10 factors to help you choose the best LED Grow Light

10 factors to help you choose the best LED Grow Light for your Grow System

Regardless of the scale of your LED Grow Operation it is essentially the same process in deciding what the best LED Grow Lights to invest in are. Here we present ten essential factors when growers are looking for an ideal LED Grow Light:

1.What is the grow area within which I would like to install Grow Lights?

2.What is the ideal wattage per square meter (W.m-2) for my Indoor Grow System?

3.Is Light Uniformity Important When Purchasing an LED Grow Light

4.What is the LED Grow Light with the best efficacy (µmol.J-1)

5.What is the ideal light spectra (light quality) for my Grow System?

6.The colour of the LED Grow Light matter?

7.How will the LED Grow Light Fixture affect my electrical bills?

8.Should the overall quality of the LED Grow Lights built-in components be considered?

9.What is the ratio being used to evaluate the cost benefit of an LED Grow Light? €/wattage or €/µmol?

10.How should LED Grow Light Modularity and Warranty Influence your Final Choice?

1. What is the grow area within which I would like to install Grow Lights? 

This is the most critical point that growers should pay attention to. Often growers ask which is the best LED Grow Light? Our usual answer is it depends for how much Grow Area you would like to install Horticulture Lighting within.

The defined grow area should have it’s effectiveness maximised by selecting an LED Grow Light according to its technical dimensions. Or it may produce too many or too few photons for the desired plant species.

What’s the best distance between LED Grow fixtures and plants? The answer isn’t simple, there are a number of factors involved such as: stage of the plant, plant species, desired light intensity, etc.

First the grower should define their Grow Indoor/Outdoor System dimensions, then properly choose an LED Grow Fixture with the appropriate dimensions, and an ideal light source output according to the light necessities of the plant species.

Use the Photontek Led Grow Light Calculator and you will be able to find the best Photontek fixtures for your grow!

2. What is the ideal wattage per square meter (W.m-2) for my Indoor Grow System?

Typically, hungry plant species such as Tomatoes or Cannabis need high level daily light index doses, commonly called DLI.

Cannabis species require 30-45 moles per day depending on the growing stage, which can be pushed to 55 moles per day when supplementing the controlled grow environment with carbon dioxide (CO2).

It is crucial to select an LED grow light which can produce enough PPFD to fulfil the optimal DLI required. Which means in terms of wattage per square meter about 300-400 watts needed to be applied in the grow area.

As the future of LED Grow Lights turns to increased efficiency by converting electricity into usable photons for plants, the wattage per square meter value tends to be reduced as the efficiency of LED chips are improved or other technology integrated.

3. Is Light Uniformity Important When Purchasing an LED Grow Light

When purchasing LED Grow Lights, it is important to consider and ensure that all of the produced photons are uniformly spread throughout the entire cannabis canopy.

LED Grow Lights when developed for a horticulture indoor space, generally have a steady spread of produced photons throughout the canopy area.

A good light spread, technically means that a minimum of 50% (Minimum PPFD / Average PPFD x 100) of light uniformity is considered.

For example, a PPFD of 1000 µmol.m-2.s-1 in a cannabis horticulture indoor system represents a minimum of 500 µmol.m-2.s-1, usually located at the edges of a cannabis grow area.

The uniformity translates to how the light is spread over a canopy. It has an important role when growers are selecting LED Grow Lights and to ensure that all growing phases are covered in a single grow area. Also it avoids uneven canopies and differences in irrigation and nutrients ratios. It will promote a uniform photosynthesis ratio for the entire canopy.

PAR maps on LED fixture spec sheets show PPFD measurements taken at specific distances from the LED fixture. They can be used to understand the coverage area and light spread from a single LED grow light.

Figure 2: XT 1000W CO2 PRO LED @ 100% power from 40 inches distance from top 5´x5´canopy.

4. What is the LED Grow Light with the best efficacy (µmol.J-1)

The efficacy of an LED Grow Light technically measures the conversion of electricity into usable photons that fall in the PAR (Photosynthetically Active Radiation) region.

This is a pertinent matter. This specification can be calculated by a grower if not provided by the manufacturer, by simply dividing the total PPF (Photosynthetic Photon Flux) output of the LED Grow Light by the total input power to get the PPE (Photosynthetic Photon Efficacy).

Some LED Grow Lights may have 1000 Watts but with a low efficacy. For example, a 1000W LED grow light with 2.3 µmol/J efficacy will produce 2300 µmol.m-2.s-1 PPF whilst a 1000W LED 2.9 µmol/J will produce 2900 µmol.m-2.s-1 PPF.

