How to Grow Cannabis Indoors: Beginner’s Guide


[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. We, therefore, advise that all readers become familiar with current laws and regulations in their region before they learn how to grow cannabis indoors].

As a potential first-time grower, getting started is the biggest roadblock you’ll likely face. First, you have to find the right place to cultivate and obtain the proper growing equipment. Then, you need to buy cannabis plants or seeds and spend a lot of time checking and maintaining your crop.

You must also operate within the boundaries of the law before getting started. Growing marijuana remains illegal in many U.S. states. Therefore, make sure that home cultivation is allowed where you live before proceeding. Assuming you are legally able to continue, keep reading our detailed guide to growing cannabis indoors.

Step 1: Choose the Perfect Cannabis Grow Room

You don’t need a particularly large growing/cultivating space. A typical grow room for a small-scale grower is a small tent, cabinet, or designated area in a spare room. If you’re stuck for room, even an unused corner of the house is sufficient! Here are a few helpful tips to get started.

cannabis grow

1 – Begin Growing from a Small Plot & Adjust as Necessary

By “small,” we mean nothing more than a few plants at most. You can start with just one or two plants. There is an inevitable learning curve involved with growing weed indoors. As such, you are bound to make some mistakes. The fewer plants you have, the fewer plants you’ll waste.

Even veteran cannabis growers run into mistakes and unexpected mishaps with almost every batch they produce. Therefore, it is possible to endure a completely failed grow on your very first attempt. In this case, it hurts a lot less when you ‘lose’ a plant or two.

how to grow marijuana

It shouldn’t take long to get the hang of things and start producing some beautiful, flowering cannabis plants. At this stage, you’ll need to make room as your marijuana proliferates. From the first signs of flowering, you can expect a plant to double or triple in size by harvest time.

Also, make sure that you leave enough space to work in!

2 – A Clean Space is One of the Most Important Things to Remember

Make sure that your cultivating space is sanitized and clean all around. There is an inherent risk posed by pests and contaminants. A messy space invites pathogens and harmful bacteria and mold. A good idea is to plan a bi-weekly cleaning routine and stick to it. There is no need to be pedantic, though! Using a wet microfiber rag to wipe up the areas around the plant(s) will suffice.

Marijuana plants are “bioaccumulators,” which means they “suck up” everything around them (both in the air and the soil). Make sure the area surrounding the plants is clean to keep potential contaminants out.

3 – Keep Your Grow Space as “Light-Sealed” as Possible

Light is essential for the growing process. Your plants receive direct light the majority of the time. However, few first-time growers realize that periodic darkness is equally as important for producing “yieldable” buds.

Like most living things, cannabis plants need their “rest time.” If light from a surrounding source is seeping in while it should be dark, the (bud-producing) females go into “survival mode.” This process causes them to produce male flowers, which ruins your chances of a high-THC yield.

4 – Successful Indoor Growing Requires the Following Features

  • Choose a secure place safe from any “unwanted visitors.” It keeps your plants away from animal and human invaders. It also enables you to monitor them regularly.
  • Temperature and humidity concerns will always remain an issue. Try and select a spot that is well sealed off from fresh air from outdoors.
  • Convenience is just as important as anything else. Therefore, make sure your spot is safe, and easily accessible at any time, day or night.

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

The light source you use in your grow room plays a significant role in determining the quality of the plants. We recommend spending a high degree of your budget on a good lighting setup. It is worth it in the end, particularly if you plan on growing in the long term.

cannabis plants

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

LED grow lights

If cost isn’t a consideration, LED (light-emitting diode) lighting is the preferred option for most marijuana growers. These are highly efficient light fixtures for indoor growing. They use little energy and create very little heat. Also, LEDs contain wavelengths across the light spectrum, so they can lead to bigger yields and better-quality plants.

The drawback is that they cost nearly ten times more than a decent HID setup! If you’re serious about getting into growing and have money to spend, however, give serious consideration to LEDs. Do your homework to avoid ‘scam’ LEDs online.

Induction grow lights

Induction lamps are an odd choice for indoor growers. However, some companies have recently adapted them for the cannabis industry. They can potentially represent decent value in terms of cost and efficiency.

growing marijuana

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

HID grow lights

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

The main drawback is that they require numerous accessories to run correctly. As a consequence, the overall cost can ramp up pretty quickly, depending on how much you’re willing to splurge.

