Before you start growing marijuana indoors, you must make the important decision of choosing the type of lighting that best suits your needs.
Either HPS (High Pressure Sodium – high pressure sodium vapor) or MH (Metal Halide – metal halides) which, due to its low installation cost, is recommended for novice growers. In general, the most common choice is still high intensity discharge (HID) light. If you are interested in LED lights for growing, you will also find some tips in this article.
High intensity discharge (HID) lights
What are HID lights? The High Intensity Discharge (HID) light provides for the cultivation and growth of hydroponic marijuana, a low consumption light source.
HID lights are considerably cheaper than LEDs, and are a popular option for many growers, despite being less effective overall. There are two types of HID light that can be used to grow marijuana indoors: the MH (metal halides) and the HPS (high pressure sodium vapor).
During the entire cultivation process – from seed to harvest – we can use either of the two types of lighting, but it is not the most recommended, it is best to use the MH during the vegetative phase and you can also take advantage of the points strengths of each type of light if they are alternated according to the different stages of maturation of the plant, to maximize its growth and production.
During the vegetative phase, MH would be used and later, during the flowering phase, we would switch to HPS.
HID Lights – Most Common Sizes in Watts
- 1000W – from 46 to 66 centimeters of margin
- 600W – from 30 to 46 centimeters of margin
- 400W – from 23 to 30 centimeters of margin
- 250W – 15 to 20 centimeters margin
Our recommendation The choice of watts will be determined by the variety and number of plants you want to grow, the growing area, and the amount of vegetative growth your plants require. Bulbs under 400W are generally quite ineffective in our opinion, it is much better to use a CFL light. Those of 1000W or more are also considered ineffective by most indoor growers. 1000W bulbs are large, produce a lot of heat, need headroom above plants, work best with CO2, and generally work great if you’re a more commercial grower. Many hobby growers will have more than enough 400 and 600 watts.
You have the option of buying many 400W and 600W models, spreading them out evenly, reducing hot spots, and compared to a single large 1000W model, you would still be able to cover more growing area. Keep in mind that for ten or fifteen plants or five large plants in pots of eleven to nineteen liters capacity, a 1000W or a 400W plus a 600W is fine.. Use this reference for lower wattage lighting systems. Think that, according to most successful growers, it can range from 10,000 to 15,000 lumens for every 0.1 square meter.
MH or metal halide lights
Generally, metal halide lamps replicate the natural light of the spring and fall months, as they produce a blue light spectrum of 6,500 to 7,200K. This is why they are the best to use during the vegetative phase of marijuana production, which is the earliest phase. MH lamps, when used as the primary light source in an indoor growing system that does not receive natural light; They favor the growth of green and leafy plants, with stems, branches and leaves that will produce bushy plants and of shorter stature.
Although not recommended, MH lights can be used throughout the growth cycle. It is best to start with MH and switch to HPS for the flowering phase, however if you can only buy one bulb, it is better to choose one from HPS.
HPS or high pressure sodium vapor lights
HPS or high pressure sodium vapor lights emit an orange / red light spectrum, making them the best choice during the breeding or flowering phase of marijuana cultivation.
HPS lamps are very effective, however, the lack of blue light spectrum makes them suitable, but not ideal for the vegetative phase of plants in indoor crops, which do not receive natural light. Indoor plants that, in their vegetative phase, have been exposed only to HPS-type lights, tend to grow very fast and are quite thin.
It is in the flowering phase that the HPS lights play a fundamental role. The orange / red light spectrum is perfect for activating the hormones of marijuana plants and increasing their flowering. Marijuana grown hydroponically using HPS lights produces better yields than those grown with MH lights only.
A drawback of HPS lights is that they consume a lot of energy and generate a lot of heat that needs to be counteracted with air conditioning or an exhaust system that represents a greater initial investment for the grower.
Combine HPS and MH lights
Combining MH and HPS lights using MH bulbs as the primary light source and HPS bulbs as the secondary light source during the flowering process is the option often used by the most sophisticated growers.
You can also buy MH and HPS bulbs combined in the same reflector, either with separate or integrated resistor assemblies. This solution is not considered particularly effective as these bulbs have less power, are more expensive, and are short-lived.
A light installation that allows you to decide when to use MH or HPS, but not simultaneously, is a better solution. This type of lighting is known in two ways: convertible or switchable. This makes it easier to switch from the MH to the HPS focus in the playback phase.
