How to Grow Cannabis Indoors: A Guide to Getting Started

Come coltivare Cannabis Indoor: una guida per iniziare

How to Grow Cannabis Indoors: A Guide to Getting Started

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Congratulations, you are interested in growing your own cannabis plants for the first time! But before you raise that green thumb of yours, you need to understand that growing marijuana indoors presents its own set of challenges for beginners, and the sheer amount of information available on the topic can be overwhelming. Here we've looked at the pros and cons of indoor and outdoor , take a look before you get started! ;)

Our guide to growing cannabis indoors will help simplify the process with clear, easy-to-digest sections designed to give the novice grower a helping hand.

Step 1: Identify a 'Room' or Grow Space for Cannabis

The first step in starting your personal cannabis cultivation is to create a suitable space in which to do it. The space doesn't have to be your typical grow "room"; it could be a closet, a curtain, a piece of furniture, a guest room or a corner of an unfinished basement. Just keep in mind that you'll need to choose equipment (and plants) based on available space.

Start Small…

When tackling your first growing project, you need to start small for several reasons:

  • The smaller the grow, the less expensive it will be to set up
  • It is much easier to control a few plants than many
  • Your mistakes as a novice grower will be less harmful

Remember, most new cannabis growers will encounter obstacles along the way and lose plants to pests or diseases. A failure to grow a couple of plants will cost you less than a failure to grow 15 plants.

…But Think Big

When designing your space, you need to take into consideration not only the amount of space your plants will need, but also lights, air ducts, fans and other tools, as well as whether you need to give yourself enough space free to work. Cannabis plants can double or even triple in size at the start of flowering, so make sure you have enough room for tall growth!

If your grow room is a cabinet, tent, or closet, you can simply open it and remove the plants to work with; otherwise, you'll want to make sure you leave yourself some wiggle room.

Cleanliness is Crucial

Make sure your space is easy to sterilize; Cleanliness is important when growing indoors, so easy to clean surfaces are a must. Carpet, curtains and rough wood are all difficult to clean, so avoid these materials if possible.

Make sure it is Lightproof

Another crucial criterion for a grow room is that it is light-proof. Light leaks during dark periods will confuse your plants and cause them to produce male flowers.

Other Variables

When deciding where to grow your cannabis, keep the following variables in mind:

  • Convenience . You will need to monitor your plants carefully. Checking them every day is important, and beginners will want to check several times a day until everything is taken care of. If your room is difficult to access, this crucial step will be difficult.
  • Temperature and Humidity Issues . If your grow space is already very hot or very humid, you will have trouble controlling the growing environment. It is recommended to choose a cool, dry area with easy access to fresh air from outside.
  • Discretion . You'll probably want to keep your grow safe from nosy neighbors and potential thieves, so be sure to choose a location where noisy fans won't gain any unwanted attention.

Step 2: Choose your Cannabis Grow Lights

The quality of light in your grow room will be the deciding environmental factor in the quality and quantity of your cannabis crops, so it's a good idea to choose the best light setup you can afford. Here we present you a brief summary of the most popular types of cannabis grow lights used for indoor cultivation.

HID Grow Lights

HID (high intensity discharge) lights are the standard in the industry, used widely for their combination of output, efficiency and value. They cost a little more than incandescent or fluorescent fixtures, but produce much more light per unit of electricity used. However, they are not as efficient as LED lights, but cost a tenth in comparison, per unit.

The two main types of HID lights used for growing are:

  • Metal halide (MH, metal halide), which produces a bluish light and is generally used during plant growth
  • High pressure sodium (HPS), which produces light more towards the red-orange part of the spectrum, and is used during the flowering stages

Along with bulbs, HID light systems also need a ballast and a hood/reflector for each light. Some ballasts are designed to be used with MH or HPD lamps, while some newer ones will work with both.

If you can't afford both MH and HPS bulbs, start with HPS, because they provide more light per watt. Magnetic ballasts are cheaper than digital ballasts, but they run hotter, are less efficient and harder on bulbs. Digital power supplies are generally a better option, but are more expensive. Be careful with cheap digital power supplies, as they are often not well shielded and can create electromagnetic interference that will affect radio and WiFi signals.

Unless you're growing in a large, open space with lots of ventilation, you'll need reflective hoods that cool the air under which to mount the lamps, because HID bulbs produce a lot of heat. This requires air exchange ducts, which will increase your initial cost but make controlling the temperature in your grow room much easier.

Fluorescent Grow Lights

Fluorescent lighting systems, particularly those that use high-output (HO), are quite popular among small-scale growers for the following reasons:

  • They tend to be less expensive to install, because the reflector, ballast and bulbs are included in one package
  • They do not require a cooling system because they do not generate as much heat as HIDs

The main downside is that fluorescent lights are less efficient, generating about 20-30% less per watt of electricity used. And space is another issue, because to get the output of a single 600 watt HPS bulb, you would need about four 30cm T5 HO bulbs.

