018
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How to Grow Cannabis Indoors: The Beginner’s Guide

All you need to know to get started...
Nicole Richter / Updated on July 20, 2018

How to Grow Marijuana Indoors

[The information in this article has under no circumstances been created for – or is intended to be used for – illegal purposes. Growing/cultivating cannabis is illegal in many U.S. states, and we therefore advise that all readers be familiar with current laws and regulations in their region].

 

So you’re thinking about growing cannabis indoors and wondering how to do it, eh? Well, on behalf of the marijuana cultivating community, welcome to the family! Growing your own cannabis plants is certainly no cake walk, but in time (and with plenty of experience), it can be one of the most rewarding things you’ll ever do.

For any potential first time grower, getting started is actually the biggest roadblock that you’ll likely face. Among other things, you’ve got to find a quality place to cultivate, obtain the proper growing equipment (including of course the actual marijuana plants or seeds themselves), and be able to set aside the time (and money) to maintain the plants so that they can stay healthy and strong throughout the maturation/flowering process.

And of course, you’ll want to make sure that you’re operating within the boundaries of the law before getting started with anything. Growing weed is still illegal in many U.S. states, so make sure that home cultivation is allowed in the area you’re living in before setting up any kind of an operation.

That being said, we hope that this guide to indoor cannabis growing sets you off on a long, productive, and fruitful (no pun intended) voyage of marijuana cultivation!

Step 1: Choose the Perfect Cannabis Grow Room

cannabis grow

Naturally, the first thing you’ll need to do when thinking about setting up an indoor cannabis grow room is to… choose a room to grow it in!

Of course, your growing/cultivating space certainly doesn’t have to be an actual full-size room. In fact, a typical grow room from an average cannabis DIY’er might be something like a small tent, a cabinet, a designated space in a spare room, or even a corner in an unused part of the house.

When choosing your space, however, make sure to keep a few things mind so that you don’t have to abandon the project (and the plants) before it ever really starts:

Start growing from a little plot, and take little steps…

One of the most common mistakes that a first-time grower makes is choosing a grow space that is WAY bigger than what they actually need.

For your very first grow project, it would be wise to heed this advice: choose a little plot, and start out small!

By “small,” we mean nothing more than a few plants at most. In fact, you’re probably going to want to start with just one or two plants. There is an inevitable learning curve involved with growing weed indoors, and as such, you are bound to make some mistakes. The fewer plants you have, the fewer plants you’ll waste (and ultimately the more money – and frustration – you’ll save yourself!).

Even veteran cannabis growers run into mistakes and unexpected mishaps with almost every batch they produce, so while you probably won’t be able to prevent a failed grow on your very first attempt, the less plants you have will ultimately mean the less plants that are ruined.

…Cos you’ll be growing in a bigger plot in a few weeks!

Be advised, however, that it won’t take long to get the hang of things and really start producing some beautiful, flowering cannabis plants. If you’ve never seen a mature, full-sized female Cannabis sativa plant up close and personal, though, be advised that they’re not small. Even once they start producing the first hints of flower, you can expect the plants to double or even triple in size before reaching full maturity.

As such, even with a tiny growing space (like a small tent or cabinet), you’ll want to make sure that you have enough room for your plants – the last thing you want is for them to be well on their way to maturity, and then simply run out of grow room (at this point they’ll probably become stressed anyway and start producing seeds, at which point the yield will be more or less ruined).

Also, make sure that you leave enough space for your equipment (as well as yourself) to work in!

A clean space is one of the most important things to remember

Another thing we can’t stress enough when growing indoors is to make sure that your cultivating space is sanitized… and clean all around.

There are certain things you simply can’t control when growing outdoors, but when you take the project inside, you have no excuse not to keep the project neat, tidy, and free from any potential hazards and contaminants.

In order to maintain a clean space for growing, very carefully plan out a bi-weekly cleaning routine, and make sure to stick to it. By “cleaning,” though, be advised that we don’t mean spraying down your plants with Lysol or anything like that. All you have to do is use a wet microfiber rag to wipe up all the surrounding areas around the plant(s).

Marijuana plants are considered to be “bioaccumulators,” which means they pretty much “suck up” anything and everything around them (both in the air and in the soil). In order to keep potential contaminants out, make sure the surrounding growing space is as clean as possible.

Keep your grow square as “light-sealed” as possible

Another thing you’ll need to consider when choosing an indoor cultivating space is that you’ll want the area to be able to be sealed off from surrounding light sources (one of the requirements of most any quality grow room is that it be “light-tight,” so to speak).

