Technology has come a long way in the past decade, and with it, we have seen the rise of LED grow lights in the indoor marijuana growing industry. Using LED grow lights instead of traditional grow lights is not only better for your plants, but it is also efficient and will save you a ton of money.

Why plants need light when they grow?

At first, we should know what plants need when they grow. There are four main elements for the growth of plants: air, water, nutrition, and light. Nutrition provides essential chemical materials for plants. Air contains CO2 and H2O which are necessary during photosynthesis and they can be transformed into oxygen and glucose. Light works as a catalyst that motivates this process.

What's the role of the sun in the growth of plants?

As is known to all, the sun is the main source of light in nature. So it plays an important role in the growth of plants.

Sunlight is broken down into 3 main components due to their varying wavelengths. Natural sunlight contains 50% visible light, 43% infrared light and 7% ultraviolet.
Each one of these components has a different function in the growth of a plant. Visible light is made up of various colors on the light spectrum that vary across a wavelength range between 380 nm to 750 nm. For photosynthesis plants use a wavelength between 400 & 700 nanometers. Thus making visible light produced by the sun ideal for plants in order to help them photosynthesize. 
The second biggest component of sunlight is infrared light. Infrared light sits right on the edge of the visible light spectrum at 700 nanometers. It provides heat and has been found to play a part in the blooming of flowers. Especially indoor grows using fluorescent lights without infrared. Plants have been found to not bloom until there is a suitable amount of infrared light available. Finally, ultraviolet light. One of the shortest wavelengths produced by the sun varying from 10–400 nanometers. 

As far as UV light is concerned with plant growth, it provides many benefits. Previously it was seen as a bad thing by lighting manufacturers and was also attempted to be removed from their lights. However, today is a different story. UV is well proven to ignite plants to create defense proteins which lead to better colors, tastes, smells and resistance to diseases. Overall making healthier stronger plants. UV also speeds up the germination process of seeds.

Light spectrum warning
Although all three of these lighting spectrums each play a specific part in helping a plant grow and develop into something beautiful. They come with a warning and should be used appropriately. Too much of any of these three light compositions will result in an unhealthy plant! So be careful!

ECO Farm 650W Samsung LM301B Full Spectrum Detachable LED Grow Ligh...

Features:
The ECO Farm grow light uses 1632 Samsung LM301b with 288 OSRAM LEDs to ensure high-efficiency PPE 2.8umol/J, better heat dissipation, and long service life. The PPF output of this plant light is 1820umol/s. This 660W lamp can obviously replace 1000W HPS. 6 LED growth lights, each rod is covered with high-grade glue, waterproof, and easy to clean, not easy to be filled with dust. This plant growth light also uses a special dimmer, which can precisely adjust the brightness. 0–10 levels are optional. This means that you can see clear brightness levels and record while adjusting. No need to worry about differences. It also has Samsung lm301b 3500k +Osram 660nm Red, close to natural sunlight, suitable for vegetable blooming and indoors,. Finally, It is a fanless and zero-noise design, which is very quiet. Compared with the quantum board LED plant growth lamp, it dissipates heat faster and has a lower surface temperature-no need to worry about burning your plants, and the lamp has a longer life. Ideal for growing tents of 5x5 feet. If there is no tent, it is recommended to cover a 6x6 foot seedling growth area and a 5x5 foot best flowering area.
Input Voltage：AC 100–277v (347–480V customized)
Actual Power：650W/6 bars
Power Factor：>0.9
Dimming Range：0–10V/1–10V
Light Distribution：120 degree
Spectrum：3500K+660nm
LED Brand：Samsung lm301b+OSRAM 
Number of chips：632pcs LM301b 3500K +288PCS OSRAM LEDs 660nm
PPF：1820umol/s
Efficacy：2.8umol/J
Fixture Dimensions：47*43.4*1.9inch (1194*1104*50mm)
Fixture Weight：16KG
Warranty：5 years
Lifespan：>50,000 hours
CRI：>80
Certificate：ETL&cETL, DLC, CE, RoHS

