Is Hydroponics Without Sunlight Possible?

Thomas Angas by Thomas Angas | Last Updated: January 16, 2021

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Hydroponics is a fantastic method for growing plants, you’re responsible for everything within the system which means that you can optimise your setup to produce the best harvest possible.

One common question that many new growers have about the setup is around lighting and understanding if hydroponics without sunlight is possible.

So today that’s what we’re going to take a look at.

Let’s get started!

Is Hydroponics Without Sunlight Possible

Is Hydroponics Without Sunlight Possible?

This is a pretty simple answer, hydroponics without sunlight is possible, however, it does have certain challenges that you need to understand to get the most from your hydroponic system.

What Plants Need To Grow

So now we’ve established that it’s possible, next we need to understand what we can do to replace natural sunlight in your system but first it’s worth understanding what plants need to grow.

There are five key things that plants need to grow:

  1. Light
  2. Air
  3. Water
  4. Nutrients
  5. Space to grow

Within our systems we aim to provide our plants with optimal levels of each, but while air, water, space and nutrients are fairly easy to provide – replacing the sun is tricky.

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How Light Affects Plant Growth

Plants use light as a source of energy through a process called photosynthesis.

Photosynthesis takes place in the part of the plant cell containing chloroplasts, these are small structures that contain chlorophyll. For photosynthesis to take place, plants need to take in carbon dioxide (from the air), water (from the ground) and light (usually from the sun).

Without sufficient light, plants aren’t able to make enough energy so don’t grow properly.

However, as you’re about to find out, you can’t just put a plant in front of a convention light bulb and expect it to grow.

Why the Light Spectrum is Important

To get plants to grow properly indoors you need to use a light source with the right light spectrum.

Visible light, that is light that the human eye can see falls between the wavelengths of 390 – 700 nanometers.

It’s easy if you think of the light spectrum as a colour band starting with purple on the left and red on the right, similar to the image below:

light color scale

Blue Light Spectrum 400-500nm

When plants are in their growing stage, they use the light from 400-500nm which is packed with energy, this is known as the plant being in a vegetative state.

When plants don’t get enough blue light in their early stages of development, they grow weak and have yellow streaks in the leaves rather than green.

So if you’re starting seeds indoors, it’s important that your light is heavy with blue light.

Red Light Spectrum

During the flowering stage of your plants development, they will use the lower energy red part of the spectrum between 650nm and 730nm.

If plants don’t get enough red light, they aren’t able to flower properly.

Keep These Things In Mind

So if we’re aiming for hydroponics without sunlight then we need to ensure we’re using a grow light that is able to provide your plants with both sufficient quantities of blue and red light which traditional lighting can’t provide.

This is where specialist grow lights come in.

Grow Lighting

As we wrote in our hydroponic lighting guide, there are three main types of hydroponic grow light to choose from:

High Intensity Discharge (HID)

These are incandescent lamps that are very popular with indoor growers. Typically they are available in High-Pressure Sodium which contains more red light and Metal Halide which contains more blue light.

The downside of HID lighting is that they produce a lot of heat and require a lot of energy to run which is why they’re mostly used by commercial growers.


These lights produce significantly less heat than HID lamps, however, they are more focused on the blue light spectrum so can be used to start a plan but you’ll need an additional red lamp to make it flower.


LED is fast becoming the go-to choice for both commercial and domestic growers. They are low cost to run, produce little heat and panels can be designed to include both red and blue light so you just need one panel to cater for your plants development.

The Bottom Line

So there you have it, hydroponics without sunlight is entirely possible, in fact for many growers it’s the best choice as it allows them to completely tailor the lighting requirements of the plants each stage of development.

Thomas Angas, the founder of Authority Gardening lives with his wife and two darling pups. He spends his free time writing, hiking and learning how to become a better gardener. He launched Authority Gardening in 2017 to help people all over the world their gardens grow.