When growing indoors it is important to consider your light source. There are many different types of grow lights each with advantages and disadvantages. We examine each major type of grow lighting so that you can choose the best light for your setup.

There is no substitute for the sun. By choosing the correct grow lights however, you can get very close. By carefully controlling the light available to a plant you can even trick the natural cycle and, for example, produce tomatoes in the middle of winter when the days are shorter.

While you can get away with a small pot in a sunny window for truly efficient growth you will want a dedicated grow light. There are a few different types of grow lights that you can use for your plants. The one you use will depend on your growing space, budget, and ventilation.

Take a look at each lighting type before deciding which one is right for you. If you still aren’t sure you can always reach out to us. We would be more than happy to help!

Before we dive into the types of grow lights we need to first discuss the spectrum of light.

Understanding Grow Light Spectrum

The sunlight we see is actually a bundle of different colored wavelengths. This is exactly what you see when sunlight shines through an angled piece of glass and you get that rainbow effect. Incidentally the visible light spectrum spans from the “red” end of the spectrum with longer wavelengths to the “blue” end with shorter wavelengths.

Natural sunlight outputs each of these wavelengths with a specific intensity. This is shown in the image below. The darker areas on the left and right represent the ultraviolet (beyond violet) and the infra-red (below red) regions of the spectrum.

Sunlight Wavelength Intensity
Sunlight Wavelength Intensity

Different types of grow lights output light more efficiently at specific wavelengths. This is important to consider if you want to precisely control your plant’s growth. Certain plants respond positively to specific frequencies but largely ignore the other ‘pieces’ of the light. Choosing the right light output will help you grow happier, healthier plants.

Metal Halide Grow Lights

Metal halide bulbs offer the best spectral distribution amongst grow lights. This means the light provides most of the same wavelengths found in natural sunlight. Metal halide bulbs offer good power output across the entire light spectrum, although they are less effective towards the red end of the spectrum.

Due to their broad spectrum and light output they work well for growing multiple different crops with a single light source. Metal halide bulbs also have a good life expectancy and do not lose as much power as fluorescent bulbs for example.

Metal halide bulbs are generally not very energy efficient. Typical power consumption ranges from 400W for compact models to over 1000W for more powerful units. That is like running an electric heater 24×7.

All this power also creates a lot of heat. This heat needs to be managed with efficient ventilation. Many grow lights include mounting points for ventilation ducts to exhaust the hot air.

High Pressure Sodium Grow Lights

High pressure sodium (HPS) grow lights are comparable to metal halide bulbs in output power and spectrum range. The one key difference to remember is that metal halide bulbs are less effective on the red end of the spectrum, while high pressure sodium bulbs are less effective on the blue end of the spectrum.

Fruiting and flowering plants prefer light in the red end of the spectrum making HPS lights perfect for plants in this phase. During the vegetative phase however, HPS lights should be supplemented by a secondary metal halide bulb.

As with metal halide grow lights, HPS lights output a lot of heat. This heat needs to be managed with efficient ventilation or your grow space will get quite tropical.

High Output Fluorescents and Compact Fluorescents

Fluorescent bulbs can also be used as grow lights. These tubes typically seen in laundry rooms and garages are usually cool to touch and can therefore be placed much closer to the plants. This is important as even “high-output” fluorescent bulbs are weaker than MH and HPS grow lights.

High output T5 fluorescent bulbs are perfect for starting seeds or clones as there is very little risk of burning the leaves with a more intense light. A common set up involves shelving units with seed trays and fluorescent fixtures mounted just a few inches above the sprouts.

Fluorescent bulbs generally output light closer to the bluer end of the spectrum. This makes them ideal for the vegetative phase, however they will need to be supplemented during flowering.

LED Grow Lights

Advances in LED technology have made them quite powerful. LED light fixtures provide power output comparable to a T5 fluorescent bulb. They also emit very little heat and can be placed very close to plants.

Plant growth when using LED lights is only slightly slower than MH/HPS bulbs. LED grow lights do not emit very much heat making them ideal for hobby setups without ventilation, although they are not suitable for very large plants. In this case a metal halide or high pressure sodium bulb is the best option.

LED grow lights are also much more energy efficient than other types of lighting.

Choosing the Right Grow Light

We have covered the various types of grow lights. Which one you ultimately use will depend on your plants’ requirements, available space, and budget.

Keep the following in mind and you will do great:

  • Metal halide and high pressure sodium bulbs are more expensive, and produce more heat, but provide a much higher output and in turn better plant growth.
  • LED and fluorescents use less energy, produce less heat, but have a lower output. However, LEDs and fluorescents can be placed much closer to the plants.

Of course if you haven’t already, you will need to select what type of hydroponic system you will use. Combine that with the right type of lighting and you will be well on your way to growing your own produce right at home.