PRO TECH 645W LED Grow Light

Features:
Pro-Tech Lighting is committed to producing the most reliable and performance LED plant growth lights on the market for wholesale, indoor planting, and large-scale gardening projects. The foldable and powerful Pro Tech 6450W LED is a linear multi-strip fixture that can produce a high PPF of 1200 µmol/s and a photon efficiency (fixture efficiency) of 2.8 µmol/J. The 645w Pro-Tech LED plant growth light is manufactured with top-notch components, including high-quality Pro-Tech drivers and high-quality LEDs from Samsung and Osram. For different cultivars, breeding, and vegetative growth periods, the light can be dimmed without loss of efficiency. The high-efficiency and low-power LED configuration with LED bars reduce the temperature of the LEDs, thereby increasing output and improving light maintenance.
Efficiency: 2.8 µmol/J
PPF: 1800 µmol/s
Input Voltage: 200–240V, 50–60Hz
Power Consumption: 645W
Footprint: 1.5×1.5m
Waterproof: IP65
Lifetime: 60 000 hrs
Light Distribution: 120°
Light Source: Samsung Diodes
Dimmable: OFF-25%-50%-75%-100% with 0–10V Light Dimmer (Included)
External Control: External Controller
Weight: 11 Kg
Dimensions: 127cm x 110cm x 8cm
Spectrum: Full Spectrum +
Mounting Height: 6″ Above Canopy

Choosing the right size light for the best coverage and a healthy garden

Lumen ratings measure brightness for human eyes, so they aren't very helpful for selecting grow lights. Wattage is a measurement of power, but this isn't helpful either, except for judging how much electricity the light will use. Instead, look at specifications on PAR and the manufacturer's guidelines on square foot coverage.

PAR
PAR means photosynthetically active radiation. It's a measurement of the light's intensity and what colors it emits. PAR measures light emitted in the 400nm to 700nm spectrum, or from blue light into infrared. The higher the PAR number, the more useful the light is for growing plants.

Coverage
Most manufacturers will state information like the area their light covers at certain heights above the canopy of the plant. For example, one might say their lamp illuminates 4 feet by 4 feet at a height of 18 inches. When you're germinating seeds, you may hang a bright light up higher than this, and therefore you'll have a larger coverage area.

But when you're trying to get tomatoes as big and juicy as possible, you'll want to lower the light closer, which will shrink the area it covers.

Other factors to note
One LED grow light may not be large enough to cover all the plants you want to grow. You might need two or more. Take into account the shape of the light. Remember that the light will need to be powerful enough to penetrate foliage in a few weeks. It's better to buy a more powerful light than you think you'll need.

LED plant grow light use precautions 

Now that we have a full spectrum LED grow light, what should we do next to take care of our plants?
1. Regular switch plant grow lights. For example, if plants can get enough sunlight from 9 am to 5 pm, daylight can already meet their needs for growth. So we can turn on the grow light from 7 am to 9 am and from 5 pm to about 9 pm. In winter, the sun shines shorter, so we can supplement the light for a longer period.

2. Set a reasonable distance of lighting. Being too far from the plant, the light is not enough and it cannot achieve the best effect. Being too close to the plant, the light is not complete and it will cause the plant to receive uneven light. As a result, the plant growth situation can't reach your expectations. Different LED plant grow lights have different illumination distances, which need to be adjusted according to the product manual.

3. Pay attention to the maintenance of plant grow lights. When you buy a plant grow light, please follow the instructions provided by the merchants to install, check and maintain them. If you don't clean them at all or you clean them in an incorrect way, the damage to the light will be large.

Conclusion
You don't have to go for a premade LED light. If you're tech-savvy, you could build your own LED kit. There are many guides and tutorials on the web, which will show you how to build a potent LED light that will be quite a bit cheaper than the premium premade LED lights, but will provide close to the same quality of light. Just prepare and take your time to do all of your homework in case you go this route.