Even though light is very important for the growing process and your plants will be receiving direct light the majority of the time, few first-time growers realize that periodic darkness (and complete periodic darkness) is equally as important for producing “yieldable” buds.

Like most living things, cannabis plants need their “rest time,” and if light from a surrounding source is seeping in while it should be dark, the (bud-producing) females will go into “survival mode” and cause them to produce male flowers. Of course, this is not good at all in terms of producing a high-THC yield.

Successful indoor growing will require these important things

Lastly, when choosing where to grow your cannabis, try and consider these last few factors in order to get the most out of you cultivating experience (and not to mention your potential yields):

  • Choose a secure place that will be safe from any “unwanted visitors” – this not only will ensure that your grow is protected from both animal and human intruders, but it will also allow you to monitor your plants carefully every day without having to be peeking over your shoulder all the time
  • Temperature and humidity concerns will always be an issue, so try and select a spot that is pretty well sealed off from fresh air from the outdoors
  • Convenience is just as important as anything else, so make sure your spot is safe, easy to get to, and easily accessible at any time — day or night

Step 2: Choose (and Use) Your Cannabis Grow Lights

cannabis plants

Naturally, the light source that you use in your grow room will play one of the most significant roles in determining the quality of the plants/buds that you end up with. Generally speaking, it’s recommended that you spend as much as your budget will possibly allow on a good lighting set up – it’ll be worth it in the end, particularly if you plan on growing over the long term.

Here’s a basic rundown of the most popular types of cannabis grow lights being used today.

LED grow lights

If cost were no consideration, LED (light emitting diode) lights would no doubt be the preferred option for marijuana growers. These are highly efficient light fixtures for indoor growing that use little energy and create very little heat, and given that they contain more wavelengths across the light spectrum, they can lead to bigger yields and better quality plants.

The drawback, of course, is that they cost nearly ten times more than a decent HID setup. If you’re serious about getting into growing and don’t mind splurging some extra cash, definitely give LED some ample consideration (though be advised that there are a lot cheap, “scammy” LED options on the likes of eBay and Amazon, so do some homework to find a reputable brand).

Induction grow lights

Induction lamps are kind of an odd choice for indoor growers, but some companies have recently been adapting/marketing them for the cannabis industry, and they can potentially represent a decent value in terms of cost and efficiency.

The process of generating heat from magnetic induction was actually invented by Nikola Tesla in the 19th century, and basically, these types of lamps represent a more efficient option than fluorescent, yet are cheaper than LED and (some) HID setups.

HID grow lights

HID (high intensity discharge) grow lights are probably the most commonly used lights for DIY-style growing. All things considered, they typically represent the best overall value in terms of cost, efficiency, and ease-of-operation.

The main drawback however is that they require a fair bit of accessories in order to run properly, so the overall cost can ramp up pretty quickly depending on how much you’re willing to splurge.

For example, most growers will use two main types of HID lamps/bulbs depending on the developmental stage the plants are in. Metal halide (MH) bulbs are primarily used during vegetative growth, while High Pressure Sodium (HPS) are the preferred option for the mature flowering stage.

That being said, it’s not an absolute necessity to get both types of lamps – if you want to save some money and only get one, make sure you go with HPS as they are a bit more efficient on a watt-to-light-produced scale.

Also, since HID lights produce a substantial amount of heat, you’ll need to invest in a ballast and hood/reflector for each light. This is almost mandatory for controlling the temperature in your grow room, and the hoods will need to be hooked up to ventilation in order to flush out excess heat and maintain a normal ambient temperature.

Fluorescent grow lights

If you’re not sure whether you’ll stick with the whole indoor marijuana growing gig long-term, fluorescent lights may be the way to go as they’re generally much cheaper and easier to use than the other options.

Also, since they don’t produce much heat, they won’t need to be hooked up to any kind of an external ventilation system. They’re of course a little less efficient than the other options, but for novice DIY growers who will only be playing around with a single plant or two, they’re likely your best bet.

Pros and cons of grow lights

As we mentioned earlier, make sure to weigh out the pros and cons of each option when deciding on your grow light setup. The quality of your light source will ultimately determine the quality of your plants (as well as the potency of your buds), so like we said, don’t be afraid to spend as much as your budget will possibly allow.

Step 3: Fresh Air is the Lifeblood of Healthy Cannabis Plants

growing marijuana indoors

Since your grow space will be indoors, obviously by “fresh air” we’re not referring to actual outside air.