For example, most growers use one of two main types of HID lamps/bulbs depending on the developmental stage. Metal halide (MH) bulbs are best during vegetative growth. High-Pressure Sodium (HPS) is the preferred option for the mature flowering stage. If you can only afford one, choose HPS as they are more efficient on a ‘watt-to-light’ produced scale.

HID lights produce a substantial amount of heat. Therefore, you must invest in a ballast and hood/reflector for each light. This is almost mandatory for controlling the temperature in your grow room. Connect the hood to your ventilation system to flush out excess heat and maintain an average ambient temperature.

Fluorescent grow lights

Fluorescent lights are generally much cheaper and easier to use than the other options. They represent an excellent option for those not planning long-term operations. They don’t require a connection to an external ventilation system. Fluorescent lights are a little less efficient than the other options. However, for novice DIY growers with a single plant or two, they’re likely your best bet.

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

Make sure you have consistent airflow across your entire plot. Depending on the size of your grow room, you can achieve this easily. All you need is a portable fan on one side of the space, and an exhaust fan on the other side facing the ceiling.

growing marijuana indoors

Since warmer air rises, the exhaust fan sucks out the hot, stagnant air. The portable fan provides an excellent supply of cooler, CO2-filled fresh air. This technique allows for a constant supply of fresh air for your plants. It also helps keep temperatures to a manageable level.

Most cannabis strains prefer an upper-temperature range between 70- and 85-degrees Fahrenheit. When the lights are off, keep room temperature between 55 and 75 degrees. Indica strains tend to prefer the cooler end of the range.

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

The next step is a self-monitoring system to control it all. We assume you can’t spend 24 hours a day in your grow space! You need a 24-hour timer and an adjustable thermostat. The latter allows you to set your exhaust fan to switch on once temperatures go above a certain degree. The result is a relatively stable temperature range and humidity level while saving energy and money.

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

We also recommend investing in a pH meter to check on the quality of your water and soil regularly. If you’re growing in soil, try and keep the pH between 6 and 7. If you’re growing hydroponically, 5.5 to 6.5 is an appropriate range.

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

When cultivating cannabis indoors, there are two viable options: Growing in traditional soil or a hydroponic tray. Soil is typically recommended if you’re growing indoors for the first time. It is cheaper, more straightforward, and more forgiving than an advanced hydroponic system. Let’s take a closer look at each of the two options.

how to grow weed indoors

Soil vs. Soilless Growing

Soil is less expensive, easier, and offers a higher margin of error. However, you need to carefully select the soil because the quality can vary enormously. General potting soil works when you periodically add nutrients. However, pre-fertilized soil is a better option because it removes most of the guesswork from the equation. High-quality soil of this nature requires minimal maintenance.

All you need is a quality soil with a proper nutrient-rich, optimized growing mix. Ideal ingredients include bat guano and mycorrhizae bacteria, as well as other organic compost nutrients.

The “all-in-one” automated hydroponic setups may help you experience faster growth and more abundant yields. Alas, this is only the case if everything is done correctly. If not, you waste a LOT of money!

A hydroponic system delivers all necessary mineral salt nutrients to plants in water via the process of osmosis. Some experts prefer to do this manually and hand-select their nutrients/minerals. However, this takes time and a lot of experience.

If you want to choose hydroponic over traditional soil, there are several excellent kits that are straightforward and foolproof. On the downside, they’ll cost at least ten times what you’d probably pay for good, nutrient-rich soil.

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

If you purchase nutrient-rich soil in pots, you’ll already have the containers you need. You can also grow plants out of a 5-gallon bucket or another regular household container. However, cannabis plants don’t like waterlogged conditions. Make sure to perforate the bottom of the bucket so the water can drain as needed.

how to grow marijuana indoors

There are some outstanding pre-filled soil kits specially designed for increased airflow. 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)

Ensuring your plants get the right nutrients is probably second only to lighting in terms of importance. Proper nutrient selection and application are among the most critical factors in growing premium-grade cannabis. While weed is resilient, growing it in sub-optimal conditions means you will miss out on yield and potency.

