How Much Does A Grow Light Cost To Run A Month?

Running grow lights, whether for a small indoor garden or a large commercial setup, is a key part of indoor gardening. Although it’s exciting, it’s also a bit scary to consider the mounting cost of your garden, and you may specifically ask: How much does a grow light cost to run a month? My small grow light is 250w at 50% dim, 10 hours per day at 0.11 cents per KWh costs about $4.19 per month. But each variable mentioned changes the cost to run the light, plus ther are some other factors you should consider to realize the true full costs.

250w LED light at 50% dim

Understanding Grow Lights

Before we delve into the cost aspect, it’s essential to understand what grow lights are and why they are vital in indoor gardening. Grow lights are specialized lights designed to support plant growth by providing a light spectrum similar to sunlight. They are particularly beneficial for indoor plants, enabling them to thrive even in the absence of natural light.

Grow Light Types and Their Impact on Cost

Grow lights are available in several types, including HID (High-Intensity Discharge), fluorescent, and LED (Light Emitting Diodes). Each type has a specific power consumption rate, which impacts the cost of running them. For instance, LED grow lights are often more energy-efficient than HID and fluorescent ones, meaning they consume less power, translating to lower running costs.

The Cost Calculation: Breaking Down the Factors

The cost of running a grow light depends on several key factors:

  1. Type of Grow Light: Different types of grow lights consume power differently. LED grow lights typically consume less power compared to HID and fluorescent ones.
  2. Wattage: The power a grow light uses, measured in watts (W), directly impacts the running cost. A higher wattage means more power consumption, which results in a higher cost.
  3. Duration of Usage: The number of hours a grow light is used per day significantly affects the cost. More hours equal more power consumption, hence a higher cost.
  4. Electricity Rate: This is the cost per unit of electricity, which varies depending on your location and electrical company.

The Math Behind the Cost

To calculate the cost of running a grow light, you need the wattage, hours of usage, and electricity rate. The formula is:

Total cost = (Wattage/1000) x Hours of operation x Cost per kWh

For example, if you use a 1000-watt grow light for 12 hours a day, with an electricity rate of 10 cents per kWh, the cost per day would be:

(1000/1000) x 12 x 0.10 = $1.20 per day

To calculate the cost per month, multiply the daily cost by the number of days in a month. Using the above example, the monthly cost would be:

$1.20 x 30 = $36 per month

Radish root system thriving under indoor light

The Impact of Grow Room Size

The size of your grow room or tent also plays a role in the cost of running grow lights. A larger area will require more lights, leading to higher running costs. Likewise, the initial cost of purchasing the grow light system varies depending on the type and size of the system.

LED Lights: A Cost-Effective Choice

While LED grow lights might have a higher initial cost compared to HID and fluorescent ones, they offer long-term savings due to their energy efficiency and longer lifespan. They use less power and have to be replaced less often, making them a cost-effective choice in the long run.

Making the Right Choice: Considering Plant Needs and Coverage

When choosing a grow light system, consider your plants’ specific needs and the size of your grow room or tent. Different plants have varied light requirements, and selecting a grow light that offers the appropriate light spectrum is crucial. Also, ensure the grow light provides enough coverage for your entire grow room or tent.

In conclusion, the monthly cost of using a grow light for indoor growing can vary significantly based on several factors. By calculating these costs, you can estimate the monthly cost of running your grow light setup. While there is a cost associated with running grow lights, choosing an energy-efficient system and monitoring usage can help manage these costs effectively.

The Cost of Running Different Types of Grow Lights

Let’s assume you’re running the lights for 12 hours a day a typical flowering cycle, and your electricity cost is 0.18 per KWh about the national average today according to google.

The monthly and annual costs for some common grow light wattages:

WattsHours Per DayCost Per KWhCost Per MonthCost Per Year

The Cost to run the light my radishes are currently growing under, a 250w LED light I keep at 50% dim, at Portland’s electricity cost of 0.11 per KWh, would be about 0.33 cents per day.

Ways to Lower Your Grow Light Costs

There are several ways to reduce your grow light costs. These include:

  • Switching to more efficient LED grow lights: LED lights are more energy-efficient and long-lasting.
  • Using grow lights during less expensive periods of the day: If your electricity provider offers time-of-use rates, you can schedule your grow lights to run during off-peak hours when electricity is cheaper.
  • Reducing the number of hours grow lights are on: Experiment with the number of hours your plants need light and adjust accordingly.
  • Using natural light when available: If you have access to natural light, make the most of it and turn off the grow lights when not needed.

Are 8 Hours of Grow Light Enough?

Whether 8 hours of grow light is sufficient depends on the type of plants you’re cultivating and their specific growth requirements. Many plants undergo different stages of growth, including germination, vegetative growth, flowering, and fruiting, each with varying lighting needs.

For seedlings and young plants in the vegetative stage, 8 hours of grow light can often be adequate. During this phase, plants focus on developing robust foliage, and a standard photoperiod of 16 to 18 hours of light per day is common in controlled environments like indoor gardens.

However, when transitioning to the flowering or fruiting stage, many plants benefit from longer light exposure, typically requiring 12 to 16 hours of light daily. Some high-light-demanding crops, like tomatoes or peppers, might even benefit from up to 18 hours of light to maximize yields.

Furthermore, the intensity and quality of light matter just as much as the duration. Plants need the right spectrum and light intensity to photosynthesize effectively. LED grow lights, for instance, can provide the necessary spectrum while being energy-efficient.

So while 8 hours of grow light might suffice for certain plants during specific growth stages, it’s crucial to tailor your lighting duration to your plants’ developmental phases and specific light requirements. Understanding the specific needs of your crops and providing them with the appropriate light conditions is essential for achieving healthy growth and optimal yields in indoor or controlled environments.

Hydroponic Radishes almost ready to harvest

Is it Cheaper to Run Grow Lights at Night?

The cost-effectiveness of running grow lights at night hinges on a few key factors. Electricity rates during off-peak hours, which typically include nighttime, tend to be lower in many regions. This can make running grow lights during the night a more cost-efficient option if you have flexible control over your lighting schedule.

However, it’s essential to consider other variables such as your specific electricity provider’s rate structure and any additional costs associated with nighttime operation, like the need for cooling systems to offset increased temperatures during the day.

Additionally, certain plants may have specific light and dark period requirements for optimal growth, so it’s important to align your lighting schedule with their needs while considering the cost-saving potential of nighttime operation.

Remember, indoor gardening comes with costs, but the joy and satisfaction it brings are priceless. With a bit of planning and wise choices, you can enjoy your indoor garden without breaking the bank.


Located in Portland, Oregon, Tim started gardening in his 20's and after a couple of decades felt like he had some things to share.

Recent Posts