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How Much Power Do Grow Lights Use (LED vs HPS)?    

Grow lights are electric lights that provide a light spectrum tailor-fitted to the needs of indoor plants. They mimic the light spectrum provided by the sun in an outdoor environment. There’s a wide array of grow lights in today’s market, but two of the most commonly used varieties are Light-Emitting Diodes (LED) and High-Pressure Sodium (HPS) lights.

Grow lights use more power than regular lights, requiring between 32 to 73 watts to illuminate a square foot (0.09 sqm) area. However, not all grow lights are created equal, and some will consume less or more electricity than others.

In the following sections, we’ll dive further into the differences between LED and HPS grow lights. We’ll highlight their energy consumption, average cost per hour, and how much impact they can have on your monthly electric bills. Let’s get the ball rolling!

Photo of two LED grow lights hanging above pepper plants with two black oscillating fans hanging off to the left
Here is my grow tent set up, two LED grow lights with two oscillating fans.

Do Grow Lights Use a Lot of Electricity – LED vs. HPS?

Grow lights do use a lot of electricity, compared to regular lights; however, LEDs consume less power than HPS lights without sacrificing output. Therefore, LEDs are the grow light of choice for gardeners aiming for healthier growth in their plants without breaking the bank.

There are many types of grow lights to purchase, each offering unique benefits to cater to the varying needs of different kinds of plants. Two of the more popular choices these days are LED and HPS grow lights. Let’s look at each of them closely to better understand what they have to offer.

LED Grow Lights

Light-Emitting Diodes (LED) grow lights are widely favored by gardeners because they are proven to be more energy efficient than most other types of grow lights. They can produce the same amount of light as HPS lights but without using as much power. LEDs produce less heat as well. In fact, they can be positioned near your plants without causing any leaf burns. Furthermore, LED lights are much smaller than HPS lights and last longer.

The only issue frequently raised about LED grow lights is their cost. You would need to shell out more money upfront for these lights. However, keep in mind that they are more energy efficient. This means that you will be spending less money in the long run, especially in terms of electricity costs, if you decide to go for LED lights today.

HPS Grow Lights

High-Pressure Sodium (HPS) grow lights produce more intense light than LEDs. This translates to more heat production, which is an essential growth factor for some plants, particularly seedlings. If you’re keen on making your plants grow lusher and begin to produce fruits or flowers sooner, you’ll be at a slight advantage with HPS lights. You’ll be spending less on up-front costs too.

However, HPS grow lights are less energy efficient than their LED counterparts. They require more power to produce practically the same amount of light. The amped-up heat they produce also requires a bigger space and better ventilation for airflow to avoid wilting, burning, and heat stress on your plants. Furthermore, HPS grow lights have a shorter life expectancy than LED lights, so you’ll be shelling out more cash in the long run.

How Many Watts Do Grow Lights Use – LED vs. HPS?

LED lights use about 32 watts to illuminate a square foot (0.09 sqm) area. If you have HPS grow lights, you will need at least 37 watts for an area of the same size, that is 16% more watts. Note that plants require varying amounts of light depending on what phase of the growth cycle they currently are in.

LED lights are not standardized. The more efficient ones will need fewer watts to emit a certain light level than the less efficient varieties. On the other hand, HPS grow lights are generally more consistent, so determining wattage requirements is pretty simple. LED lights can be mounted right above your plants, while HPS grow lights need to be anywhere between 2-6 feet (61-183 cms) away from your plants due to the intense heat they emit.

HPS lights that are 100-250 watt (W) need to be mounted 2-3 feet (61-91 cms) away from the tops of your plants. Medium wattage HPS lights, ranging from 400-600W, should be at least 4 feet (122 cms) away. High wattage HPS lights clocking in at more than 1,000W must be mounted 4-6 feet (122-183 cms) away from your plants.

Photo of grow lights hanging above pepper plants in a grow tent
Photo by Spicy Trio

How Much Electricity do Grow Lights Use per Hour – LED vs. HPS

In the U.S., the average price of electricity for 2022 is roughly $13.75 cents per kilowatt-hour (kWh). Indoor plants generally need 14-16 hours of light daily to grow and thrive. Keep in mind that the higher the wattage of the grow lights you’re using, the higher your electricity consumption and cost.