Rather, what you need to do is make sure that you have a good flowing of air across your entire plot. Depending on the size of your grow room, this can simply be done with a portable fan on one side of the space (usually sitting on the floor), and an exhaust fan on the other side up towards the ceiling.

Since warmer air rises, the exhaust fan will suck out all of the hot, stagnant air while the other fan provides a nice supply of cooler, CO2-filled fresh air. It’s no secret that plants need fresh air, and this technique will not only allow for a constant supply, but it will also help to maintain temperatures in a manageable region.

Most cannabis strains prefer an upper temp range between 70 degrees F and 85 degrees F, with a lower (lights off) range of around 55-75 degrees F. If you’re growing indica strains, they tend to prefer the cooler end of the range rather than the warmer.

Step 4: Develop a Control System and Monitor the Growing Process

Once you’ve chosen an appropriate grow light system for your plants (i.e. your lights and climate control equipment, which basically just consists of a regular fan and an exhaust fan), you’re going to want to set up some kind of a self-monitoring system to control it all, as we assume you won’t be able to spend 24 hours a day in your grow space.

Basically, the main things you’ll need are a 24 hour timer and an adjustable thermostat. The adjustable thermostat allows you to set your exhaust fan to come on once temperatures go above a certain degree, thereby allowing for a relatively stable temperature range and humidity level while saving a bit of energy and money.

The 24 hour timer is just as important. When the marijuana plants are in vegetative growth, you’ll want to have the light supply on for around 16-20 hours per day. Once they mature and reach the flowering stage, you’ll need to change it up to about 12 hours light and 12 hours dark.

Lastly, it’s not absolutely vital but we recommend investing in at least some sort of a pH meter so you can check on the quality of your water and soil regularly. If you’re growing in soil you’ll want to try and keep the pH between about 6 and 7, and if you’re growing hydroponically (in water), around 5.5 to 6.5 is an appropriate range.

Step 5: Be an Artist! [And Choose a Cannabis “Grow Medium”…]

how to grow weed indoors

After you’ve got the lighting/lamp operation set up and have figured out how to sync it to an automated 24 hr timer, you’ll then have to decide what medium you want to actually grow in.

When growing cannabis indoors, you’ve basically got two viable options: growing in traditional soil or growing in a hydroponic tray. Regular old soil is typically recommended if you’re growing indoors for the first time, as it’s cheaper, more straightforward, and more forgiving than a more advanced hydroponic system. Let’s take a closer look at each of the two options.

Soil vs. Soilless (And several things to consider about hydroponics)

Like we said, cultivating cannabis plants in soil is the recommended method for first time growers, as it’s simply easier, cheaper, and has less of a margin for error.

That being said, all soils are definitely NOT created equally, and it’s important to be selective and have an idea of what you’re doing when it comes to choosing a proper growing mix for your plants.

General run-of-the-mill soil will work OK as long as you periodically add nutrients to it along the way, but a good, pre-fertilized soil is the option of choice as it takes most of the guessing work out of the equation, and basically sets you up with a medium that will last until the plants are ready for harvest, with little maintenance along the way.

Organic growing of course is the traditional medium for growing cannabis indoors, and can work very well if done properly. All you really need is a quality soil with a proper nutrient-rich, optimized growing mix that contains things like bat guano and mycorrhizae bacteria, as well as other organic compost nutrients.

If you choose to go with many of the “all-in-one” automated hydroponic setups out there on the market, you’ll no doubt experience faster growth and more abundant yields — if everything is done properly (and if it’s not, you’ll end up wasting a lot of money…)

Basically, a hydroponic system is a system that delivers all of the requisite mineral salt nutrients to the cannabis plants in water via the process of osmosis. Some experts prefer to do this manually and hand-select their own nutrients/minerals etc to add, but this takes a lot of time and a lot of experience.

If you really want to go hydroponic over traditional soil, there are several nice kits out there that are pretty straightforward and foolproof, but of course they’ll cost at least 10 times what you’d probably pay for a good, nutrient-rich soil.

Step 6: Choose a “Canna-tainer” (Container) to Grow Your Cannabis In

how to grow marijuana indoors

After you’ve decided whether to go with soil or hydroponics, you’ll then need to figure out what type of container to grow your cannabis in.

