How to Set Up an Indoor Cannabis Grow

From the very moment you start planning an indoor grow, the first thing to consider is choosing the spot where the plants will go. For this you'll find two options:

1- Buy a grow tent

2- Adapt a space for growing

If you choose to buy an indoor grow tent, you'll see that it's one of the easiest and most convenient ways to start growing, since all of its structures arrive ready to set up and plug in.

You'll be able to find different sizes that adapt to all kinds of spaces, from 60x60 tents for tight spaces, to roomier 120x120 ones, and even giant 240x240 tents.

The advantages of using grow tents are many, and these are some of them:

a- They are built to accommodate whatever you want to place inside so the grow thrives (reflectors, fans, extractor, ducting, etc.).

b- Their fabric, being impermeable to both water and light, keeps the grow discreet and ensures the plants aren't affected by outside light.

c- The interior walls are made of a reflective material, so you'll make better use of the light.

The second option is to adapt a closet or room for growing. And in this case you have to do a bit more work to put in certain types of installations.

Adapting these spaces usually involves installing lighting specific to growing, reflective material on the walls to boost the light, covering the windows with black-out fabric so light neither enters nor escapes, covering the floor with plastic to prevent water damage, and installing ventilation and air extraction that allow good airflow.

How Many Plants Fit per m²?

This is one of the most frequently asked questions from those starting out in indoor growing. And the answer isn't simple, because it will depend on a series of factors to consider:

a- Plant size: you can choose to grow a few large plants, or, conversely, many small ones. Whatever you decide, keep in mind that caring for two is not the same as caring for seven or ten.

b- The time you'll be able to dedicate is a very relevant factor when deciding.

c- Pot size: the bigger the pot, the more room the plant will have to develop and the larger it will be. An average pot will be roughly 11 L.

d- Strain type: generally it's sativa plants that tend to be taller and slimmer, while indicas are shorter and more robust. In addition, the former take longer to flower.

e- Autoflowering or feminized: autoflowers are smaller and flower in 2 months, while feminized plants can grow quite a bit and usually need at least 2 months of flowering. They're generally given at least a month in vegetative growth.

f- Light power: if the space you're using is fairly large, but you only have a 250-watt bulb, it's not worth putting in 10-12 plants.

g- Time in vegetative: if the vegetative period is short (we're talking about a month or so), you'll have smaller plants, and therefore you'll be able to fit more. Conversely, the longer it is, the larger the cannabis plants you'll get.

h- Techniques you're going to use: if you're going to use a specific technique, such as SCROG, you can place one or two plants per m², since the idea is that with the screen the branches cover the space. On the other hand, if you're going to do it with the SOG technique, what you'll be looking for is many colas that take up little space and that allow you to use several pots.

How to Calculate the Watts You Need for Your Grow Based on the Space? With Sodium (HPS) and Metal Halide Bulbs

As has been known for many years, sodium was one of the most widely used types of light in cannabis grows because of the spectacular results it brings to the harvest. However, the big problem with this type of light is that it gives off a lot of heat and generates high electricity costs. That's why it isn't usually recommended for very small spaces (such as 40x40 tents, for example).

With this in mind, the ideal is to follow these recommendations so that your indoor grow thrives:

a- Watts according to space:

60x60 cm with 250 W

80x80 cm with 400 W

1x1 m with 600 W

You'll also be able to find 1,000 W bulbs on the market. However, for someone who is just starting out in indoor growing they aren't recommended, because they give off a lot of heat and, for them to bear fruit, you'll have to know how to control them and get the most out of them.

To make better use of sodium bulbs it's important to use a good reflector that distributes the light evenly, so your plants can grow robust and strong. Using a cooltube would also come in handy to bring the temperature down a few degrees.

b- LED panels: these offer results similar to sodium. The advantage? These panels consume less electricity and give off much less heat.

When you have to figure out which LED you'll need for your grow, the ideal is to consider the amount of usable light the plant requires that the panel emits, and not the watts the manufacturer states. That is, buying a 1000 W LED panel may not be the best for your grow if it only provides 15-20% efficiency, as happens with some panels, since this way the cannabis plants would only be receiving 150-200 W.

To know how much space the LED panel covers, the ideal is for the manufacturer to already provide a chart showing the amount of usable radiation in a given space (or PPFD, which is measured in μmol∙m²∙s). This value will vary depending on the height at which it's measured.

This way, you'll know how much space the panel will cover and you'll be able to see whether it will be enough for the space you have available for your plants.

It's important to keep in mind that, during the early stages, on clones or mother plants, the LED has to be positioned at a greater distance and 200 to 400 μmol∙m²∙s will be enough. For vegetative, it will rise to 400-600, and in flowering it should have a higher intensity, between 600 and 900.

Having an indoor grow isn't difficult if you prepare in advance with all the elements we listed above and pay special attention to the space and the strains chosen.

How Many Hours of Light Does an Indoor Plant Need?

The hours of light needed for indoor cultivation of cannabis plants vary depending on the growth stage the plants are in. In general, during the vegetative growth phase, it's recommended to provide 18 to 24 hours of continuous light per day. During the flowering phase, it's recommended to provide alternating 12 hours of light and 12 hours of darkness to stimulate flower formation.

It's important to keep in mind that home indoor growing requires careful planning of lighting, ventilation, and other environmental factors to create a suitable environment for plant growth. LED lights are a popular option for indoor growing, since they are energy-efficient and emit the amount and quality of light needed for the growth of cannabis plants.

In addition to lighting, ventilation is also important in an indoor grow to maintain a suitable environment for plant growth. Fans can be used to promote air circulation and help maintain appropriate humidity and temperature levels inside the grow space.