Whether you’re using an organic soil mix or growing hydroponically, your cannabis plants need the “super seven” macronutrients. In no particular order, these are:

  • Nitrogen (N)
  • Potassium (P)
  • Calcium (Ca)
  • Phosphorus (Ph)
  • Magnesium (Mg)
  • Iron (Fe)
  • Copper (Cu)

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

cannabis harvesting

Lastly, some strains indeed require more calcium than others to produce robust, healthy nugs. Perform a little research on the particular strain you are growing. This process enables you to become more familiar with the kind of “food” it needs and prefers the most.

Step 8: Cannabis Plants LOVE Water!

A common assumption amongst rookie plant growers is that the more you water, the better.

While this is true to an extent, there is such a thing as “too much water.” Overwatering your indoor cannabis plants can prove detrimental to their productivity, and potentially kill them!

The frequency of watering and the amount you give is determined by a few obvious things. These include the size of the plant and the stage of development that it’s in. For example, cannabis plants in vegetative growth don’t require as much watering as mature plants in the flowering stage. However, there’s no exact science when deciding how much water to give and how often.

harvesting hemp

For instance, lots of people only choose to water once the leaves start noticeably drooping. After all, over-saturated root systems, especially in cannabis plants, are prone to fungal diseases.

Make sure there are holes drilled into your growing container so the water can drain out. When watering, try, and only moisten the soil rather than saturating it.

Lastly, many growers fill up a jar or spray bottle from their tap. Bear in mind that this could harm the plants if there is too much chlorine or unfiltered minerals in it. You may want to choose a distilled option or at least filter it before adding it to your soil. Mineral-laden tap water can cause unwanted build-up in the cannabis root systems, which can lead to detrimental root disease.

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

DIY indoor growers are unable to perform a 24/7 watch over their plants. However, you can provide adequate care by setting aside a few minutes a day. Routine checks, such as ensuring things like temperature, humidity, pH, and water levels are correct, are essential.

cultivating cannabis plants

Also, watch out for male plants in your crop. If you wish to grow high-THC buds, the only thing you want in your crop is female plants. If you have a male in your crop, it could cause problems. Once it reaches maturity and its pollen sacs burst, it fertilizes the females. At this point, they’ll start developing seeds rather than growing buds. While the plants won’t die, their ability to produce high-THC buds is ruined.

If you don’t know how to tell a male cannabis plant from a female, we’ve got a great article on the topic.

grow indoors weed

If you’re growing from seed, you need to wait until the vegetative stage. Once the plants start reaching maturity, they’ll develop reproductive parts at the nodes.

This is when you can extract the male plants and eliminate them. Male plants will have what look like little clusters of peas; these are the pollen sacs. Female plants will have sharper early-stage calyxes. Those growing from female clones or pre-purchased feminized seeds should have no concerns about male plants.

Step 10: Cut Your Cannabis Plants Down — Carefully!

The final step involves harvesting your plants. A lot of first-time growers assume that the nugs pop out separately on the branch. Then, they can pluck them off, grind them up, and start smoking. It is a little more complicated!

The nugs on a healthy, “pre-harvested” plant are mixed with a plethora of fan/water leaves and sugar leaves. You need to use scissors to trim this foliage to get to the nugs. Once you get used to the process, you’ll find it more enjoyable than tedious.

cannabis growers

The first step is to cut off the big water leaves, otherwise known as the fan leaves. They have minimal THC in them and are generally removed. Sugar leaves and buds should remain. You’ll notice a visible difference between the long, green fan leaves and the smaller sugar leaves. The latter is covered in resinous glands (trichomes).

Some people like to grind the sugar leaves and use them. However, it is all about the nugs if the goal is to enjoy an intoxicating high. You can use the sugar leaves to make cannabutter, however. After trimming, you should hang the buds up to dry. After 7-10 days, you can place them in airtight containers to cure. The more patient you are, the better the buds will taste. They are also more potent!

Final Thoughts on Growing Cannabis Indoors

Harvesting hemp and cannabis is a lovely experience. It is one we recommend to any weed lover who has a passion for all aspects of the plant. You learn so much about cannabis and botany/biology in general. Most growers believe they learn something new with every harvest.

There’s no doubt a bit of a learning curve involved. You’ll make your fair share of mistakes. However, trust us when we say it’s all worth it in the end.

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