A beginner’s guide to growing cannabis indoors

By Stoney Tark

Investing in grow lights

The choice of high end grow light ranges from basic fluorescents to high end LED lights. Many horticultural lighting manufacturers have mastered the perfect spectrum, and are able to calculate the efficacy of the grow lamp unit per joule. Not all grow lights are up to the job and depending on if you are growing under 18/6 or flowering under 12/12, the lighting spectrum may differ. If you want to achieve buds with a thick density, then you need to invest in a H.I.D light (High Intensity Discharge) or an LED. Avoid Chinese made LED as these can be outdated and seriously lacking when it comes to performance. I would personally recommend using SANlight which are a company based in Austria, which make excellent grow lights. When you are installing your grow light, it is wise to use a spirit level and check the light is shining evenly. Hanging lights correctly is very important and ensuring the light distribution is evenly spread will be a big player in how the canopy grows.

• Lighting spectrum will dictate the growth of your Cannabis plants
• Some LED grow lights have incredible technology built in
• Growing with H.I.D lighting does require a ballast to power up
• Fluorescents (C.F.L) are great for clones and seedlings
• Use metal S hooks if hanging LED lights to ensure a secure hanging
• LED lights use far less electricity and also have an enhanced spectrum
• Lumens refer to the measurement of light to the human eye and not plants.

The grow tent

The grow tent is where you will keep your Cannabis plants inside growing safely and securely. Fitted with an extraction kit that will keep the air being blown out Carbon fresh, the other purpose of the tent is to reflect light and to also prevent any light entering or exiting.

Pretty useful when the name of the game is discretion, so a grow tent is where all the magic happens. Tents are available in all shapes and sizes starting from small sized for clones and young plants, to commercial popularised bedroom units such as 1m, 1.2, 1.5 or 2m squared. Large grow operations may be able to house a tent that is much larger than 2m, however for beginner growers, it is wise to start small and understand the mechanics of how everything functions from the equipment to the cannabis plants.

The extraction kit

Extraction Fan: This is basically the larger sized fan that is used inside the top of the tent to blow air out. By doing this, there will be a negative drag created which is where the air flow will be generated from. How much air should actually be recycled every hour depends on the capacity of the fan in question, as well as the size of the grow tent.

R.V.K are generally loud but certainly do the job. Inside a tent of 1-1.2m squared, it is advised to use an extraction fan that is 125mm fitting and will usually remove 220M3/Hour of air. This fan will then be directly fitted to a carbon filter which will then suck air from inside the tent, through the carbon and be exhausted outside of the tent.

Aluminium ducting is how the carbon filter and exhaust fan will connect, meaning that there will be one tube of ducting connecting one end of the carbon filter to the R.V.K and the other end of the R.V.K exiting the tent where the exhausted air can be removed from the garden and recycled with new fresh air from the intake fan situated at the bottom of the tent.

In-line fan

This is where the fresh air will enter the lower parts of the grow tent. We know that warm rises and cold air stays low, so bearing this in mind you will get an idea of how quickly the fresh air is disputed around the tent and exhausted out. The output of your inline fan will be much lower than the performance of the R.V.K, as this will encourage the tent to be in a state of negative drag.

I personally like to use T.T fans for the role of the intake. These fans are easy to connect, silent and will last a long time before needing replacing. How the fresh air from the intake is blown around will be down to oscillating fans, located at different parts of the tent. Some growers choose to use clip on fans, floor fans or wall fans. Staying on top of the air flow inside the grow tent will have many benefits ranging from cooler temperatures, more carbon dioxide being blown around the plants, preventing airborne pathogens and plant disease from settling.

• Use strong tape to connect the ducting to the carbon filter and R.V.K fan
• Your R.V.K and carbon filter should run 24/7 and never be shut down at night
• The size of the ducting must match the fitting of the R.V.K and carbon filter.
• Never let ducting droop or have excessive amounts of ducting
• Different fans have a different output so always double check
• Your extraction kit will need to hang in the top 30-60cm of the grow tent.
• Try to connect the ducting connected to the T.T fan at an open window
• The smallest size available for T.T fans is 100mm fitting.

Selecting a growing medium

Traditionally growing Cannabis in soil and hand feeding only water has been the most popular way, however there are many different growing mediums available now, and different nutrients also. Some substrates have been made to hold water, as others have been created to retain.

When choosing a growing medium and pot size, you should consider the size of the Cannabis plants you want to grow. Growing mediums generally cover two parts, soil and soil less mediums. These refer to inert pH neutral substrates such as coco, perlite, vermiculite, hydroton clay balls and rockwool. These are all suited for hydroponic culture which actually requires roots to grow freely without the restriction of an organic medium. Customising your growing medium to get the best qualities of each substrate is a wise move. Mixing coco, worm castings, perlite and hydroton will create an airy, light mix that is full of air pockets and has excellent water retention and promotes roots to grow quickly.

• Fabric pots allow roots to breath and become air pruned at the same time.
• Plastic pots will cause Cannabis plants to become root bound
• It is better to use hydroponics with inert growing mediums
• Soil culture uses beneficial bacteria and fungi deep within the soil
• It is better to have a growing medium that can easily dry and air out
• Hydroponic nutrients are used by Cannabis plants differently to organics

Lighting times and different cycles

Once you have set up your grow tent and then securely hung up your extraction kit and placed the fans where they need to be and filled your pots, next you need to set your timer. There are two cycles that the plant will go through before it can be harvested. 

The vegetative stage

This is where the plants will think it is Summer time, where the days are long and the air is heavy with humidity. The temperature inside the grow room should be 24 degrees Celsius in the daytime with a nighttime decrease to 18 degrees Celsius.

Relative humidity needs to be in the 70% mark for the entire duration of the vegetative stage and this is where the timer will be set to 18 hours of light and 6 hours of total darkness. The way to get an accurate reading of the temperature and humidity together, is by using a hydrometer. These are inexpensive and usually come with a sensor to allow you to take a reading from any point in the grow tent. The hydrometer will also indicate the relative humidity levels present inside the tent and how close or far away you are from the 70% humidity range.

• Humidifiers do an excellent job of maintaining consistent humidity levels
• Supplementing the garden with CO₂ is possible during 18/6
• Dry conditions will cause plants to over transpire and slow down growth
• Foliar spraying your plants will help keep them happy during the veg stage
• Never spray the sensor of the hydrometer and always be aware of where it is CO₂ should only be used when temperatures exceed 30 degrees Celsius

The flowering stage

Here is where the days will become shorter for the plant and the timers will be set to 12 hours on and 12 hours off. Temperatures should be 24 degrees Celsius, however you will need to change the relative humidity to 30%. It is very important Cannabis plants recieve dry conditions and that humidity never creeps past 40%, especially with poor air circulation.

• Use a dehumidifier to pull excess water out of the tent if necessary
• The hydrometer will give a clear indication of the environment
• Keep all oscillating fans during night times to keep air movement consistent
• Running your lights at night can allow a grower to pull in cooler temperature

Sound proofing the garden

Keeping your indoor garden well hidden from neighbours and the authorities should be at the top of your priority list. The level of noise that exhaust fans can make can be really loud and cause constant anxiety in the home. Soundproofing your grow room is always advantageous and can be easily done.

• Use acoustic ducting to reduce the noise made by the air passing through
• Invest in a custom sized acoustic box that will house the noisy R.V.K fan
• Silencers attached to either end of an R.V.K fans drastically reduce the noise
• Hang your extraction unit so there are no vibrations passing through the tent
• Fan speed controllers are really great for lowering the sound of loud R.V.K fans