Do LED Grow Lights Need a Ballast?

When I first started growing cannabis, the hardest part was understanding all of the complex lighting requirements for my grow space.  There are several different types of grow light (LED, HID, Fluorescent ) with each one working differently and with its own set of requirements.

All of this can be pretty overwhelming for beginners, which is why we’re here to try and break it all down for you.

Today we’re looking specifically at the role of the lighting ballast.  Some grow lights require a ballast, while others do not. In this article, we’ll explain what a grow light ballast is, how they work and which grow lights you need them for.

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Do LED Grow Lights Need A Ballast?

Short answer: No, ballasts are not required for LED grow lights. Read on to find out everything there is to know about grow light ballasts!

What Is A Grow Light Ballast?

Simply put, a ballast is an electrical support system for an HID/HPS grow light. It regulates the amount of electricity your light produces, which prevents the light from overpowering, overheating, or catching on fire.

Sounds simple enough, right? Now let’s take a look at the science behind this clever technology.

What Does A Grow Light Ballast Do?

The main function of a grow light ballast is to regulate and control the amount of electricity your light is using at any given moment. It can increase, reduce, or maintain the current electrical output based on the light’s needs.

To fully understand how they work, we need to know what HID/HPS grow lights would do *without* a ballast.

How the electricity gets conducted

Generally speaking, a light conducts electricity in 2 ways: an electrical arc and a gas (see ‘sodium-mercury amalgam’ in above image), which starts in the form of a solid.  When your light is switched on, the electrical arc sparks, providing enough voltage for your light to turn on and heat up.  As it heats, the solid melts into gas, which continues powering the light.

Once the solid is melted completely, the light no longer requires as many volts to stay operational… if it continues to operate with that much energy, it could overheat, blow the bulb, or even catch fire.  That’s where your ballast comes in.

Without a ballast, HID/HPS lights will not spark at all… this is a safety measure created to ensure that you don’t use these lights without one.  Once hooked up properly, the ballast begins working immediately.

The main function of the ballast

The electrical arc that sparks the power only lasts for a second. After that, the ballast is in complete control of regulating the power.  It allows for high voltage in the beginning, since the extra power is needed to melt the solid into a gas.  Once melted, the ballast reduces the power and keeps it regulated.

How does the ballast do this?  It depends on what kind of ballast you’re using. There are two different types of ballast: magnetic and electronic.  Let’s take a look at both…

Magnetic Ballasts

This is older technology, so if you are using a second-hand ballast or have owned yours for a while, it’s likely magnetic.  These ballasts use copper coil wrapped around iron connectors to generate and regulate electricity.

This technology works well but creates a LOT of heat.  If you’re using magnetic ballasts, you’ll need to run fans or invest in a cooling system alongside it.

Electronic Ballasts

Modern technology wanted to find a solution to the heat problem, and so electronic ballasts were created.  Instead of using coils and metal, electronic (or digital) ballasts use electronic components like microchips and semiconductors to regulate voltage.

These run at a lower temperature but, even better, take up almost zero space… which means that most of these also include a built-in cooling system to keep the heat even lower.

Because the technology on these ballasts is so new, there haven’t been any ANSI standards set up for them yet, which means that you really have to do your research to make sure that you’re getting a high-quality electronic ballast.  Without these standards, the market is pretty inconsistent.  Take your time choosing, and don’t go for the cheapest one you can find.


So that was a lot of information, huh? Understanding how ballasts work can be sort of confusing, so I hope this helped clear things up.  As a review, let’s just recap when you do and do not need an external ballast for your grow light.

When you need a ballast

If you are using HID or HPS bulbs, fluorescents, or CFLs, you will need to check to see if the light has a ballast built in. If not, you’ll need to use an external ballast.

Additionally, if you are retrofitting an LED light to replace an existing HID or HPS system, you can buy plug-and-play LEDs that work alongside your existing ballast… this way you don’t have to completely remove your existing setup.  However, these LEDs do not require the ballast to work.

When you don’t need a ballast

Obviously, if your HID/HPS, fluorescent, or CFL light comes with a ballast built in, you will not need an external one.

Additionally, LED lights use diodes to produce their light which means they are easily regulated and require only a standard wall outlet to operate.  In general, if you’re setting up a new grow space, there’s no reason for you to invest in an additional component by adding a ballast.

James Alexander James Alexander
Hey, I'm James! The founder and head writer here at I started this site to share my passion and knowledge of all things cannabis. I used to work as a budtender in central Amsterdam, and have over 7 years of growing experience.

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