Of course, most of the time this will be predetermined with whatever system you choose to grow in (i.e. a lot of people just buy pots with pre-filled soil). You can indeed grow a few large plants out of a 5-gallon bucket (or some other regular household container), but be advised that cannabis plants do not like waterlogged conditions, so make sure to perforate the bottom of the bucket so the water can drain out as needed.

Also, there are some really good pre-filled soil kits out there that have been specifically designed for increased airflow (which is super important for growing high quality weed), so keep these in mind when deciding what to grow your first cannabis plants in.

Step 7: Show Your Cannabis Plants Some Love (By Giving them Lots of Nutrients)

cannabis harvesting

Other than a quality light source, knowing what kind of nutrient products, minerals, and other food materials to give your plants (and when to give them to them) is probably the single most important factor in growing high-quality cannabis.

Indeed, you’ll hear a lot of people say stuff like, “dude, it’s weed… just put it in some freaking soil and shine a light on it.” While there is indeed some truth to this (weed is incredibly hardy and resilient), keep in mind that your end goal is always robust, high-quality buds – and you won’t get these without the proper care and expertise (you think all those beautiful buds at marijuana dispensaries come from plants that are just “tossed in some soil?”).

In any regard, whether you’re growing in an organic soil mix or growing hydroponics, your cannabis plants will need what’s commonly referred to as the “super seven” macronutrients. In no particular order, these are: Nitrogen (N), Potassium (P), Calcium (Ca), Phosphorus (Ph), Magnesium (Mg) (not to be confused with Manganese, Mn), Iron (Fe), and Copper (Cu).

You can get these macronutrients pre-packaged in liquid or powder form (if you’re using an unsupplemented soil mix), but a lot of organic “super soils” will already contain them in sufficient amounts.

Lastly, it’s true that some strains require more calcium than others in order to produce robust, healthy nugs, so do a little research on the particular strain you’ll be growing in order to become more familiar with what kind of “food” it needs and prefers the most.

Step 8: Cannabis Plants LOVE Water!

harvesting hemp

A common assumption among rookie growers of any kind of plant is that the more you water them, the better.

While this is true to an extent, there absolutely is a thing as “too much water,” and overwatering your indoor cannabis plants can prove detrimental to their productivity, and could even out-and-out kill them!

How often you water your plants and how much you water them will ultimately be determined by obvious things like the size of the plant, and the stage of development that it’s in (i.e. cannabis plants in vegetative growth will not require as much watering as mature plants in the flowering stage). Really, though, there’s no exact science in terms of how much water you need to be giving them on a day to day basis.

A lot of people in fact only choose to water once the leaves start noticeably drooping, as over-saturated root systems, especially in cannabis plants, are very prone to fungal diseases.

Like we mentioned earlier, make sure that you’ve got holes drilled into your growing container so that the water can drain out, and when watering, try and only moisten the soil rather than full-on saturate it.

Lastly, most people will simply just fill up a jar or spray bottle from their tap, but be advised that this could do harm to the plants if there is too much chlorine in it or too many unfiltered minerals. Depending on the quality of your tap water, you may want to choose a distilled option or at least filter it out first before adding it to your soil. Believe it or not, mineral-laden tap water can cause unwanted buildup in the cannabis root systems, which can lead to detrimental root disease.

Step 9: Set Time to Care For Your Plant (Every Single Day!)

cultivating cannabis plants

As a DIY indoor grower, we realize that you’re likely not going to have the time to watch over your plants like a hawk and care for them 24 hours a day (this is, after all, why you’ve got your operation mostly set up on an automated system).

That being said, it really doesn’t take much at all to give your plants some quality “cannabis care.” Even if you’re the busiest person on earth and work 14 hours a day, you should be able to find a few minutes here and there to check on your operation each day and make sure things like temperature, humidity, pH, and water levels are sufficient.

Also, any quality indoor cannabis growing guide will tell you to watch out for male plants in your crop.

If you’re growing for high-THC buds, the only thing you want in your crop are female plants, with no mature male plants in the vicinity. If you’ve got a male in your crop and it reaches maturity to the point where its pollen sacs burst, it will pollinate the females – at which point they’ll start developing seeds rather than growing buds. While the plants themselves won’t actually die, they will effectively be ruined in terms of being able to produce consumable buds.

If you don’t know how to tell a male cannabis plant from a female, we’ve got a great article on the topic, so be sure and check that out when you get a chance.

Basically, if you’re growing from seed you won’t really be able to tell if you’ve got male plants or female until after the vegetative stage.

