Hydroponic growing indoors requires that we emulate the conditions our plant would typically experience outdoors. This includes providing the right amount and duration of light to keep the plants thriving. Grow lights are the answer, but what types of grow lights do you need?
The best grow lights for hydroponics are full-spectrum white light grow lamps, or LED grow light systems with adjustable red, blue, and white light options for the different growth stages of your plants. The duration of light for indoor hydroponics is between 10 and 18 hours, depending on the plant.
Plants require a specific light spectrum range to convert the nutrients they absorb through the roots into usable food. Sunlight provides the right light spectrum range, but for indoor hydroponic growing, we must be selective of the types of light we provide.
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Pro tip: I really like this 45W LED grow light panel made by AeroGarden, available on Amazon. (Ignore the photo on the listing. Not sure why that’s there! The actual light is a tabletop panel that swivels, so you can tilt it to provide light right where you need it. )
Types Of Grow Lights for Hydroponics Lighting
Plants need light as an energy source to help them convert nutrients to food, stimulate growth, and encourage fruiting.
This is particularly true of vegetables that thrive in direct sunlight and typically require 6 to 8 hours of direct sunlight each day. Plants also react to light duration, which outdoors indicates seasonal changes to the plants and triggers certain processes.
Longer hours of light indicate the approaching summer growing season, while light duration becoming shorter indicates the approach of the dormant winter season.
In the outdoors, direct sunlight provides everything the plants need in the correct ratios to keep them healthy, growing, and productive.
Proving the Right Type and Quantity of Light
Sunlight is called white light and contains a mixture of all the color spectrums to produce white light. Sunlight also contains light in spectrums that humans cannot see, such as infrared light.
When growing plants indoors, we need to provide the right type and quantity of light to give our plants the energy they need for all their internal processes.
Normal light bulbs that we use in our homes do not generally contain the right ratio of light spectrums at the right intensity level to help our vegetables grow. Some have too much red and not enough blue light, while others have too much blue and muted red, giving us shades of white light.
So how do you know what hydroponic grow lights are best to use indoors for your plants?
What Grow Light Spectrum Is Good for Hydroponic Lighting?
Plants use more or less of certain light wavelengths at various parts of the growth stages. White light is ideal because it provides all the light spectra, and the plant uses the ones it needs at each growth stage.
When providing artificial lighting, many hydroponic growers offer single-color lights to stimulate processes in the plant and encourage growth.
The light spectrum is denoted by wavelength, or nanometers, abbreviated to nm. Many light manufacturers indicate their light bulb color in color temperature, or Kelvin, abbreviated to K. This metric for white light bulbs is important for hydroponic growers.
While plants use the full light spectrum to some degree, the most important for the plant are far-spectrum red light in the 700nm to 800nm range, red light in the 600nm to 700nm range, and blue light in the 400nm to 500nm range.
Light Spectrum Ranges
What do these light spectrum ranges do for plants grown in hydroponics?
- Red light spectrum from 700nm to 800nm. This light spectrum promotes photosynthesis in plants and is ideal for plants in the growth stage. It is also the light spectrum needed when the plant is flowering and fruiting.
- Far-spectrum red light from 700nm to 800nm. Light in this spectrum is close to infrared and stimulates leaf size growth. Larger leaves mean more light can be absorbed, and the plant can grow faster and larger.
- Blue light spectrum from 500nm to 600nm. Blue light stimulates sturdy, solid structures in plant stems, preventing the plants from becoming leggy and falling over.
- Violet light from 400nm to 500nm. This light spectrum is ideal for seed germination, which can be changed to blue light for seedlings.
Some light bulb manufacturers only rate their products with the Kelvin, or K designation, which requires some conversion to the nanometer range for hydroponic growers. This is particularly useful when you are using white light as grow lights.
The shades of white light or the color temperature in Kelvin will indicate which wavelength has the bias in the white light. Cool white generally has a more blue light, while warm light has more of a red light component to it.
The Best White Light Temperature for Plants
The following lighting table will help you choose the best white light temperature for your plants.
|White Light Color Temperatures|
|Cool White||6000K – 7000K||Blue Bias (400nm to 500nm)||Best for vegetative or growth stage (seedlings)|
|Day White||5000K – 6000K||Emulates noon daylight||Used as a full spectrum light for all plant growth stages|
|Warm White||2000K – 3000K||Red Bias (500nm to 700nm)||Best for flowering and fruiting stages of plant growth.|
When using white light in hydroponics, I prefer the 5000K to 6000K light bulb, which resembles natural full-spectrum light. These bulbs are generally cheaper and more readily available, and the plants will use the light spectrum they want from the light source.
