Most growers know about the benefits of LED grow lights. But making the switch can be expensive: even cheap LED grow lights have a higher initial cost than other types of grow lights.
Fortunately, you'll make up that cost over time, because LED lights last longer than conventional grow lights.

Despite being new to horticulture, LED grow lights have proven to be better than all of the available sunlight substitutes. Now, what actually makes them better?

Although the type of crops and the economics matter, there are still many reasons why LED grow lights prove themselves to be better than other ordinary LED lights.

Some of them are mentioned below:
Energy-Saving: They are highly efficient in terms of saving energy. They produce the same amount of light, but their energy consumption is less than the others.

Ideal Alternative to Sunlight: They act just like sunlight for the crops, as they have a broad range of wavelengths that are needed to grow healthier crops with higher yields. 

Cost-Effective and Reliable: They only require a one-time, high-cost investment, but they save you a lot of money in terms of less and affordable power bills in the long run. They are also very durable.

Less Heat Production: LED grow lights produce significantly less heat than traditional LED lights. The main advantage is that it eliminates the need to install exhausting and cooling systems and ventilation fans.

Non-Contaminating: Even after the LEDs have been removed, you will not have to worry about any kind of contamination, because they leave no traces of chemical contaminants behind in the soil or air.

Long-Lasting: The LED grow lights last longer than other lights. LEDs last for about 50,000 or more hours. While, on the other hand, any other bulb would not last more than 10,000 hours, which is a huge difference.

Non-Damaging: Since LED grow lights emit a meagre amount of heat, you can install them closer to the plants without the fear of causing any damage to them.

ECO Farm MB3 Pro 760W LM301B LED Grow Light

Features:
High efficiency + high yield ECO Farm LED grow light is equipped with tWith 2880 pcs SAMSUNG LM301B diodes+80 Osram 660nm, with high PAR/PPF efficiency up to 2.8 umol/J and powerful output, enabling you to Obtain higher output. Only consumes 760W. The ultra-thin and unique 180° foldable design grow light is easy to stretch or fold. It is very suitable for large-area planting and commercial planting. The perfect coverage area is 4*6 feet. Both sides can be folded freely from 0° to 180°, easy to install, save space, and easy to carry, no need to worry about hurting hands and lights. The dimming knob is ideal for growers to adjust the light intensity according to different growing stages., which provides the needs of each stage of the plant, allows the plant to obtain the perfect growth effect flexibly, increase the yield, and save energy costs at the same time.

Model: MB PRO 760W
LED: 2880 301B + 80 Osram 660nm
PPF: 1960–2128μmol/s
Wattage: V1 spectrum:700W / F1 spectrum:760W
Weight: 30.73lbs/13.94kg
Light Source： White Chip& red chip
Efficacy： 2.6~2.8 μmol/J
AC Input Voltage： 120–277V AC,347–480V AC,50/60Hz
Thermal Management： Passive Cooling
Material： Aluminum
Fixture Dimension： 1199mm*1158mm / 47.2"*45.6"
Max.Ambient Temperature： 95°F / 35°C
Dimming： 0–10V Dimmable
Mounting Height： ≥ 6" (15.2cm) Above Canopy
Out Packing： 127*20*66.5cm
Packing Weight： 17.8kg

Enlite Ceres 780W Full-cycle LED Grow Light

Features:
Thsi Enlite LED grow light with unique designed extended 6 bars LED grow light provide more even and full canopy coverage, especially to the outer edges cultivation areas. The Led grow lights draw 780 watts with 2045 umol/s, achieving an impressive PPE, coverage for 4'x4' of high-yielding full-cycle growth. Full spectrum is perfect for veg to bloom, to adapt to each phase of the plant cycle. The LED grow light design and aluminium heat sink on the back contribute to better airflow and great heat dissipation. The grow light comes with a detachable driver and long power cord, there by reducing ambient heat in your growing space for extended lifespan. With the waterproof coating on the LED diodes, worry free of the moist environment.

Wattage draw: 780 watts
HID replacement: 1000W DE
LEDs: Samsung and Osram
Beam angle: 120°
Lifetime: >50,000 hours
Spectrum: Full-spectrum white
Dimming: 0–10v
Efficacy: 2.6 umol/j
Total Photon Flux: 1,976 μmol/s
BTU's: 2,660
Coverage Area: 4'x4' to 5'x'5
Hang Height: 6"-12" above canopy
Dimensions: 44" L x 44" W x 2" H
Weight: 35.5 lbs
Voltage / Amperage: 6.5A @ 120V, 3.3A @ 240V
Certifications: CE, RoHS, ETL certified
Waterproof/dustproof: IP66
Manufacturer's warranty: 5-year warranty

How Many Plants Can I Grow?

In general, each cannabis plant you grow requires at least 1sq ft of space.

After germination, I like to place one plant in a large 5-gallon fabric container, which has a diameter of roughly 1 sq foot.

My plant will stay in this pot until it flowers.

This allows the plant to grow big and strong without other plants or tent walls obstructing its progress. I also don't like transferring plants too often, as it puts a lot of stress on the plant.

So this as a guideline, I would be able to grow between 1–6 plants in my example above.

Make Sure Your Canopy Is Covered

Now, it's also important to understand that most LED grow lights will usually only be able to cover around 1- 6 plants.
If you want to grow any more plans than this, you would need to purchase multiple lights to hang side by side ( called daisy-chaining ) to cover the canopy and ensure each plant is getting equal light.

The table below shows how the number of watts you require increases with the size of your grow space. I've also included how many plants each size of grow light will be adequate for.

Note: 1 sq ft grow space = 50 watts LED grow light
* The size of the grow space in these situations will require you to purchase multiple lights to hang side by side to ensure the entire canopy is receiving light.

Note: The values above are for flowering. During the vegetation stage, you will require around half the power ( 25w ) the best quality LED grow lights come with "Veg and Bloom switch" that optimize the intensity of the light for the vegetation and flowering stages.

How To Measure LED grow Light for Cannabis Plants
LED grow lights come with different heat intensities and brightness levels depending on the wavelength and wattage.
Plants absorb the light that helps with their growth process. Any extra heat from the lights causes damage to the plants' foliage and the growers considering how much they put into the process.

The most basic way to measure the intensity of the LED grow light is by using the hands. If the heat is not bearable, enough for your skin, then it could also mean that it will be unbearable to the plants. If the dorsal side of your hand feels comfortable under the lights, it means that your plant canopies will feel comfortable too.

Besides the hand method, you can use the PAR and PPFD methods to measure the light intensity. Many cannabis growers do not know how to measure grow light for their plants irrespective of the lighting systems using the par and PPFD methods. The first step would be to understand the definitions of PAR (Photosynthetically Active Radiation and PPFD (Photosynthetic Photon Flux Density)

PAR is the light that cannabis plants or any other type of plants see. PAR is also the light plants use for photosynthesis with ranges from 380 nm to 780 nm.

PPFD, on the other hand, is the total light density received by the plant throughout the growth process. PPFD measurements are in micromoles per square meter, per second, and it provides growers with the ability to get accurate measures for photosynthesis light intensity at their canopy levels. Another benefit of knowing about the PPFD is to avoid placing the lights too close to the canopies, thus preventing discolouration, stunted growth, burning, and bleaching.

Conclusion

Hopefully, this article has been able to shed some light ( pun intended ) on how to pick the correct size to grow light for your project.

As long as you know the size of your grow space and how many watts per square meter you need, choosing an LED grow light is pretty simple.

Good luck with your growth!