LED Grow Lights

LED (light emitting diode) technology has been around for a while, but only recently has it been adapted to create super-efficient lighting systems for indoor growing. The main disadvantage with LED grow lights is their cost: well-made systems can cost up to 10 times more than HID ones. The benefits are that LEDs last much longer, use much less electricity, create less heat, and the better ones generate a fuller spectrum of light, which can lead to larger yields and better quality.

Unfortunately, there are a lot of subpar LED lights made that are sold to growers, so do some research and read product reviews before giving away your hard-earned money.

Induction Grow Lights

Induction lamps, also known as electrodeless fluorescent lamps, are another older technology that has recently been adapted to meet the needs of indoor growers. Invented by Nikola Tesla in the late 19th century, the induction lamp is essentially a more efficient and long-lasting version of the fluorescent light bulb. The main disadvantages with these implants are their price and availability.

Step 3: Air your Cannabis Plants

Plants need fresh air to thrive, and carbon dioxide (CO2) is essential in the process of photosynthesis. This means you will need a constant flow of air flowing through your grow room, which is easily achieved by having an exhaust fan placed near the room's ceiling to remove the hottest air, and an inlet of air filtered from the opposite side, near the floor.

You will need to ensure that the temperature remains in an appropriate range for your plants, between 20 and 30°C when the lights are on, and between 15 and 20°C when they are off. Some cannabis strains (generally sativa strains) prefer the lower end of the range, while others tolerate higher temperatures better.

The size of your exhaust fan will depend on the size of your grow space and the amount of heat generated by your lighting system. HID systems produce a lot of heat, especially if they don't have hoods to cool the air. People who live in warmer regions often leave lights on at night to try to keep their grow temperatures low.

It's a good idea to set up the lights, leave them on for a while, and then determine how much airflow you need to maintain a comfortable temperature for your plants. This will allow you to choose an exhaust fan that suits your needs. If the smell of flowering cannabis plants causes you problems, add a carbon filter to your exhaust fan.

Alternatively, you can create a sealed artificial environment using an air conditioner, dehumidifier and additional CO2 system, but this is quite expensive and not recommended for the novice grower.

Finally, it's a good idea to have a constant light breeze in your grow room, because it strengthens plant stems and creates a less hospitable environment for mold and flying pests. A well-fitted circulation fan works well for this purpose – but don't point it directly at the plants, as this could cause wind damage.

Step 4: Choose your Controls and How to Monitor

Once you've selected your lights and climate control equipment, you'll want to automate their functions. While sophisticated (and expensive) units are available to control lights, temperature, humidity and CO2 levels, the beginner will generally need a simple 24-hour timer for the lights, and an adjustable switch thermostat for the exhaust fan.

The timing of the light/dark cycle is very important when growing cannabis; in general, you will need to keep the lights on for 16-20 hours a day while the plants are in vegetative growth, and then switch to 12 hours of light a day when you want them to flower. You need the lights to turn on and off at the same time every day, or you risk stressing the plants, so a timer is essential. You can use a timer for your exhaust fan too, but spending a few extra dollars on a thermostat is a much better option.

With the most basic models, you simply set the thermostat to the desired maximum temperature for your space and connect the exhaust fan to it. Once the temperature reaches the level you set, it will turn on the fan until the temperature drops a few degrees below the threshold you set. This way you will save energy and maintain a stable temperature.

Since you probably won't be spending the majority of your time in your grow space, a hygrometer/thermostat combo with high/low memory option can be very useful to keep an eye on the conditions in your room. These small, inexpensive tools not only show you the current temperature and humidity level, but also the highest and lowest readings for the period of time since you last checked.

Another good idea is to keep a pH meter or test kit on hand, so you can check the pH level of your water, nutrient solution or soil. Cannabis prefers a pH between 6 and 7 in soil, between 5.5 and 6.5 in hydroponic media. Letting the pH get out of this range can lead to “nutrient lockout”, meaning your plants will not be able to absorb the nutrients they need, so make sure you check your water and soil regularly, and that the mix of nutrients you you are giving your plants falls within the desired range.

Step 5: Decide on a Medium for Growing Cannabis

Growing indoors means you have several methods to choose from, and whether it's pots filled with soil the old fashioned way, or a slab of rockwool in a hydroponic cart, each medium has its benefits and drawbacks . Here we will look at the two most popular methods and the medium they use.