Advantage Of LED Lights for Hydroponic Grow Lights
Pro tip: I really like this 75W LED grow light that’s available on Amazon, because you can adapt the distance of the light based on the growth stage of the plant.
Hydroponic LED grow light options are great because they use less electricity and do not produce heat as a side effect of the light being produced.
LED lights are relatively new in the hydroponic lighting world, but they have positively impacted indoor hydroponic growth.
LED lights are cheaper and more cost-effective to run than most traditional hydroponic lights. LED lights are easily available and reduce the risk of fire when used in grow tents.
When Is Sunlight Not Enough for Indoor Hydroponic Plants?
You may have a sunny room or window ledge that receives good morning or evening sunlight, but is this enough to provide energy for your plants?
The sunlight coming in from the windows comes in from a specific angle, and the duration of the light is generally insufficient for successful hydroponic growing.
The angle of the sunlight will cause the plants to lean over to one side and promote leggy, weak growth, especially in seedlings.
The duration of direct sunlight through a window is generally insufficient for the plant’s needs. As the sun moves higher in the sky, the intensity of the light coming in through the window is reduced and does not meet the requirements for plants, especially vegetables.
Pro tip: If you want to use light from a window, consider using this window shelf and this microgreens kit, both from Urban Leaf. Microgreens don’t require as much light, and the microgreens kit fits perfectly on this shelf. I’ve successfully grown microgreens in my north-facing window using this set up.
Hydroponic grow lights provide a constant, full-strength light from above, and you can control the duration required for the types of plants that you grow.
Some established plants can be grown in a room with a south-facing window in the northern hemisphere, as the light intensity of morning light is higher than afternoon or evening light. This would be better for vegetable plants as they need this type of light to flourish.
Certain house plants that do not require intense light can be grown in south-facing windows and will benefit from the less intense late afternoon sunlight.
How Much Lighting Do Your Hydroponic Plants Need?
Plants need different light exposure durations to grow well and produce sturdy growth in an indoor hydroponic environment.
Light intensity for hydroponic lighting is an important metric to consider. The light intensity of grow lights is indicated in PPFD, or Photosynthetic Photon Flux Density. Most grow lights will have this rating indicated on their packaging.
The PPFD rating is usually between 100 and 1500 or more, with the upper end of the scale being a more intense light. You can opt for more intense light and manage the light intensity with the distance the light is placed above the plants.
If the light is placed closer to the plants, it will be more intense and less intense further from the plants.
Most fruiting-stage vegetable plants require a PPFD of between 600 and 900, while growth stages require between 400 and 600 PPFD. Seedlings do well with lights of between 200 and 400 PPFD ratings. This intensity can be adjusted with the plant’s distance from the grow light.
Hydroponic Vegetable Light Requirements
Most hydroponic vegetables require certain light durations for optimal growth. The following table summarizes the light requirements for some hydroponic vegetables and herbs.
|Hydroponic Vegetable Light Requirements|
|Lettuce||14 to 16 hours||100 – 250|
|Tomatoes||12 to 16 hours||500 – 600|
|Swiss chard||10 to 18 hours||100 – 250|
|Basil||10 to 12 hours||100 – 250|
|Cucumber||12 to 16-hours||500 – 600|
|Herbs||12 to 16 hours||100 – 250|
The Easiest Grow Light Option for Indoor Vegetables
If you simply want to push the easy button when it comes to growing vegetables indoors, I recommend investing in AeroGardens. I personally have about 20 AeroGardens. They are a bit pricey, but they are also foolproof. They provide the exact right amount of light for the right amount of time without any effort on your part. Finally, they also let you know when to add water and nutrients.
Here are the different AeroGarden models that I personally own, all available on Amazon:
- AeroGarden Sprout – 10″ grow height, 10W light
- AeroGarden Harvest 360 – 12″ grow height, 20W LED grow light
- AeroGarden Harvest Basic – 12″ grow height, 20W LED grow light
- AeroGarden Harvest Elite – 12″ grow height, 20W LED grow light, more bells and whistles than the Harvest Basic
- AeroGarden Harvest XL – 18″ grow height, 25W LED grow light
- AeroGarden Bounty Basic – 24″ grow height, 30W LED grow light
It may seem a little complicated when you first start organizing lighting for indoor hydroponics, but it is not as challenging to understand as it sounds. Many vegetables have similar lighting requirements, which means you can group certain plants together for optimal results.
If you are new to indoor growing, choose simple hydroponic lighting such as a full spectrum 5000K to 6000K light or an inexpensive LED grow light system to experiment with for your lighting requirements.
Here are the sources I used in writing this article:
- My personal experience 🙂
- University of Minnesota Extension
- University of Florida
- Oklahoma State University Extension
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