A Beginner’s Guide to Indoor Cannabis Growing – Part 1 we looked at how you can start your own indoor grow. We covered what kind of grow room or space is needed. How important cleanliness is and what sort of lights are used for the vegetative and flowering stages of your grow. Things are getting exciting now. Next, we are going to cover some important factors that will get you smoking your own home-grown bud in no time!
Give Your Plants Air
Cannabis plants are no different to other plants in that they need fresh air to thrive and CO2 for photosynthesis. This means you need a steady stream of air flowing through your grow room. The best way to achieve this is by placing an exhaust fan near the top of the room to remove any warm air. On the opposite side of the room, near the floor, place an air inlet fan with a filter. This is to pull fresh clean air into your room. By having an inlet and outlet fan you will keep the air in your room fresh and circulating. This is very important to ensure that temperatures remain in a comfortable range.
When your lights are on, temperatures should be between 20 degrees C and 30 degrees C and between 15 degrees C and 20 degrees C when the lights are off. Some varieties of cannabis (usually Indica’s) prefer the lower side of the range. While some others are more tolerant of higher temperatures.
Exhaust Fans for Airflow
The size of your exhaust fan will depend on the size of your grow room and the amount of heat that is being generated by your lighting system. HID systems put out loads of heat, especially if they are not mounted in air-cooled hoods. Some growers that live in warmer regions will often run their lights at night. This is in an attempt to keep temperatures in their grow room down.
Its recommended that you set up your lights, turn them on for a while. Then determine how much airflow you will need to maintain a comfortable temperature for your plants. This will allow you to choose an exhaust fan that is suitable for your needs. If the smell of flowering cannabis plants may cause you problems, try adding a charcoal filter to your exhaust fan.
It is possible to create a sealed artificial environment by using an air conditioner, dehumidifier, and supplemental CO2 system. However, this can be very expensive and not recommended for the first-time grower.
Finally, it is a good idea to have a constant light breeze in your room. This will strengthen your plants’ stems and creates a less hospitable environment for mold and flying pests. A wall-mounted circulating fan works well for this purpose. Just don’t point it directly at your plants because it can cause windburn and hurt your babies.
Controls and Monitoring
Ok, so now that you have chosen your lights and climate control equipment. You will want to automate their functions to make things easier. There are sophisticated (and very expensive) units available that can control lights, temperature, humidity, and CO2 levels. All that you will need as a beginner grower is a simple 24-hour timer for the lights and an adjustable thermostat switch for the exhaust fan.
The light cycle of your cannabis crop is one of the most important growth factors you need to consider. The timing of the light/dark period is very important when growing cannabis. For germination, the lights can be left on for 24 hours to help speed up this first stage. After the plants have sprouted and begun their vegetative growth, you can then turn the lights on for 16-20 hours per 24-hour period until they reach maturity and are ready to flower.
When the plants are ready to produce bud you then will need to turn the lights on for less than 12 hours in a 24-hour period. The reason a timer is important is your lights need to turn on and off at the same time every day or you risk stressing your plants. You can also use a timer for your exhaust fan. However, spending a few extra bucks on a thermostat switch is a much better option.
The most basic models, you simply set the thermostat on the device to the maximum desired temperature and plug your exhaust fan into it. Once the temperature rises to the level you set, it will turn the fan on. When the temperature drops a few degrees below the set threshold it will turn off. This will save you energy and maintain a steady temperature.
Since you won’t be in your grow room all the time. A combination of hydrometer/thermostat with high/low memory feature can be a very handy device to keep tabs on things in your room. This little gadget is small and inexpensive and will show you the current temperature and humidity level. It will also show the highest and lowest reading since you last checked.
Another good idea is to keep a PH meter or test kit on hand. This is so you can check the PH level of your water, nutrient solution, or soil. Cannabis prefers a PH between 6 and 7 in soil and between 5.5 and 6.5 in hydroponic media. If the PH gets out of this range it can lead to a nutrient lockout. Meaning your plants are unable to absorb the nutrients they need. Be sure to test your water and soil regularly. Also, make sure that the PH of the nutrient mix you feeding your plants falls in this range.
Choose a Grow Medium
Another great advantage of growing indoors is you have many different growing mediums to choose from. It can be good old-fashioned pots filled with soil or a rockwool slab in a hydroponic tray, every option has its own pros and cons. We will examine the two most popular methods and mediums that are used today.
The soil is by far the most common and the most forgiving medium used to grow cannabis. This is a good choice for first-time growers and any high-quality potting soil will work fine. Choose a soil that does not contain any artificial extended release fertilizer, this is unsuitable for growing good cannabis.
A very good choice for beginners is organic pre-fertilized soil, that if used correctly can grow cannabis plants from start to finish without any added nutrients. This can be made yourself by combining worm castings, bat guano, and other components with a good soil and leaving it to sit for a few weeks. If you don’t have the time to make your own, then it can be purchased pre-made from a few different suppliers.
As with all organic growing, this method relies on a healthy population of mycorrhizae and soil bacteria to facilitate the conversion of organic matter into nutrients. Another option is to use regular soil mix and then supplement your plants with liquid nutrients as the soil is depleted.
Indoor growers are increasingly turning to soilless, hydroponic systems for growing cannabis plants. This method requires feeding with concentrated solutions of mineral salt nutrients that are absorbed directly through the process of osmosis. This technique allows for faster nutrient uptake that leads to faster growth and bigger yields. This method is for more experienced growers as plants are quicker to react to under or overfeeding and can easily get nutrient burn or lockout.
Different materials used include rockwool, vermiculite, expanded clay pebbles, perlite and coco coir, to mention a few. Commercial soilless mixes are widely available and combine 2 or more of these mediums to create an optimized growing mix. Soilless mediums can be used in automated hydroponic setups or in hand-watered individual containers.
Indoor Cannabis Growing Part 3 to follow…
We are now even closer to giving you all the knowledge you will need to grow a successful crop, at home! I hope you feel that much more confident in your knowledge to grow cannabis. Follow our guide and you will have all the tools in your arsenal to show off your growth potential. In our next and final post, we will determine what to grow your cannabis in. What type of nutrients to feed your plants and the importance of a watering schedule.
Remember, growing cannabis is a labor of love so spend a lot of time with your plants and have fun!
Written, November 2018
~ Medical Cannabis Seed Bank