How to set up a cannabis grow room

If you are thinking of growing indoors without a grow tent, either because you want to make your own or because you want to grow directly in a room, this guide will interest you. In our online grow shop we tell you everything in detail.

Chart of Contents:

1. Choose the area we want to use for cultivation
2. How do I calculate the number of plants I can put in a grow room?
3. Fabrication of a tent structure for home growing tent
4. Necessary material to grow cannabis plants indoors
5. Buy indoor growing equipment
6. Lining walls with reflective Mylar paper
7. Lighting for indoor growing
8. Types of grow lights
9. How to calculate lamp wattage?
10. Installation of an extractor air fan
11. How to calculate the power of a crop extractor air?
12. Intractor installation of crop air
13. Connecting tube for exhaust air evacuation
14. Installation of an activated carbon filter
15. Measuring temperature and humidity with a digital thermo-hygrometer
16. Installation of a light timer
17. Light parameters for indoor culture
18. Humidity control in indoor culture
19. The size of the pots
20. High Quality Cannabis Seeds

Choose the area we want to use for cultivation

To start making our own home grow tent, the first thing to do is to choose or select the surface area we want to use. That is, depending on the number of plants we want to grow, we will use more or less space. Once we know the number of plants we want to grow, we can start building the structure of the tent or grow room.

Let’s put ourselves in the situation that we want to grow 20 plants, but we have a room of 10m2, the ideal is to make a structure to reduce the surface area, in this way we will take more advantage of the light from the bulbs and it will be easier to maintain the temperature and humidity necessary for the crop.

How do I calculate the number of plants I can put in a grow room?

When we want to calculate the number of plants we can grow in a marijuana crop, we must ask ourselves two questions. Firstly, whether we are going to grow marijuana cuttings or seeds and secondly, the size of the pot we are going to use.

If growing from seed, our advice is to use 11 litre pots. This way you can ideally grow up to 7 plants per square metre.

If you grow cuttings, our advice is to use 7 litre pots. This way we can grow up to 14 plants per square metre.

So, let’s take the example that I have a room of 10 square metres and I want to grow seeds in 11 litre pots. Then we make the following calculation: 7 plants x 10 m2 = 70 plants, this calculation is approximate, remember that we must leave space to be able to access all the plants easily, for watering and so on.

Now let’s take the example of growing cuttings in 7 litre pots. Then we will do the following calculation: 14 plants x 10 square meters = 140 cuttings, this would be the approximate number of plants we could grow.

Fabrication of a tent structure for home growing tent

Once we are clear about the number of plants we want to grow, we will proceed to build the structure. We can use wooden slats to make the skeleton, and for the walls we can use plasterboard. If your budget is low and you don’t want to make a very big structure, you can line the walls with cardboard.

However, you may prefer to buy a grow tent and avoid the hassle.

Necessary material to grow cannabis plants indoors:

• Mylar reflective paper
• Lighting system
• Air extractor
• Air Intractor
• Aluminium tube
• Active carbon filter
• Thermo-hygrometer
• Light timer
• Humidifier or dehumidifier
• Pots
• Water collection trays or plates
• Cannabis seeds
• Soil
• Fertilisers

Buy indoor growing equipment

Once we have the structure built or the grow room cleaned and disinfected, we will have to buy the growing material we need. But to buy the material we need to know how to calculate the power of the lighting or the power of the air extractor and intractor.

Lining walls with reflective Mylar paper

To improve the reflection of the light we are going to place, we can cover the walls with Mylar reflective plastic, this will allow us to make better use of the light.

Lighting for indoor growing

Nowadays there are several types of lighting available for growing cannabis indoors. Here are the types of lighting that exist and how to calculate the necessary power.

Types of grow lights

• High Pressure Sodium lighting
• Energy-saving CFL bulbs (only for surfaces up to 80 x 80cm)
• LED lighting
• LEC lighting

Currently the most cost-effective and efficient are LED lighting panels, but the price of these lighting systems is not affordable for everyone, as the price is a bit high.

How to calculate lamp wattage?

If we cultivate with conventional sodium lamps, we advise to calculate the lamps as follows.

