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:
- BEST GROW LIGHTS FOR VEGETABLES
- Green Thumb Gardener
- BEST LED GROW LIGHTS INFO
- The 10 Best Grow Lights of 2020
- Best LED Grow Lights – Amazon
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:
- Chapter One – What Is Hydroponics and What Are the Benefits
- Chapter Two – Hydroponic Grow Media
- Chapter Three – Different Types of Hydroponic Systems
- Chapter Four – Let There Be Light!
- Chapter Five – Let My Plants Eat!
- Chapter Six – How to Build Your Own Hydroponic System
- Chapter Seven – Resources
- Chapter Eight Final Thoughts