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Not all LEDs are created equal. Scientific discoveries have brought the cost of LED lighting down and there is a constant stream of new products on the market. The lines between grow lights and other types of lighting have become blurred. It is important to understand the subtle differences in order to provide the best lighting for your plants.
There are several differences between LED lights designed for human consumption and those designed to promote plant growth and development. These differences can be measured in terms of intensity, the color spectrum, and the light footprint.
It is possible to use LED lights that were designed for the office, garage, or even your home, as grow lights. They will even achieve similar yields to those produced by grow lights. However, there may be subtle variances in photosynthesis that affect the taste and appearance of food crops.
The history of LED lighting
Sunlight was humanity’s first light source. The harnessing of fire liberated us from the rhythms of day and night. It was made portable by carrying lit torches around after sundown. Oil lamps and gas lights followed.
The first electric light was produced in 1879 when Edison caused a filament to glow by passing current through it, without destroying it. The challenge then became how to develop a filament small enough to fit into a glass bulb, and robust enough to last for a viable length of time. This incandescence was an inefficient process as 90% of the energy needed to generate light, turned into heat. However, it has served humanity well until the present day.
Lights that used encased gases followed in the first half of the 20th century. These include mercury vapor, halogen, and fluorescent lights. There were gains in light intensity and less power was lost to heat. When scientists learned how to bend fluorescent tubing, more light could be produced in a more compact space, hence the term Compact Fluorescent Lighting (CFL).
Real savings in energy efficiency came with the invention of Light Emitting Diodes (LEDs). These tiny diodes made use of a process called electroluminescence. In certain crystals, the flow of electrons results in photons that produce light.
The minuscule amount of light emitted was magnified without wasting significant energy in the form of heat. The ratio of light to heat was 9:1 so there was no longer a need for the light to be encased in glass. LEDs have a much longer lifespan than other artificial light forms.
At first LED lights were infrared, and were used commercially in remote controls. Then, visible red, followed by green lights were produced and little indicator lights on appliances became ubiquitous.
The real breakthrough came in the 1980s when blue LEDs were produced. When these were combined with the other LEDs on the spectrum, ‘white’ light was produced. These can be found in smartphones, street lights, and increasingly home, office, and grow lights.
The price of LEDs dropped steadily and more manufacturers entered the market. The main players continued to innovate. Today we have chip-on-board, surface-mounted, and quantum-board LED lights, among others. They have different properties, making them suitable for different applications.
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LED Grow Lights – an overview
Grow lights are used to simulate sunlight, and thereby stimulate various plant processes, such as photosynthesis, flowering, and fruit production. Plants vary, but some are able to withstand far more exposure to sunlight than humans.
Grow lights were designed to match the intensity of light required. When LED lights became bright enough and sufficiently cost-effective, they grew in popularity because they use far less power and produce negligible amounts of heat.
Early research determined that the leaves of plants primarily use the blue and red portions of the electromagnetic spectrum. So purple or ‘blurple’ lights were developed that emitted only those two colors. It is true that foliage flourishes under blue light and flowering and fruiting is triggered by the colours on the red end of the spectrum.
However, further research discovered that plants use the entire electromagnetic spectrum, at various stages of their development, including the rays that are invisible to the human eye. Consequently, ‘white’, full spectrum grow lights were developed, which produce light that is closer to sunlight.
LED grow lights were initially significantly more expensive than other forms of lighting, which detracted from the lower running costs. These prices have dipped as more manufacturers took advantage of cheaper LEDs and a growing demand for indoor lighting for plants. Brand awareness became important as less scrupulous manufacturers used inferior processors.
Scientists continued to experiment with light intensity, composition, and design. Some lights allow users to control the intensity and change the spectrum of light emitted. A recent innovation has been the quantum board which distributes the light more evenly across the surface of the grow area, otherwise known as the footprint.
How LED grow lights differ from other LED lights
There are four main differences between LED grow lights and those developed for other purposes, namely intensity, spectrum, footprint, and proximity.
