When to Replace Grow Lights

Not sure when to replace grow lights? Your grow lights are an integral part of your hydroponic system. However, most grow lights lose some efficiency over time, which can ultimately affect your yields. This guide shows you everything you need to know about grow light replacement and maintenance. We’ll go over the three main types of grow lights: LED (Light Emitting Diode), fluorescent, and HID (High Intensity Discharge). 

Example of lettuce under LED grow lights

Not All Grow Lights Last the Same

It’s easy to think you should replace your grow lights at the same intervals, no matter what kind you have. The truth is, replacement times actually vary widely. Likewise, the efficiency they lose over time is vastly different from one to the next. If you use the same timeline to compare them, one light might only lose about 5% efficiency, while another could lose 30% or more in the same timeframe. 

Understanding how your grow lights work, and the length of their functional lifetime can save you a lot of stress and work later on. If you’re going to the work of making sure you have the right lights, positioning, and output, you may as well know a thing or two about maintaining them.

Related: Which grow lights last the longest?

Looking for lights that outlast the others? If you’re wondering which grow lights last the longest, here’s the short, simple answer: LED lights. 

See this guide to learn more about types of lighting for hydroponics.

How Often to Replace Fluorescent Grow Lights

Fluorescent grow lights are known for producing light that falls primarily on the blue end of the spectrum. While they may not be the ideal fit for every grower, they do have some advantages. Namely, their efficiency and how long they last. While some lights do lose efficiency within the timeframe of their target use, fluorescent lights are pretty reliable. 

T5, the most common and effective type of fluorescent grow lights, are the best example. These lights typically last for around 20,000 hours before you need to replace them. However, some T5 lights are best used for only around 10,000 hours. Most grow lights come with indicators that give you a general range of how long they’ll last. 

After a year or two, many fluorescent lights begin losing their efficiency. However, it really comes down to how often you use them, and for how long. If your T5 grow lights are rated to last for 20,000 hours, they can actually last much longer. For instance: if you keep the lights on for about 16 hours a day, that light could last about 1,250 days, or just under 42 months. 

That said, a big part of how well a fluorescent light maintains efficiency over this time also depends on the ballast, or fixture, you use. The higher quality the ballast, the better the energy regulation. As a result, the lights last longer than they would with a low quality ballast. 

How Often to Replace HID Lights

HID, or High Intensity Discharge, grow lights are a classic for hydroponic growers. They provide plenty of high intensity light, but there are two main kinds of HID lights. There are MH (Metal Halide) and HPS (High Pressure Sodium). MH lights provide more blue light while HPS lights provide more red light. That’s not the only difference between the two, either. For instance, each needs a ballast designed to work with each type of bulb, unless you use conversion bulbs. 

There’s also a difference in how often you need to replace each. Here’s what you should know:

Replacing HPS Grow Lights

Typically, High Pressure Sodium grow lights last around 24,000 hours. However, because they lose efficiency over time, many growers suggest replacing them every 1 ½ to 2 years. Much like with fluorescent bulbs, the quality of the ballast can play a large part in how long your bulbs last. 

Replacing MH Grow Lights

Most Metal Halide Grow lights last anywhere between 6,000 and 15,000 hours. Considering that 24 hours a day, for an entire year is 8,760 hours, you can expect MH lights to last around a year or a year and a half depending on the exact bulb you buy. 

How Often to Replace LED Grow Lights

LED grow lights are one of the newest technology advancements for indoor hydroponic growers. There are plenty of benefits to using them, and efficiency is one of those at the top. 

If you’re concerned about longevity, LED grow lights should be your top choice. 

Light Emitting Diode, or LED, technology uses very little energy, while still putting out intense light. Many LED grow lights allow for full spectrum light, or allow users to switch between red and blue light. While the longevity of LED lights varies slightly depending on the quality of the components, they last significantly longer than any other type of grow light. 

As an example, the average LED grow light lasts about 50,000 hours. That means you get anywhere between 2.5 to 5 times longer use out of them

Some LED lights even last up to 100,000 hours. That’s between 5 and 10 times longer than other types of grow lights. 

So how often do you actually have to replace LED grow lights?

If you get a really well built, high quality set, it’s quite a while before you replace them. In fact, 5 to 10 years is fairly standard. At the very least, you can expect several years of use before they need to be replaced.

Learn more in our LED grow light guide!

Frequently Asked Questions

Does how long I leave my lights on affect how long my grow lights last?

Actually, it has a huge impact. That’s the main reason grow lights are usually labeled or rated in hours, rather than days or months. If someone only uses their grow lights for five or six hours a day, they can last several times longer than with a 16/8 or 20/4 lighting schedule. Most grow lights are rated with the assumption they’ll be turned on for around 24 hours each day. You can choose to replace your lights after a certain number of months or hours depending on your photoperiod.