LEaD the Way – LED lighting takes us forward

As grow-lighting technology forges relentlessly onward, it’s impossible to make an honest claim to be leading the way. Even the scientists and engineers at the sharp end of LED lighting development tend to be narrowly focussed on a single product type at any one time. They can only be leaders in their own arena. It is maybe more realistic to accept that LED technology itself is leading the way, drawing us onward to a future of immense potential.

When it first became possible to use LED lighting for growing plants, the equipment available was expensive, and tended to be aimed at a target market of large commercial growers or relatively wealthy, technology-enthusiast growers. Early LED grow lighting had its problems too, with over-emphasis on the blue and red light resulting in a purplish light output with insufficient mid-spectrum wavelengths. While it is still possible to find highly priced, specialised LED lighting products, increasingly the LED horticultural lighting market is becoming dominated by products with broader appeal and more reasonable prices. Most growers prefer to find LED equivalents to the HID and fluorescent lighting that they’re accustomed to using. It’s natural that we don’t want to alter our familiar growing methods, we just want to find the best light for the job.

The fast-developing LED grow light market is now most active in substitution, as people renewing their lighting kit consider options which might save on energy or offer fresh advantages. Growers who have up to now used dual-spec HPS Lamps may be tempted to swap them for full-spectrum LED bar fixtures, which will do the same job with less heat output, lower energy use, and a more even spread of light. People who propagated under bulky, fragile cool CFL lamps might nowadays use a lighter, more robust LED bar grow-light, or a plate-format LED with a spectrum including enhanced blues.

Full spectrum plate LEDs may appeal to growers with smaller tents or might be used as supplementary lighting by bigger growers. And of course, TLED grow lights are an obvious replacement for T5 fluorescent tube lights.
But there are also LED lights available now which can make successful growing easier than it has been. For example, with HID lighting, it can be advantageous to tune the light spectrum to the plant’s life cycle. A grower might opt for a metal halide lamp during the vegetative (growth) stage of his crop, benefitting from the increased UV and blue light in its spectrum. At (or just before) the flowering stage he would switch to an HPS lamp to make use of greater light intensity for flowering and fruiting. Full-spectrum LED lighting fixtures now on the market have a higher light output and better efficiency than HID lights and emit PAR wavelengths and intensities of light suited to any stage of the plant life cycle, removing the need to switch from one lamp to another.

Note: PAR – Photosynthetically Active Radiation. This is the range of wavelengths of the electromagnetic spectrum between 400 nm and 700 nm which is used by plants for photosynthesis. It corresponds approximately with the wavelength range of visible light.

Supplementary LED lighting is also becoming available which is very simple to use, and which can add UV and far-red wavelengths of light to either full PAR spectrum LED lighting or to non-LED lighting set-ups. Such lighting must be applied sparingly, for reasons described below. These supplementary lights are usually powered and controlled independently of the main full-spectrum lighting and timed to light for no more than a couple of hours each day, often near the end of the photoperiod. However, they are easy to set up, and purchase and running costs are very low.
The grower must exercise caution – too much UV light can be harmful to plants, and too much far-red light can produce unwanted effects.

Natural sunlight contains three kinds of UV light;
UVA (wavelengths 315 nm – 400nm)
UVB (wavelengths 280 nm – 315 nm)
UVC (wavelengths < 280 nm)

Most UVC light emitted by the Sun does not reach the Earth’s surface, because it is filtered out by the Ozone in the atmosphere. This relatively short-wavelength light has more energy than UVB and UVA and the greatest potential to do damage to both animal and plant life on earth.

UVB light can also be damaging to plants, as it can disrupt the bonds between atoms. Only around 10% of UVB light emitted by the sun penetrates the ozone layer to reach the Earth’s surface. UVB also cannot pass through glass. UVB is both beneficial and potentially harmful to animal life – it stimulates production of Vitamin D, but too much exposure can lead to skin cancer.

UVA light is the least damaging form of UV light for plants, and around 50% of the UVA emitted by the Sun reaches the Earth’s surface.
Grow lights don’t emit significant amounts of UVC light because it has no beneficial effect upon plants. However, there are UVC light-wands available, intended for use as grow-room sanitising tools which kill off microorganisms. With sufficient exposure, UVC light can extinguish any form of life.