Soil is the most traditional medium for growing cannabis indoors, as well as the most forgiving, making it a good choice for novice growers. Any high-quality potting soil will do, as long as it doesn't contain an artificial time-release fertilizer, which isn't suitable for growing good cannabis.

A very good choice for beginners is pre-fertilized organic potting soil (also often called super potting soil), which can grow Cannabis plants from start to finish without adding nutrients, if used correctly. You can do it yourself by combining vermicompost, bat guano and other components with good potting soil, then leaving it to sit for a few weeks, or you can buy it already made in various stores.

As with all organic farming, this method relies on a healthy population of mycorrhizae and soil bacteria to facilitate the conversion of organic matter into nutrients that are usable by the plant. Alternatively, you can use a regular potting mix and then give your plants liquid nutrients when the soil runs out of them.

Soilless (aka Hydroponics)

Indoor growers are all turning to the soilless, hydroponic medium for growing Cannabis plants. This method requires providing nutrition through concentrated solutions of mineral salts, which are absorbed directly by the roots via osmosis. This technique allows plants to be fed more quickly, which leads to greater growth and yield, but it also requires greater precision, because plants react more quickly if they are fed too much or too little, and are more susceptible to burning or shutting down. of nutrients.

Different materials used include rock wool, vermiculite, clay pebbles, perlite and coir, to name a few. Commercial soil-free mixes are widely available, and combine two or three of these mediums to create a mix for optimal growth. Soilless media can be used in automated hydroponic set-ups or in individual hand-watered containers.

Step 6: Determine What to Grow Your Cannabis in

The type of container you use will depend on the medium, system and size of your plants. A cart-style system with watering and draining might need small mesh pots with clay pebbles, or just a slab of rock wool on which to grow lots of seedlings, while a “super-soil” grow might have need 40L plastic pots to grow some big plants.

Inexpensive options include single-use perforated plastic bags or fabric bags, while others choose to spend more on “smart pots,” containers designed to improve airflow in the root zone of plants. Many people grow their first cannabis plants in 20L buckets. The most important thing is drainage though, because Cannabis plants are very sensitive to waterlogged situations, so if you want to reuse other containers, make sure you poke holes in the bottom and place them on trays.

Step 7: Give your Cannabis Plants Nutrients

Growing high-quality cannabis flowers requires more fertilizers, or nutrients, than most regular crops. Your plant needs the following primary nutrients (collectively known as macronutrients, which we've made a guide to here ):

  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)

These micronutrients are also needed, but in much smaller quantities:

  • Soccer
  • Magnesium
  • Iron
  • Copper

If you are not using a pre-fertilized organic potting mix, you will need to feed your plants at least once a week, using an appropriate nutrient solution. These nutrients are sold either as concentrated liquids or powders, to be mixed with water, and are generally formulated for either vegetative growth or flowering. This is because Cannabis needs several nutrients during its life cycle: it needs more nitrogen during vegetative growth, and more phosphorus and potassium during bud production.

Most macronutrients are sold in two-part liquid form, to prevent some elements from precipitating (combining with an inert solid that is unusable for the plant), which means you will have to buy two bottles (part A and part B) for vegetative stage, and two grow bottles, along with a micronutrient bottle. Aside from these basics, the only other product you may need to buy is a Cal/Mag supplement, because some strains require more calcium and magnesium than others.

Once you have purchased all the necessary nutrient products, simply mix them with water as directed on the label and water the plants with this solution. You should always start with half of what is recommended, because Cannabis plants burn easily. It is almost always worse to give your plants too much nutrients than less, and over time you will learn to "read" the plants, looking for signs of deficiencies or excesses.

Step 8: Water your Cannabis Plants

Most people don't think twice about the water they use to water their plants; If you can drink it, surely it will be fine, right? Well, it may not always be a problem, depending on where you are, but some waters contain a high concentration of dissolved minerals that can build up in the root zone and change nutrient intake, or they may contain fungi or other pathogens that they don't hurt people, but can lead to disease in the roots.

Additionally, some places may have high levels of chlorine in their water supplies, which could be harmful to some beneficial soil microbes. For these reasons, many people choose to filter the water they use in the garden.

The most important thing to remember at this stage is not to water too much. Cannabis plants are very susceptible to fungal root diseases when they are too wet, and overwatering is one of the most common mistakes made by novice growers. How often to water your plants will depend on the medium you use, the size of the plants, and the temperature of the environment. Some wait until the lower leaves of the plant begin to bend slightly before watering.

As you gain experience and knowledge, you will modify your grow room and equipment to better suit your particular environment, the growing techniques you use, and the specific strains you choose, but hopefully this article will provide you with some solid foundations of knowledge to start off on the right foot. And, remember, growing Marijuana is a labor of love, so spend lots of time with your plants and have fun!

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