How Many Lumens do Plants Need?

Lumens do Plants Need

The increase in indoor gardens has led people demanding to use of grow lights to support. That’s because indoor gardens don’t have access to direct sunlight. The grow lights act as a direct source of light.  So, how many lumens do plants need? 

There are different grow lights for different plants. A small plant uses fewer lumens compared to a big plant. At the same time, a sun plant requires more lumens than a low-light plant. So, to know the number of lumens plants need, you will have to consider the type of plant you are growing. 

A sun plant requires a minimum of 3000 lumens to start the seeds, then in the flowering stage to maturity, and it will require a minimum of 5000 to 10000 lumens, depending on the plant. 

What is a lumen?

Lumen is the amount of light a bulb or light source emits. You can equate it to the brightness of the bulb. The brighter the bulb, the more lumens it contains. 

So, can you compare lumens to watts? 

Lumens do Plants Need

No! Lumens and watts are two different things in a bulb. Lumen is the amount a light produces, while watts is the amount the light consumes (the measure of energy consumed). That’s why you see LED lights have fewer watts than traditional bulbs. LEDs are known as power-saving lights. 

For instance, a 6W LED light can have the same lumens as a 50W bulb. The lumens plants need can come from any bulb as long as it provides the required amount. 

How many lumens do plants need?

Before you speak of the lumens plants need, start by identifying the type of plant you are growing and its conditions. Determine the number of plants you have, the total area of the garden, the stage of development, and their growing height. 

Once you know that, look at the color spectrum and how it affects plant growth. The color spectrum is important because grow lights come in different colors. 

Color Spectrum

The color of your light can affect your plant growth negatively or positively. Just look at it as the sun; it provides different colors. You have seen it from a rainbow’s perspective, where it shows the different colors the sun produces. 

Lights are measured using wavelengths because each wavelength serves a different purpose in plant growth. These wavelengths provide lumens plants need to grow. But some wavelengths are different and less important than others. 

For instance, wavelengths 400 to 700 are important since they provide lumens plants need during photosynthesis. As a result, this spectral region is generally known as PAR, “Photosynthetically active radiations.” 

PAR is measured in micro-moles per second. You can measure them using a quantum sensor. This device measures light intensity by considering the number of photons a light produces in a second. 

You can check out the different colors in a grow light to understand what they mean and which are best for plant growth.

What amount of lumens do plants need to grow?

As you have seen, a full-sun plant requires more lumens than medium or low-light plants. So, to answer your questions about how many lumens do plants need, see below. 

Sun plants need a minimum of 3000 lumens to grow seeds and a minimum of 7000 to grow the plant in the flowering stage. For instance, a tomato plant likes full sun. To grow it indoors, you need a grow light that can produce at least 3000 lumens from the seeds to germinate. Anything less than that, the seeds won’t germinate. After germination, the lumens plants need 7000-7500 to support their growth. It will need 10000 lumens to produce the ripe red tomatoes to flower properly.

On the other hand, medium plants require at least 5000 lumens per square foot to get the best amount of light. You can start the plant from lower lumens when it’s germinating, but then increase the lumens plants need as it continues to mature. As it starts to flower, ensure it has at least 7000 lumens. 

For plants that require low light, provide them with at least 2000 lumens per square foot when growing seedlings. As the plant grows, provide it with 5000 lumens. Even though this amount of lumens seems too low for a plant to mature, it’s much when it comes to a low-light plant. 

The lumens plants need are calculated per square foot. So, if you have a small room with plants, make sure that you calculate the number of plants in the square to ensure each plant receives an equal amount of light. 

Grow lights Lumens Chart

Since some bulbs don’t show the number of lumens they produce, we should provide you with a chart showing you the lumens a bulb can produce. The table differentiates LEDs and incandescent bulbs. 

Lumens (lm)Incandescent (W)LED (W)

From the chart, you have seen that the higher the amount of watts a bulb has, the more lumens it contains. 

How many lumens do seedlings need?

Most gardeners prefer to grow their seedlings indoors before moving them outdoors. That means you need to provide them with light so that they can germinate. Giving them excess light can burn them, and if they get too little light, they won’t have the energy to grow. 

So, knowing the correct amount of lumens plants need to grow is important. The minimum amount of lumens plants need per square foot is 2000 to 3000. This can work for seedlings from full, medium, or low-light plants. You can increase the number of lumens for a plant, but this is the minimum requirement you can start with.


How long should a plant receive light?

If you use a grow light, provide your plant with at least 14 to 18 hours of direct light. This works best for vegetables and flowering plants. Some plants, such as Begonias, Kalanchoe, and Chrysanthemum expose to light for 12 hours a day. 

Can an LED light provide sufficient Lumens compared to an LED grow light?

An LED light can’t provide the same amount of lumens as a grow light. That’s because the LED grow light is made with a wide spectrum of colors important to plant growth. The normal LED light is made for illumination only. 

Can grow lights lumens hurt my eyes?

Yes. Grow lights are made with extra bright UV rays; since UV rays are dangerous, they can hurt your eyes. Blue lights are common for disrupting brain activity and sleep patterns. So, avoid looking directly into the grow light. 

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