UVA and UVB light are known to be beneficial to plants if exposure is limited. While over-exposure can cause harm, short periods of exposure at moderate levels encourage the plant to synthesise its own protection against UV, in the form of terpenes (essential oils) and flavonoids (pigments). These protective substances in turn improve the flavour and colour of the crop.

Far-red is light from a band of the spectrum ranging from the longer wavelengths of visible red light into the shorter wavelengths of infrared.
Plants use pigments called phytochromes to sense the proportion of red light to far-red light that they receive. Phytochromes perform various functions within the plant, including genetic controls, germination and seedling development, chlorophyll synthesis, shade avoidance and adjustment to varying light levels, and photoperiodism (the flowering response).

There are 2 kinds of phytochromes, P_r and P_fr, which convert back and forth from one kind to the other dependent upon the light received by the plant:
P_r – responds to red light by converting to P_fr
P_fr – responds to far-red light by converting to P_r
When plants receive far-red light, the ratio of P_r to P_fr in the plant becomes higher, and vice versa. Plants with an increased ratio of P_r to P_fr tend to react as if they are not receiving a full day’s complement of light. The implications of this depend upon the stage the plant is at in its life cycle:
Seeds need sunlight to germinate and grow. If exposed to too much far-red light, seeds might not germinate, and growth will be stunted.

In the vegetative (growth) stage, too much far red will stimulate the plant to seek more sunlight. It will grow tall, thin, and leggy, with enlarged leaves. The plant will be weakened.
At the flowering stage, extra far-red light received increases the ratio of P_r to P_fr within the plant. The plant reacts as if the day is shortened, and the night is longer. If the plant is a short-day (late summer) flowerer, this increase will stimulate flowering. For long-day (spring) flowering plants, the effect is reversed – less far-red light will stimulate flowering.

If a grower has supplied all the other requirements of his plants and then carefully tunes his photoperiod (lit hours) and adds supplementary LEDs for UV and far-red, it is possible to stimulate them to flower a little earlier, and to harvest a better-quality crop. Faster, better crops can go a long way toward paying for those LED lights.
LED Grow Lighting products coming soon from Hydrogarden include:
LUMii BLACK Blade 100w LED 03-155-950


A compact, cool-running and efficient plate-format LED alternative to T5 lights, CFL lamps or 250 W Metal Halide lamps. Giving full spectrum white light with enhanced blues, it is ideal for vegetative growth and propagation. The fixture can fully light a large propagation tray and is small enough to be used in a LightHouse Clone Tent. Powered directly by mains electricity via the 2 m power lead supplied. Complete with hanging slings for easy installation.

LUMii BLACK Blade 200w LED 03-155-955


A compact, cool-running and efficient plate-format LED alternative to 250 W and 400 W HID and 315 W CMH lamps. Its full, balanced spectrum white light with supplemented red is ideal for the entire plant lifecycle. Large enough to light a growing area up to 1 m², it can also be used as auxiliary lighting in a larger grow room. Dimmable using integral control and can be scheduled using a plug-in timer. Powered directly by mains electricity. Complete with hanging slings for easy installation.
LUMii BLACK Blade 400w LED 03-155-960


A cool-running and efficient plate-format LED alternative to 600 W HID lamps. Its full, spectrum white light with supplemented red is ideal for the entire plant lifecycle. The 2-plate, adjustable design allows the fixture to be used to light a 90 cm x 90 cm tent or a larger tent up to 1.2 m², with plates set to give the optimum light spread. There is provision for mounting a LUMii Black Bar 30w UV/FR LED between the adjustable plates to provide additional UV and Far-Red light if required. Dimmable, and can be scheduled using a plug-in timer. Powered directly by mains electricity. Complete with hanging slings for easy installation.

LUMii BLACK Bar 30w UV/FR LED 03-155- 990


A bar-format LED light providing supplementary UV and Far-Red light to extend the spectrum of light emitted by other light sources. Designed to be attached to the LUMii Black Blade 400w LED fixture, it can also be used alongside any other full spectrum grow light to increase the yield and quality of crops, stimulate growth and promote flowering. Plug and play with its own power lead, it can be controlled via a timer.