High pressure sodium vapor against metal halides
Metal halides (MH)
- Light spectrum: Azul (MH)
- Average duration: Up to 10,000 hours (MH)
- Best phase of plant growth: Vegetative (MH)
- Advantage: Simple and easy to use, ideal for small crops, cost effective. (MH)
- Drawbacks: Less durability, lower production is obtained if it is not combined with MH. (MH)
High Pressure Sodium Vapor (HPS)
- Light spectrum: Orange / red (HPS)
- Average duration: Up to 18,000 hours (HPS)
- Best phase of plant growth: Reproduction / flowering (HPS)
- Advantage: Higher production is obtained, better as secondary light, long duration, good for cool areas. (HPS)
- Drawbacks: It consumes a lot of energy and generates a lot of heat, not suitable for confined spaces. (HPS)
Production with HID lighting
In addition to the type of lighting you use, the production you can expect to achieve will depend a lot on the variety of marijuana you have chosen to grow, the quality of light (new or old), environmental factors such as ventilation, humidity or heat, the installation of the hydroponic system and of course, the nutrients you use.
We have prepared a table in which we show a reference of the production that you can expect. The maximum level would be one gram per watt, but even some of the most expert growers don’t get those results:
- 250 watts: 80 – 250 grams (production * – HPS)
- 400 watts: 120 – 400 grams (production * – HPS)
- 600 watts: 250 – 600 grams (production * – HPS)
- 1000 watts: 350 – 1000 grams (production * – HPS)
- 250 watts: 10% less approx. ** (production – MH)
- 400 watts: 10% less approx. ** (production – MH)
- 600 watts: 10% less approx. ** (production – MH)
- 1000 watts: 10% less approx. ** (production – MH)
* The competence of the grower, among many other factors, will be decisive in the actual production of marijuana obtained.
** MH bulbs contain a UVB light that, while producing less than HPS lighting, can increase the potency of the marijuana produced.
HID lighting systems cost comparison
HID lighting systems are much cheaper than LEDs, however, their low durability, high energy consumption, the limited light spectrum and the excess heat they generate makes LEDs, in the long term, cheaper.
You want to be sure that everything will work correctly and that you have an after-sales service for what could happen, so always make sure to buy your bulbs and lighting systems in places that have a good reputation.
- Kit 250 watts (prices from: 90 € -120 €)
- Kit 400 watts (prices from: 100 € -130 €)
- Kit 600 watts (prices from: 120 € -150 €)
- 1000 watt kit (prices from: 450 € -550 €)
* Prices include resistors, reflector and lamp are suitable for both MH and HPS. The price of systems with digital resistors corresponds to the highest in the price range.
Running your grow lighting system is not cheap. Plants need a lot of light and by depriving them of natural light in the grow room, you have to replicate the sun’s rays, which is what they want. The more light, the bigger and more powerful your plants will become.
Here is the average cost of electricity based on kw per hour in Spain, approximately it corresponds to € 0.14 / kWh.
- Six weeks on average for the vegetative phase for 24 hours a day is 1008 hours;
- Six weeks on average for the flowering phase for 12 hours a day is 504 hours;
Therefore, 1512 hours at € 0.14 / kWh make a total of € 211.68
Our recommendation of popular HID brands
HID lighting systems for crops
For the hydroponic cultivation of marijuana, a lighting system using HID lights consists of bulbs, a reflector to maximize the effectiveness of the bulbs and a resistor that boosts the energy
There are also different technologies available for both resistors and reflectors, in addition to different types and sizes of focus.
There are magnetic and digital resistors. Magnetic resistors are the conventional method of regulating the energy of the bulb by means of a system of capacitors and coils. And there are also the sophisticated digital resistors, which provide a constant flow of energy that increases the light irradiation of the bulbs, in addition to providing a configuration system for greater control of light output. The resistors are available to work with any of the HID lighting systems, be it HPS or MH.
Our recommendation is that you get a system that includes a bulb, resistor and reflector.
When using HID lights, the reflector is another important part of the lighting system as it helps to maximize the effectiveness of the light produced. Eagle, parabolic, refrigerated, etc, are some types of reflector that we have.
It is preferable to buy a complete system than to try to buy the parts separately. Fortunately, there are many establishments (physical and online) that will be happy to sell you, according to your needs, a complete HID lighting system.