How to Choose the Best Lights for your Grow

Written by Max Anderson | 30 Oct 2020

📷 WCP 2018

Lights are essential because they largely determine your plants' grow cycles, their photosynthesis and therefore their health and their buds. Lighting is the food of your marijuana plants. When first creating your grow room make a blueprint to decide what system for water management, light and airflow you want to use.

Which lighting is best for growing weed?

There are 4 main types of lamps that you can use for growing cannabis:

  • LED grow lights

  • Fluorescent grow lights (T5 and CFL)

  • Metal Halide grow lights

  • High-Pressure Sodium grow lights

While each of these options has pros and cons, as well as different stages of the growing cycle and different sizes of operation they work best for, in this article, we'll focus more on the types that would be your bread-and-butter for a commercial-scale grow operation.

LED grow lights

LEDs are super easy to set up. Small ones are literally plug-and-play. Once you have plugged them into a wall you may just hang them above your plants. They are the way to go for an easy setup that still grows great yield.

Make sure to keep enough distance to your plants with LEDs to avoid light burn. Also, be sure to get a light that includes green and white light for a full spectrum. Only red or blue lights would not be enough for your plants.

LEDs are the way to go for small production up to 1 ounce of cannabis per month, but produce slightly lower yield per watt than HPS and Metal Halide lamps, and are generally less optimal for professional grows.

Fluorescent grow lights for cloning young plants

Fluorescent lights would be your go-to for the very first stages of your plants' lives. They don't use much electricity, they're cheap, and they're also very popular with many hobby gardeners and so are very easy to find.

Compact bulbs (CFL) that you can find in any hardware store can great for small or narrow areas, or grow tent setups for beginner grows. For a professional production, however, you would want to look for T5 Grow Lights (the long tube-like ones) which can be found in a home and garden centre.

These lamps are best used for cloning and seeding young plants. Without burning the plants, you are able to place them close to the plants and save electricity. Also, they do not produce a lot of heat, and the purple-white spectrum is ideal for seedling plants.

However, in the vegetative and flowering stages, keep in mind that fluorescents would lead to smaller yields. While T5 lights are great for small plants, in the later stages you would want to use a higher-powered light like HPS or Metal Halide.

Metal halide grow lights for vegetative stage

These lights are one of two types of High-Intensity Discharge (HID) grow lights and are incredibly efficient. Metal Halide (MH) lights typically come in an integrated fixture with an external ballast and reflector hood, which would need proper ventilation due to high heat output.

These bulbs, along with High Pressure Sodium (HPS), the other type of HID grow light, produce the highest yields per watt of electricity out of any grow lights available. For this reason, they are the go-to for professional growers in the later stages of plant development.

Metal halide produces a bluish spectrum which is ideal for the vegetative stage.

HPS grow lights for flowering stage

Similar to metal halide, HPS grow lights must be used with reflector hoods and ventilation. The fixtures used for Metal Halide bulbs and HPS are typically the same, so you can use the same fixture for both vegetative and flowering stages, and simply swap out the bulbs.

HPS produces a more yellowish/full spectrum that promotes budding and is ideal for the flowing stage. These bulbs are an absolute must-have for a professional grow.

Why your plants love light

Your plant's ability to perform photosynthesis is the key to your growing success. Make sure to put some thought into your lighting before getting started. Shining just about any light on your plants is not going to do the trick.

Light waves come in a colour spectrum. The sun is a full spectrum light. A low light intensity might lead so long plants because they stretch to receive enough light. When having high intensity your plants may turn our shorter. You can adjust the light intensity by choosing the distance from your plant.

In the vegetative stage, your plants would want up to 18 hours of light a day. In the flowering stage, they grow best in 12 hours of light and 12 hours of darkness.

Make sure you provide a minimum of 6 hours of darkness for your plants. The 12/12 hours flowering cycle would make your plant believe it is late summer which is their time to develop buds. You want to start this after 2 to 4 weeks of growth in the vegetative phase. This is the time where you can switch from fluorescents to HPS grow lights.

Grow lights are the heart and soul of your plants’ health. If you are small or on a budget you might start out with fluorescent lights but keep in mind that this would affect your yield. Use a mix of fluorescents and LED grow lights for the vegetative phase and HPS for the flowering stage for professional purposes.

Source: Production Grower