Once the plants start reaching maturity, they’ll start developing reproductive parts at the nodes, and this is when you can extract the male plants and get rid of them (or better yet, make them into something like a cannabis tea or smoothie). Male plants will have what look like little clusters of peas (these are the pollen sacs), while female plants will have sharper, pointer early-stage calyxes.

The likely scenario, however, is that you’ll be growing from female clones or pre-purchased feminized seeds, in which case you won’t really have to worry about males popping up in the crop. Still keep an eye out for males though even if you are using feminized seed, as they’ve been known to work their way into even some of the more reputable brands’ packages.

Lastly, we highly recommend doing some supplemental reading on how to grow marijuana indoors and outdoors, as our guide here is pretty basic in nature. Jorge Cervantes and Ed Rosenthal are pretty much the gurus when it comes to all things cannabis cultivation and growing, so check out some of their works if you want to vastly up your knowledge level.

Step 10: Cut Your Cannabis Plants Down — Carefully!

cannabis growers

After all is said and done and you’ve found a proper grow space, got your lighting system all set up, found a good container to grow in, and planted your seeds, the time will (hopefully) come when you can actually harvest the buds and put them to good use!

Granted, snipping a few buds off of one, two, or a handful of plants wouldn’t exactly be classified as “cannabis harvesting,” but still, there are some things you’ll want to know and understanding before you start your cannabis cuttings with a pair of scissors you pull from your kitchen junk drawer.

A lot of first time growers will assume that the nugs just pop out completely separately on the branch, and are simply plucked off, ground up, and smoked. However, there’s a little more to it than this.

Generally speaking the nice big nugs on a healthy, “pre-harvested” plant will be mixed in pretty well amidst a plethora of fan/water leaves and sugar leaves. In order to get at the nugs, you’ll have to do a fair bit of trimming and snipping away with a decent pair of scissors. This can actually be a pretty tedious and lengthy process, but trust us – after putting in all that work and effort into growing the plants, it’s a job that you’ll be more than happy to do. It’s actually super relaxing and enjoyable.

The first thing you’ll want to do when harvesting your plants is to cut off the big water leaves, otherwise known as the fan leaves. Even though these are the iconic “pot leaves,” they have very little THC in them and are generally just tossed out. (If you don’t want to trash them, however, there are a few things you can do with fan leaves so that you put the entire plant to good use).

Once you’ve got all the big fan leaves cut away, you’ll then be left with a hearty clump of nugs and sugar leaves. You’ll notice a visible difference between the long, green fan leaves and the smaller sugar leaves, as the latter will be covered in resinous glands (trichomes)… hence the appearance of ‘sugar.’

Some people don’t really bother snipping the sugar leaves away (they’ll just grind them up and smoke them along with the calyx/buds), but if you want to do the job right, you really need to trim the sugar leaves away so that you’re left with nothing but the nugs themselves (make sure to hold on to your sugar leaves and keep them in a separate pile, though, as they are full of THC and can be used to make hash, butter, wax etc).

Once you’re done with your trimming and have given the buds a nice “haircut,” you’re pretty much done! The only thing left to do at this point is to hang them to dry, which is actually an important process all in itself that we discuss in a separate article.

Also, be advised that the scissors you use will gunk up pretty nicely when doing your cannabis plant cuttings. This is completely normal, and you can actually scrape the “gunk” off and smoke it straightaway! This is known as “scissor hash,” and is actually super tasty and potent.

All in all, harvesting hemp and cannabis is a lovely experience, and it is one that we recommend to any weed lover who’s got a passion for all aspects of the plant. You learn so much about cannabis and about botany/biology in general, and in fact, there has not been a grow that’s gone by where we didn’t learn something entirely new about the whole process. There’s no doubt a bit of a learning curve involved – you’ll definitely make your fair share of mistakes – but trust us when we say that it’s all worth it in the end.

We hope this basic guide on how to grow cannabis indoors has been helpful in some way, and we hope that it’ll set you on the path to a fun and productive marijuana cultivating experience.

Enjoy, and more than anything else — remember to HAVE FUN!

3 comments
  1. David Westfall
    This has totally peaked my interest.

    Wow! This is a great article. I’ve read a lot of different write ups on this process and it was by far the best for application towards a quality growth. Thanks a million!!

  2. Brad

    This is the best explanation I have found for a first time grower. Thanks! Now can you give me some advice on what are the proper lights and where to find them? My room is 25 sq ft. You guys rock!

  3. hank
    lookin good!

    Seven weeks old and growing nicely!

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