Watts	Area
250w	80 x 80 cm
400w	100 x 100 (1m2)
600w	120 x 120 cm

So let’s suppose we have a room of 10m2, to calculate the number of lamps we will do the following operation: 400w x 10m2 = 4000w, now we know the total number of watts we will need, the next operation is to divide it by the power we want to use. If we want to use 600w lamps, we will divide 4000w/600w= 6,66 lamps, as we must leave space for watering and so on, in this case we advise to use 6 lamps.

If we want to grow with LED lighting, we will be guided as follows:

Area	Watts
60 x 60 cm	Hasta 100w
80 x 80 cm	100 – 200w
100 x 100 cm	200 – 340w
120 x 120 cm	340 – 600w
150 x 150 cm or more	600 – 1000w

If we cultivate with LEC lamps, we should be guided as follows:

Watts	Area
315w	120 x 120cm
630w	145 x 145 cm

Installation of an extractor air fan

Now that we know which spotlights we need, it is time to think about the extraction system we will need.

How to calculate the power of a crop extractor air?

To calculate the power of the extractor we must measure the size of our tent or room, we need to multiply the height by the width by the length of the space. The result will give us the cubic meters of our grow room, now to know the power of the extractor we must multiply the cubic meters of the room by 30.

• Minimum extraction volume required = (Height x width x length) x 30.

Example:

Room dimensions: 2 metres high x 5 metres wide x 5 metres long = 20m3 x 30 = 600 m3 (This is the minimum extraction power we would need for a room with these characteristics).

Now we can calculate the power of the extractor fan for the crop, and know exactly which one to buy.

Intractor installation of crop air

In a tent or grow room it is important to renew the air, but if we extract the air with an extractor fan, it is important to have an air extractor to bring fresh air into the grow room. The power of the air extractor can be equal to or less than the power of the exhaust fan, but never more. The minimum we could put in is ¼ of the extraction. If we need 600m3 of extraction, we divide it by 4 = 150m3 is the minimum power that we will need for the intraction.

Connecting tube for exhaust air evacuation

When we buy the extractor we must remember to buy the extraction tube, to evacuate the air from the crop. When installing the tube, remember that you cannot make too many bends, as this will reduce the power of the extractor. If you have to make a lot of bends to evacuate the air from the extractor, bear this in mind when buying the extractor, as you will need a little more power. We would multiply the power of the extractor by 1.3 for each curve.

Example:

• First curve = 600m3 x 1.3 = 780m3
• Second curve = 780m3 x 1.3 = 1014m3

Installation of an activated carbon filter

Smell is one of the most common problems in cannabis crops, so it is important to install an active carbon filter to reduce odours coming out of the extraction tube. The carbon filter is also measured in m3/h and this should be the same m3 as the extractor or higher, but never lower.

If we have a 600m3/h extractor fan, the filter should be 620m3 or higher.

Measuring temperature and humidity with a digital thermo-hygrometer

Don’t forget to buy a digital thermo-hygrometer, one of the keys to cultivation is to respect the temperature and humidity parameters and to know the temperature and humidity accurately you will need one or more of these devices.

Installation of a light timer

Another of the key parameters of cultivation is to respect a light cycle, and so that we never forget to turn the lamps on or off, it is important to buy a light timer or several timers, depending on the number of lamps we have.

A light timer is a device equipped with a clock, in which we can program the hours we want the lights to be on or off.

Light parameters for indoor culture:

Photodependent varieties:

• Growing: 18 hours of light / 6 hours of darkness
• Flowering: 12 hours of light / 12 hours of darkness

Autoflowering varieties:

• 18 hours of light / 6 hours of darkness (during the whole crop)
• 20 hours of light / 4 hours of darkness (maximum yield)

Humidity control in indoor culture

Once all the material is in place, we will measure the humidity in the grow room with the help of the thermo-hygrometer.

Remember that in growth we need a humidity percentage of between 50 – 70% humidity. If the percentage is lower, you should buy anair humidifier to help you increase the humidity in the crop.

If the humidity in the crop is too high, the only way to reduce the humidity is with the help of an air dehumidifier.

The size of the pots

As mentioned before, our advice is that if you grow from seed you should use 11 litre pots and if you grow cuttings you should use 7 litre pots. We would never advise you to use smaller pots.

In order to start our cultivation we only need to buy the substrate we are going to use, the fertilisers and the cannabis seeds.

High Quality Cannabis Seeds

It is very important to buy quality cannabis seeds, for example from Sweet Seeds, Barney’s Farm, Dutch Passion or other seed banks available in our online grow shop.