How Much Does A Grow Light Cost To Run?

"How much does it cost to run my plant lights?"

A grow light is typically a specialist bulb that generates a lot of light energy to help your houseplants grow. It's natural to think they'd greatly impact your electricity bill.

It's true commercial growers with thousands of plants to take care of probably have huge electrical costs, but for the average indoor gardener, the monthly cost to run a moderately powerful single LED grow light can be as little as a dollar or two a month.

But how much does it cost exactly? Read on, and we'll work it out together and get some figures with our Electricity Cost Calculator freebie.

Table lamp light system with houseplants underneath

This small grow lamp is an efficient way to help my houseplants and brighten up my living room, especially during the dark winter nights.

The cost to run a grow light and what you'll ultimately end up paying for your electric bill will vary depending on three simple factors.

  • How long the light is used for each day.
    It might seem obvious, but a light that's on for 12 hours a day compared to one that's on for 6 hours will have double the energy usage.
  • How much power (Watts) the light draws.
    Some grow lights are fairly low powered, using as little as 10 watts in use. Others could easily draw up to 100 watts or more (ten times as much).
  • Your electricity rates.
    Electrical use is measured in Kilowatt Hours (kWh) and generally, a single kWh will have a set price. For example, in America, the average price of electricity in May 2022 was around 0.10 cents per kWh in Washington and 0.43 cents in Hawaii. This means it would be over four times more expensive to run the same grow light for the same period there.

All three factors are needed to calculate how much it costs to run your grow light. You can do the Maths yourself if you want a challenge. The formula to use is:

Total energy cost =
(Power in watts/1000) × hours operating × cost per kWh

Too much like hard work? Just input the data into our handy calculator below, and we'll do it for you and give you greater insight into costs per month and year.

Grow Light Electricity Cost Calculator

* Don't forget the decimal point! If you pay 25 cents per kWh, then you need to enter it as 0.25

Below are a few examples, with the assumption the light is on for an average of 8 hours a day and the user is being charged 0.25 per Kilowatt hour.

Watts Hours Per Day Price Per KWh Cost Per Month Cost Per Year
10 8 0.25 0.61 7.30
25 8 0.25 1.52 18.25
50 8 0.25 3.04 36.50
100 8 0.25 6.08 73.01
200 8 0.25 12.17 146.02
400 8 0.25 24.34 292.03
1000 8 0.25 60.84 730.08

A few examples to show how a bulb's wattage can make a huge difference. You don't need really powerful bulbs for good results.

So, is that more or less than you were expecting? Hopefully, you're pleasantly surprised, maybe so much so that you doubt what you're seeing. Don't be.

How do you find out the Watts a light bulb uses?
If you're struggling to complete this part of the calculator, then here are some pointers.

Certain equipment, especially LED grow lights, are very efficient and have substantial energy savings compared to traditional grow lights. The modern ones use less electricity, produce less heat and have a longer lifespan too.

On the flip side, perhaps the cost was more than you hoped. Here are some ideas for trying to reduce the cost. Firstly, the type of lighting can make a big difference. Old style high-pressure sodium lights or long fluorescent lights can be less efficient and cost more to run.

A better option could be to look at LED lights or a compact fluorescent lamp. Both tend to be smaller and use less energy.

Look at the wattage of the bulbs too. If you only have a few indoor plants that need the grow light, you can get powerful full light spectrum bulbs that draw 40 watts or less.

Further reading -
Trying to Save Money? Could using a low powered regular LED light bulb, be the answer?

You could also think about your setup. Do you have several bulbs to cover lots of houseplants in different areas of your home? Perhaps you're able to move the plants together to give the light coverage in one area of the room and use just one bulb instead of several?

What about the number of hours you're running the lights for? Could you run them for a few hours less a day? Your light fixtures may have generic or universal fittings and you could perhaps get energy efficient replacement bulbs that are still high quality but help reduce your monthly bill.


Questions and Answers

Are LED grow lights the best choice for cost savings?

In my experience, I'm going to say yes they are.

The older type of grow lights like High Pressure Sodium Light (HPS lights) or High-intensity discharge lamps (HID lamps) are still popular today. But they're less efficient, cost a little more to run (compared to what you get out of them) and can require unusual setups or specialist light fixtures.

In contrast, LED's are very efficient, don't produce a great deal of heat, and can be very adaptable, coming in regular bulb shapes or even as strip lights. LED Grow Lights will also be designed for purpose and give your plants the appropriate wavelengths they require for healthy growth.

How do I find out how many Watts a light uses?

Many appliances, including bulbs, will have information written on them known as a data plate, which includes the maximum power draw.

The photo below shows this information. You can also see that the watts are listed as a number followed by the letter "W", which you guessed it, stands for "Watt". In this case, the top bulb uses 36 watts and the bottom 8 watts.

A 36 watt bulb and a 8 watt bulb

The information in the blue circles shows the wattage of the bulbs, and from this you can work out what their electricity consumption will be.

If this information is missing, you could contact the manufacturer or try and review where you brought them from initially, as the website listing or shop may be able to give you this information.

The last option is to use a special device to measure power draw. Generally, these meters will plug into your power outlet and then you put the device's plug (in this case, your lamp) into the meter. It then measures energy use.

I use a Smart Plug from TP-Link that shows me the actual power draw of a light. It has the added advantage of being controllable by an App or your voice if you have a Smart Home setup, giving me greater control over how I use my grow light.

If you want to take a look here, it is on Amazon. (Bare in mind this is an affiliate link and we may earn a commission from Amazon if you buy one. Of course, you don't have to get this one or even buy it from here, but you'll get an idea of how they work).

Are indoor grow lights worthwhile?

If you want to try growing plants in low light areas or you just generally want to give your houseplants a boost, then I think grow lights are seriously worth thinking about.

They don't have to cost a considerable amount to buy for general use; additionally, you can get some, with fairly low running costs.

Full spectrum grow light with a Chinese Evergreen growing below it

Grow lights can be an easy and cheap way to get your indoor garden flourishing wherever there isn't enough sunlight from windows or other light sources.

How many hours a day should grow lights be on for?

This tricky question will require more than a few sentences to answer. We're writing a complete grow light guide that will cover this, though. Watch this space!

Let's Sum up

Most indoor gardeners will be using relatively low powered grow lights. If you only have one or two and are using a modern LED light it could add just a few dollars/pounds etc, a month to your total power bill. In the grand scheme of things, for many people, this isn't a lot of money for a thoroughly enjoyable hobby.

It may even save you money in the long run, because you won't need to keep going out every few months to buy new houseplants to replace the ones that didn't make it due to insufficient natural daylight.

Your electricity rate is important.
The price that you pay for your electricity can really help to save money in the long run. Check with your provider regularly to ensure you're on the best deal for your circumstances.

Extensive setups or a more powerful led light will increase your daily expense because your electricity usage will go up.

If your setup has a high power consumption, see if there are things you can do to reduce how much energy you're using.

In summary, the cost to run your grow light will depend on three simple factors. The number of hours you use your light for, the amount your energy provider is charging per kWh and the amount of power your device uses.

Our calculator will work out your typical running costs per day, each month and over an entire year. Give it a try and let me know your thoughts and if it was helpful.

About the Author

Tom Knight

Tom Knight

Over the last 20 years, Tom has successfully owned hundreds of houseplants and is always happy to share knowledge and lend his horticulture skills to those in need. He is the main content writer for the .

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