Selecting Grow Lights for Your Plants

To help your plants grow and to get the most out of them you’re going to want to have proper grow lights.  By having the right light, you’ll be able to influence the environmental factors for your plants. Lights help create the perfect air, soil, water, and light conditions for the plants. When you have more lights, this leads to a bigger yield.

We need lights because they help the growth cycle for your plants. Lights are part of the photosynthesis for the plants which impacts the health of them and how well they’re going to bed. You can think of light as the food for the marijuana plants. When you create your grow room for your plants you need to take into consideration water management, air flow, and light so you should design a blueprint for all of these things to make it easier to set up.

Choosing the Right Lighting

There are four main types of lights for cannabis plants which include the following:

  • LED lights
  • CFL or T5 fluorescent lights
  • Metal Halide lights
  • High-pressure sodium lights

Each one of these lighting options has both advantages and disadvantages. The lights that you get will all depend upon the size of the growing operation and the growing cycle of your plants. We are going to focus on a basic commercial-scale operation.

LED Lights

In terms of setup, LED grow lights are quite easy to work with. The smaller ones can simply be plugged in and then used. All you need to do is plug them into a wall socket and then hang them up of the plants. For a simple setup and great yield, these are the lights that you want.

These lights don’t tend to run very hot but if you have a professional production you need air flow and exhaust fans to regulate the temperature throughout the growing facility. You want to keep enough distance between the plants and the LED lights so there is no would like to burn. You want both white and green lights so you get a full light spectrum. Blue lights are red lights don’t provide enough the plants.

If you have a small production and reproducing around 1 oz of cannabis each month this is the way to go. They will produce a lower yield per watt than Metal Halide lamps or HPS And they are not optimal for professional grower.

Fluorescent Grow Lights and Young Plant Cloning

For the first stages of your plant’s lives, you want to go with fluorescent lights. These are cheap and they don’t use a lot of electricity and many hobby gardeners use them because they are quite easy to find. You can use CFL or compact bulbs that you find in hardware stores and they’re perfect for narrow or small areas. They are great for a beginner grower or any sort of tent set up. If you have more of a professional production you want to look T5  grow lights which look like a long tube. You can find these in your regular home garden center.

These lights work the best for young plants as well as for cloning and seeding. You can place them close to the plants which will save electricity and they don’t burn the plants because they produce less heat but compared to other lights. They are also in the purple-white spectrum which is perfect for seeding.

Once your plants get to the flowering in the vegetative stage fluorescent lights aren’t as good because they will lead to a smaller yield. The T5 lights are perfect for small plants but once they reach the later stages you’re going to want to use Metal Halide or HPS lights.


  • Use T5  fluorescent grow lights for propagation, cloning, and seeding stages. Note that regular lights bulbs should not be used as they don’t work.

Metal Halide for the Vegetative Stage

HID or High-Density Discharge lights are very efficient. MH or Metal Halide come with a fixture that’s integrated and they have a reflector hood and external ballast. They need good ventilation as they have a high heat output. HPS or High-Pressure Sodium is the other type of HID lights you’ll want to use. These will produce the highest yields per watt out of all the different grow lights in the plants later development stages. Metal Halide produce a bluish spectrum so this makes them perfect for the vegetative stage.


  • Once the plants get to the vegetative stage change the T5 fluorescents to HID lights. You want a ratio of 2 Metal Halid lights for each HPS light you have to get the maximum yield.

HPS Grow Lights and the Flowering Stage

HPS lights are similar to Metal Halide but need ventilation and reflector hoods. The fixtures for HPS and Metal Halide are usually the same so you should be able to use the same fixture for the flowering and vegetative stages and just swap out your bulbs. HPS is in the yellowish/full spectrum and this will promote buds so it is great for the flowering stage. If you want to be a professional grower, you really need to use these bulbs.


  • In the flowering stage, you want to make the switch over to HPS bulbs as this promotes budding and we’ll give you a maximum yield. since metal halide bulbs and HPS lights get quite hot you need an exhaust fan so the plants don’t get burned.
  • If you want the maximum yield for your marijuana then you need to look into HPS and metal halide bulbs. You need to factor in the cost and the extra work for setting up exhaust fans, cables, and the fixtures. You should also ensure that you have a digital ballast as the lights last longer and use less electricity.
  • When you use HPS halide and HPS lights assuming that they are high quality, they will produce two to four times more yield when compared to fluorescents.

Why The Plants Love Light

If you want commercial success with your plants then you need to help him perform photosynthesis but just shining a light on your plants is not going to work.

Light waves come in a certain color spectrum. The sun is considered a full spectrum light. When you have low light intensity you might have long plants because they are stretching to receive enough light. When you have high intensity the plants may end up being shorter. You can control the light intensity and choose a distance from your plants when using grow lights.

Once the plants reach the vegetative stage they require around 18 hours of light. In the flowering stage, they need around 12 hours of darkness and 12 hours of light. By being able to control the light yourself you can choose the right light timing for the plants.

Your plants should have six hours of darkness at a minimum. When you have a 12/12 flowering cycle the plant will believe that it is late summer and it will start to develop the buds. You should start this once 2-4 weeks is up after you have growth in the vegetative phase. This is when you want to switch from fluorescents to HPS grow lights.


You want a gentle switch from one light cycle to the other. You should take a couple of days to switch from 18/6 to 16/8 and then to 4/10 to 12/12.

A timer can help you do the switching. The lights will be on a set schedule and you are not going to have to worry about it. You can find timers online or in any store that does home improvement or sells electronics.


If you want your plants to be healthy and to get a good yield you need to invest in proper lights. If you’re on a budget or just have a small operation then fluorescent lights will work but the yield is going to be smaller. Try to use LED lights and fluorescent for the vegetative phase of growth and then once you get to the flowering stage and then use HPS lights if you want to be a professional grower.