More useable LED grow light output from the same power consumption covering the same grow indoor area.

5. What is the ideal light spectra (light quality) for my Grow System?

This is another critical feature to look at. Fortunately, there’s a spectrum graph with all the colours available which represents the number of produced photons with different wavelength of energies.

For example, if the grower wants to grow Cannabis in an indoor grow system, from seedling to harvest, he should choose a full spectrum horticulture LED fixture.

An indoor LED Grow Light spectra produces approx. 20% blue spectrum which comes from the white diodes, ideal for the vegetive stage, and around 38% of it is red, having a greater impact in the flowering stage.

Outdoor cannabis growing spectra is a different story. The spectra produced by a supplemental LED light source should have specific blue and red spectra.

Ideally, the blue and red ratios should be selected according to which cannabis plant grow stage the crop is in, this also applies to other major plant species.

Then, adjustments should be made with the artificial LED light quantity, this should be adjusted in relation to the average natural light available in the grower’s specific greenhouse location.

6. Does the colour of the LED Grow Light matter?

Usually defined by CRI (Coloured Rendering Index), this is the parameter that represents accurately how the light produced from an LED grow fixture will aid or obscure your ability you to view the plant with your eyes and see the colour of the plant with the most accuracy.

There are LED grow lights that illuminate your canopy with purple coloured light which will decrease the likelihood of detecting disorders in your plants. The higher the CRI the closer a crop will look to its natural colour. Grower’s don´t want to work in a purple lit space.

Bigger CRI values indicate more white light from the fixture.

7. How will the LED Grow Light Fixture affect my electrical bills?

Thirty years ago, growers just focused on watts. The higher the value the better. Watts is a measurement of energy consumption.

If you considered a single 1000 W Led grow light fixture, it means 1 kW of energy consumption per hour. With this you can predict your future electricity bill.

If you are looking to profit from your plants, you should do the maths to see if the profit covers these expenses.

In the end, when choosing an LED grow light, cost of energy consumption must be considered in relation to project economic viability.

The sum of the total of LED grow fixture input power in watts (W) will give the energy consumption in kW/h. For example, running 10 x LED fixtures drawing 650W of input power each is calculated as 6.5 kW/h at your energy provider’s price rate.

8. Should the overall quality of the LED Grow Lights built-in components be considered?

Quality of the design, build and materials used are important for high performance & long-lasting durability.

The chassis must be robust and solid. Highly efficient aluminium heat sinks allow for passive cooling instead of expensive and noisy fans.

9. What is the ratio being used to evaluate the cost benefit of an LED Grow Light? €/W or €/µmol?

There’s price per watt and price per micro mol. We should not focus only on the price per watt because this is purely related to the wattage. €/Wattage can lead to error in judgement when looking for an LED.

€/micro mole is more effective. Having a fixture with a higher efficacy focus is better because plants respond to micro moles and not watts. Growers must focus on plant needs and PPF output cost.

10. How should LED Grow Light Modularity and Warranty Influence your Final Choice?

Replaceable parts, modularity of design, horticulture light company assistance and maintenance, should be factors carefully considered. This can help you decide where to buy.

The ability to change a driver, an LED bar or even a PCB helps to create more trust in the products longevity. It also makes it easier to re-sell your used equipment. It is more efficient to replace/upgrade individual components, light bars or drivers than replace entire fixtures.

For example, our intelligent LED drivers can automatically adjust the amount of power in scale to the number of light bars connected to the fixture allowing more flexibility in system setup and use.

Warranty, another big deal. Make sure you have a complete and long warranty and that the company stands behind.

FAQS – Quick questions and answers about choosing the best LED Grow Light for your Grow System

Q. What is the first factor of choice to consider when buying an LED Grow Light?

A. Grow area. First define your grow space. After that, a choice of an LED Grow Light will depend on how it can effectively cover the desired grow space.

Q. What is the best LED Grow Light Spectrum to grow indoors?

A. Generally speaking full-Spectrum LED Grow Lights are the best for plant growth. Spikes in the blue and red regions and a good portion of green will have a positive impact on how plants will develop.

Q. Are LED diodes brands also a feature to consider?

A. Yes. The most well know and reliable are Lumileds (Philips), OSRAM and Samsung. Whether the LED Grow Light manufacturer can guarantee a light decay of L90 > 50000 hours (10% of light decay after 50000 hours of and LED fixture continuously working), should be a deciding factor.