Plants that are typically grown indoors can tolerate a greater intensity of light than humans can under similar conditions. If we are exposed to full-spectrum sunlight, our skin burns and our eyes hurt. Long-term exposure to optimum grow lighting can cause irreparable damage to both.
If plants are supplied with inadequate amounts of light they will become leggy as they strive to get closer to the source. In edible crops, such as microgreens, this results in light, less nutritive dense leaves, and a more woody taste.
In indoor plant production, the light can be manipulated to meet the needs of the plant. For example, if you wish to grow leafy plants or microgreens, where foliage is more important, blue or ‘white’ light is needed.
Although this light has become prevalent in modern living, overexposure has a detrimental effect on our eyes and our melatonin production, which controls our sleep/wake cycle and moderates our immunity levels.
Red light, which stimulates flower and fruiting in plants, induces drowsiness in humans and is used to treat patients with insomnia.
The footprint of a light can be mapped. Usually, the light intensity is greatest directly underneath the center of light, with diminishing levels further away. The quality of a grow light can be determined by measuring light levels across its footprint.
Plants that are furthest from the center will receive significantly less light. Growers can use this space to grow plants that require less direct sunlight than those that they would place at the center.
If you are only growing only one crop, the distribution of the light needs to be more even. Quantum boards which spread the individual LED lights out more, seek to improve the quantity and quality of light distribution across the footprint.
Humans are mobile and far more adaptable to light levels. We can move closer or farther away, according to the light intensity in an area. We tend to operate with fewer lights at home, at work, or in other venues. They are hung several feet from our heads and therefore create a larger footprint of less intense light.
Typically, plants are grown in a confined area indoors. In order to achieve the required light intensity, an artificial light source needs to be within a few feet of the plant and should be raised as the plants grow.
Humans can tolerate this close proximity for tasks or mood lighting, but consistent exposure would strain our eyes.
Can you use any LED lights as grow lights?
Ordinary light fittings can be used if you are experimenting with growing plants indoors, or have a small indoor plant set up. You can achieve higher light levels by placing the lights close to your plants and using mirrors and other reflectors. The color spectrum, likewise, can be manipulated by using a combination of colored LED lights.
You will need to pay attention to the plants’ needs and regularly monitor their health.
If your plants are vital for food production or a commercial venture, it makes more sense to invest in the most appropriate grow lights for your requirements. For information on how to calculate running costs, follow this link.
Adequate lighting will keep your plants alive but optimal lighting will make them thrive. Grow lighting has been raised to an art form. If your plants lift your mood on a wintry day or provide your family with fresh, tasty food, they will appreciate the best lighting you can give them.
Check out these must-have gardening products
You don’t need much to start gardening, but some tools and products will make a difference in how comfortable and effective gardening can be for you. Here are my favorites:
- Garden Trowel. A good garden trowel will last you many years. I love how sturdy this hand trowel from WOLF-Garten is, the metal doesn’t bend and it has a nice grip.
- Trimming Scissors. I use them for delicate pruning and harvesting all summer long, and they’re super handy. These Teflon Trimming Scissors are extra nice because they don’t rust as easily.
- Dutch Hoe. Dutch hoes may seem old-fashioned, but there’s nothing like a quick sweep through the topsoil to get rid of small weeds – no bending required. I love WOLF-Garten’s selection: this dutch hoe coupled with their universal handle.
- Grow Lights. These grow lights from Mars Hydro are super strong, yet dimmable, so they fit every stage of growth. They don’t put out too much heat and are very economical.
- Seedling Trays. There’s an art to choosing the best size for seedling trays so that it holds the perfect amount of water and gives the roots enough room to grow. These germination plugs are perfect when coupled with 1020 bottom trays.
- Liquid Fertilizer. You’ll need to feed your plants from the seedling stage, all the way to fruiting. This organic fish & seaweed blend is a very versatile option. Use it half-strength for young plants and full-strength for established plants.
Browse our list of tools, fertilizers & pesticides, indoor growing products and seed shop recommendations – we hope you find our selection useful and it saves you some time!