If you have a 600-watt grow light and use it for 16 hours every day, your daily energy consumption is 9.6 kWh. This translates to an additional $1.32 per day. You would need to shell out around $39.6 for additional electricity per month for your grow lights.

So is 600 watts the average consumption for a regular indoor garden? Actually, this figure is on the higher end of the scale. Ten average-sized indoor plants grouped together would only need around 300 watts for them to grow and thrive. You would need even less if you have just a few plants scattered here and there around your home. In fact, it would only cost you around $2 per month to provide light for one small indoor plant.

As previously mentioned, LED grow lights can generate the same amount of light as HPS grow lights without using as much power or wattage. The lower the wattage of your grow lights, the more you’ll be able to save on electricity. In this regard, LED lights will use less electricity per hour than HPS lights.

Will Grow Lights Impact My Electricity Bill – LED vs. HPS?

The amount of electricity your grow lights use can vary depending on certain factors. One factor is the number of hours you use your grow lights daily. Another is the wattage of the grow lights you’re using. LED grow lights are usually 3-5 times more expensive up front than HPS grow lights. However, they are about 40% more energy efficient.

LED grow lights will have less impact on your electricity bills than HPS lights. HPS lights need more power to generate the same amount of light. Moreover, they require additional equipment, such as humidifiers, temperature controls, and exhaust fans, to help manage the heat they produce.

When to Use HPS Grow Lights

HPS grow lights may not be as energy efficient and practical as their LED counterparts, but they have the upper hand for certain qualities. After all, they were the grow light of choice for most farmers and gardeners long before LED lights came into the picture.

Some gardeners still believe that LED lights may sometimes fall short in terms of encouraging certain plants to reach their full potential since they are not as powerful, especially heat-wise, as HPS lights.

Here are some scenarios where HPS grow lights might be your better option:

  • You’re growing flowering plants and flowers. HPS grow lights feature a broad color-temperature spectrum that helps plants in the reproductive and flowering phases.
  • You’re growing vegetables. HPS lights aid and enhances a plant’s fruiting phase.
  • You’re growing seedlings. The orange/red spectrum from HPS lights aids in a plant’s vertical growth.
  • You’re growing plants that need intense light. Plants such as tomatoes and peppers need a lot of light to thrive and produce crops. That said, we grow lots of peppers with LED grow lights!

When to Use LED Grow Lights

LED grow lights are undoubtedly the best choice if you are keen on energy efficiency and reducing electricity costs. You can get the same amount of light minus the intense heat without spending as much on electricity. This is why LED lights quickly become the top choice among most indoor gardeners.

Here are some other reasons why you should consider LED grow lights for your plants:

  • You’re growing low-light plants. Herbs and leafy greens, like basil, lettuce, and cabbage, do not require as much light and heat to thrive.
  • You’re growing fragile plants. Leaf burn is one of the risks of having HPS grow lights aimed directly over your plants. Those with tender, sensitive leaves will benefit from the softer illumination of LED lights.
  • You do not have a big space for your plants. LED lights can be mounted inches away from the tops of your plants. They do not emit intense heat, so you wouldn’t have to worry about leaf burn and heat stress.
  • You’re not keen on paying more for ventilation systems and temperature control gadgets. Since LED grow lights do not emit intense heat, in many cases, you do not have to purchase extra equipment to keep your plants safe. The additional equipment needed for HPS lighting also consumes energy and can significantly affect your electric bills.

Closing Thoughts

Indoor gardening has significantly risen in popularity. However, recreating the outdoor setup that most plants need to thrive can be challenging, especially concerning lighting conditions. This is where grow lights come in.

If you don’t mind forking out a bit more cash up front, grow lights are an excellent solution for providing plants light. However, as your collection grows, so will your lighting needs and electricity bills. Grow lights will increase your monthly bills, whether you go for LED or HPS lights, but in general LED lights are a good long-term investment.