Basic guide for indoor lighting: LED, HPS and HQI

When choosing indoor cultivation, it is necessary to think about the entire structure so that your plants grow and develop healthy – and, as lighting is a “recreation” of the sun, it is one of the most important parts of cultivation. Come and discover everything you need to know!

Whenever we think about the home growing of cannabis, we can highlight several benefits – from knowing exactly what you are consuming to the independence of trafficking and the infamous brick weed. But, as we live in the midst of prohibitionism, we know that this is not an easy choice as it seems. Here, for example, outdoor cultivation becomes a less valid option due to the dangers of exposure, although it is a more sustainable and holistic way of giving life to our plants.

That is why many resort to indoor cultivation, a more discreet way to generate healthy buds and learn more about the herb! This type of cultivation will require a pre-planned structure: space for plants, studying air, air conditioning and, one of the most important points, lighting.

As we already said here on the blog, lighting is essential for any cultivation because, in each of its phases (from vegegtative to the flowering and harvest), a cannabis plant will need more or less light to develop completely . As in an indoor space we don’t have the sun, our natural source of light and heat, we need to choose the perfect lighting to fulfill this role!

So, let’s find out more about this subject? We have prepared this basic guide to show you what types of light are available, their intensity, how much they represent in your grow and in which to invest.

Indoor grow
Indoor grow

Three main types of artificial light

To start, let’s talk about the basics: LED, HPS and MH are the main types of lamp for those who want to build an indoor grow. Ordinary fluorescent lamps are not so recommended: they can even be useful during the vegetative stage or to help clones root, but their low power makes it more difficult for your plant to reach its full potential. So, let’s put it aside here, okay?

Before we show you more details about these artificial lights, let’s first show you two very important measures when we talk about the subject: Watts and Lumens!

What do Watts and Lumens indicate?

Watt is a unit of power measurement that indicates the amount of energy the lamp uses to produce light. The Lumen is the standard unit of the international measurement system to define the luminous flux of a lamp.

The lumen is the amount of light emitted by the lamp falling on a square foot (width x length) of a surface that is one foot (0.3048 m) away. One foot can be rounded to 30cm – so first of all, convert your foot space measurement. In this way, it is possible to make the calculations avoiding errors.

The relationship between Lumens and Watts determines the so-called “luminous efficiency” expressed by the unit lm / W. This measure represents how many Lumens are produced for each Watt of energy consumed. The higher this value, the more advantageous the lamp is for your income and the electricity bill. If the measurement is not on the package, just divide Lumens/Watts and you will have the answer.

Lets go to what matters!

MH lamps

Metal vapor or metal iodide lamps (MH or HQI) are well known by those who have an indoor grow. That’s because they are relatively inexpensive for those just starting out!

What are they advised for?

These lamps are usually advised for the vegetative phase of cultivation. They are more powerful than fluorescent ones and emit more Lumens at a color temperature of 6500k. However, if used in flowering, they can give rise to plants with a more varied and more complex spectrum!

What is your point of attention?

It is necessary to pay extra attention to the ventilation and cooling of the place, as they can considerably warm up the environment.

HPS lamps

HPS (High Pressure Sodium) lamps are already a little different: yellowish in color, they are also cheap and are well known to growers. The 600W – 1000W, accompanied by an exhaust fan, can be great – and is widely used in industrial cultivation and can also be a great option for your small grow.

What are they advised for?

They are best advised for the flowering stage.

What is your point of attention?

HPS lamps generate the same type of concern as MH. In fact, apart from the phase in which their use is advised, they are very similar and are usually used in a complementary way to each other – MH during vegetative cycle and HPS for a more efficient flowering cycle, so to speak. But both produce heat and will require a good air conditioning and ventilation system to keep temperatures and humidity in the ideal pattern for the growth of your plants.

Led lamps

While HQI and HPS are more “old school”, LED lamps are the most modern type of lighting today. In addition to consuming less energy than other lamps, they produce much less heat (commonly 20-40% when compared to HPS) – so they end up being more economical in the long run and a good option for those who can already invest in lighting right away.

What are they advised for?

The most modern are the white full spectrum LEDs, which provide specific light spectra for each stage of plant growth, that is, you will not need to change the lamp between one stage and another.

What is your point of attention?

As the variety of models of this equipment is large, it is common that you have doubts when defining which is the most suitable for your cultivation. Most LED lamps are sold with Watts specifications, which are equivalent to those of ordinary lamps. However, this is not the real characterization of LEDs.

Science has shown that a watt is a watt, through and through so how can these LED companies make such crazy claims? The increase comes from efficiency increases. LED lights with proper spectrum produce less heat, and deliver light in a more direct and uniform fashion to the plant canopy. In this way a 600w LED can achieve similar yields to a 1000W HPS bulb, all while pulling 40% less watts and putting out anywhere from 10-25% less heat. LED fixtures also lack the IR light output of HPS and MH lighting so leaf temperatures remain lower and ambient room temperatures can be kept about 5-8 *F higher than in an HPS grow to achieve the same leaf temperature. LED is a more sustainable option overall through many harm reduction strategies. Lower power consumption, less heat, and no need for bulb changes creates a much lower foot print over time.

Lights for indoor grow
Lights for indoor grow

How much light will I need?

To calculate the amount of light you will need, you need to calculate how much space of your grow will be occupied by the plants. In the vegetative phase, around the fourth week, they tend to occupy more or less about this:

From that, you need to have a sense of how much light is needed according to the type and its total area:After all, which is better?

There are, as we have already shown, several factors that will influence the purchase of your lighting structures. We believe that LED lamps are the most efficient and environmentally friendly – and that, although they may seem more expensive, they are much more economical in the long run, as they do not require exchanges between phases, do not require large temperature control devices and do not spend a lot of energy.

But nothing prevents you from testing them all, at the most appropriate stages, and choosing your favorite.

MH reaches more blue spectrum, while HPS reaches red ones. In other words: one produces a “cooler” light, and the other in warmer tones. Most people use blue for vegetative and red for flowering, but you can make a mix – if you have more than one light you can have one bulb of each to balance the spectrum, or switch the bulb out as often as possible .

Calculate total spend and take the test

To find out how much you are going to spend on light, find out the daily consumption of your grow with the calculation: Watts consumed per hour X Number of hours the light stays on during the day. After knowing this result, you must multiply the value by the number of days in the month.

Our biggest tip is: start with what you can! We know that not everyone who will start growing already has all the latest technology available, and the good thing about going through all the steps is learning. You can actually start planting with fluorescent lamps and evolve as you see fit – or as you have the money to update!

An interesting idea is to research LED panels made at home, if you already want to start with the most technological lamps. The cost-benefit can be much better than buying the finished structure, and it will give you great results!

So, were you able to better understand the difference between the types of light and find out which one is ideal for your grow? If you have any questions, just let us know in the comments!

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