Let There Be Light! Hydroponic Lighting

LIGHT – Plants Got to Have It. 

Plants need the right kind of lighting to thrive.   Plants with any fruit or flowers require 4-6 hours of direct sunlight and at least 12-14 hours of very bright light per day. If you don’t have an outdoor space, or you live in a climate that has a short growing season, indoor hydroponic gardening is the best approach.

For hydroponics lighting there are three main types:

  • Compact Fluorescent Lighting(CFL)
  • High-Intensity Discharge (HID), which includes both High-Pressure Sodium (HPS) and Metal Halide (MH) bulbs
  • Light-Emitting Diode (LED)

Key considerations – yes you need light, but only buy what you need.  Make sure you get the right spectrum of light.

Types of Lights

Today, the most widely used lights for professional use are HIDs and fluorescents. Indoor flower and vegetable growers typically use high-pressure sodium (HPS/SON) and metal halide (MH) HID lights, but fluorescents and LEDs are replacing metal halides due to their efficiency and economy.

While easy to find and install Fluorescent lights generally don’t last as long as LEDs are not ideal for fruiting and flowering plants. Modern fluorescents, however, have increased the lumen output, can be found as compact bulbs and are now being designed to last longer than their predecessors.

How Much Light

So how many Watts do I need?

We recommend first figuring out the square footage of the area you are trying to light. For high-light plants like tomatoes – around 40 watts per square foot for is optimum. For low light plants such as small leafy plants like herbs and lettuce 25 to 30 watts per square foot is all that is needed.

You will need to determine what you really.  What you need to cover is just the area that your plants will take up will be grown not the whole room size.     Here is some math to help you determine the Watts you will need.

  • Growth Area – Width x Depth = Square Feet, e.g. 2 x 2 = 4 sq. ft.
  • How much light is needed – Watts x Square Feet = Desired Wattage, e.g. 40 x 4 = 160 watts.
  • You will need a bulb or combination of lighting that equals 160 – 200 Watts.

LEDs For the Beginner

For someone that is just starting in Hydroponics, we recommend LEDs.  To work well an LED grow light should be more than 32 watts per square foot of grow space, but for optimum results, it should be over 50 watts, up to 80 watts.

Look for lights that produce full-spectrum light, which is best at replicating real sunlight.   LED Lighting that already comes with fixtures or hanging hooks for easy positioning is always a plus.

 Reflector and Venting

A reflector is the most important part of a grow light system, especially if you are using a bulb. It helps to reflect the light to the plants and makes the light coverage more uniform.   You want the light to be distributed evenly over the entire growing area. Horizontal reflectors are the most efficient reflectors and are the most popular. LEDs only put out light in 180 degrees or less, so they normally don’t need reflectors.

Please keep in mind that you might need venting (fan) for lighting systems that or putting out heat.   You don’t want to cook your plants before they are out of the pot. Another advantage of LEDs is that they run cooler and venting is not as much of concern.

Which LED Should I Buy?

There are hundreds of LED grow lights for sale.  The Chicago Tribune January 2020 publish an online article entitled “BEST LED GROW LIGHTS”.  Check it out, it will be helpful in choosing the right LED system to meet your needs.

Other resources are:

Other resources to look at.  Very nice overview of what you need to consider.

Finally, the definitive answer does double watts equal double yield?   From Jebb Gardener – recommend subscribing to both of these channels for some very helpful info and in the case of Jebb some good laughs.

Check any of these Chapters in our Complete Guide to Hydroponics.   We look forward to your comments and suggestions on how to improve this guide:

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  1. I bet hydroponic lighting is a gardener’s paradise. I new plants needed sunlight but didn’t know LED lights grow lights were even out there and more importantly it’s the right kind of light. Not only are LED lights more efficient it seems like plants thrive on them to grow!

  2. I think LED lighting is the best way to go as like you say they last for ages.
    I have never took up indoor gardening but it sounds a great idea if you have not got a garden.
    Is it easy to grow vegetables indoors using indoor hydroponic gardening?
    Interesting post. Thanks.

    • Definitely LED lighting is the way to go, considering how long a bulb lasts – it is very cost-effective. As for vegetables – that depends on how crazy you want to go. Most start with simple herbs or lettuce then move on to others such as cherry tomatoes. Start simple and small then go from there. There are plenty of inexpensive kits out there you could try and see if hydroponics is for you. Thanks again for visiting the site….

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