PowerPlant Tube 25w UV/FR LED - Pack of 2 03-155-100


Tube-format supplementary lights which add UVA and Far-Red to your grow light spectrum. A pair of Tube LEDs can be added to most multi-bar LED Fixtures (using brackets provided) to increase the yield and quality of crops, stimulate growth and promote flowering. They may also be hung alongside any other type of full spectrum grow lighting. Both Tubes, when linked, are powered from one mains power socket and can be scheduled by a timer. An array of up to 36 linked tubes can be powered from one 13 A power socket.
EnviroGro by LUMii 120cm (4ft) 4 Lamp TLED Fixture 03-155-415
A versatile light unit with four 18W TLED lamps, switchable to use either 2 inner, 2 outer or all 4 lamps. The unit can be mounted to suit your application. The cool running TLED lamps will not heat your growing environment. Multiple units can be linked and powered from a single outlet socket. Highly energy efficient with a long working life expectancy.
LED Grow Lighting products already available from Hydrogarden include:

ROOT!T 26w LED Grow Light 03-155-900


Ideal for propagation, with a colour temperature of 6500K, it can also be used for the vegetative (growth) stage of the lifecycle of small plants. Its light spread will cover most standard-sized propagation trays. Length 50 cm. Universal hanging hooks are provided. It has an integral power lead and can be controlled via a timer.

ROOT!T 42w LED Grow Light 03-155-910


Ideal for propagation, with a colour temperature of 6500K, it can also be used for the vegetative (growth) stage of the lifecycle of small plants. Its light spread will cover two standard-sized propagation trays. Length 96 cm. Universal hanging hooks are provided. It has an integral power lead and can be controlled via a timer.

EnviroGro by LUMii 60cm (2ft) 2 Lamp TLED Fixture 03-155-405


A versatile light unit with two switchable 9W TLED lamps. The unit can be mounted to suit your application. The cool running TLED lamps will not heat your growing environment. Multiple units can be linked and powered from a single outlet socket. Highly energy efficient with a long working life expectancy.

EnviroGro by LUMii 60cm (2ft) 4 Lamp TLED Fixture 03-155-410


A versatile light unit with four 9W TLED lamps, switchable to use either 2 inner, 2 outer or all 4 lamps. The unit can be mounted to suit your application. The cool running TLED lamps will not heat your growing environment. Multiple units can be linked and powered from a single outlet socket. Highly energy efficient with a long working life expectancy.

PowerPlant 650w LED Fixture 03-155-090


A high-performance, high-quality 8-bar LED fixture with internal drivers. Compact, lightweight and easy to install, simply unfold and hang, it makes no compromise on efficacy and output. Its open construction and low heat output assist airflow and heat management. Producing full spectrum light from Osram and Samsung LED chips that is ideal for both growth and bloom. Perfectly suited for use either as a single standalone fixture or as part of an array of up to 100 fixtures controlled by the PowerPlant LED Controller. Overall size 120 cm x 110 cm, ideal for a 1.5 m x 1.5 m tent.

PowerPlant 400w LED Fixture 03-155-085


A high-performance, high-quality 4-bar LED fixture with internal drivers. Compact, lightweight and easy to install, simply unfold and hang, it makes no compromise on efficacy and output. Its open construction and low heat output assist airflow and heat management. Producing full spectrum light from Osram and Samsung LED chips that is ideal for both growth and bloom. Perfectly suited for use either as a single standalone fixture or as part of an array of up to 100 fixtures controlled by the PowerPlant LED Controller. Overall size 90 cm x 90 cm, ideal for a 1.2 m x 1.2 m tent.
PowerPlant LED Controller 03-155-095


Designed to control  PowerPlant LED Fixtures but also compatible with PowerPlant Controllable Ballasts, The PowerPlant LED Controller is dual-channel and can schedule and control 2 independent arrays of up to 100 LED Fixtures per channel (200 Fixtures in total). Each array has its own 5 m remote temperature sensor. Programmable to your preferred day/night cycle and dim setting with Sunrise & Sunset function to protect plants from shock. Temperature responsive auto-dim and emergency shutdown. 
LUMii BLACK LED 720w 6 Bar Fixture 03-155-130
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A high-performing, high-efficiency mid-range 6-bar LED fixture, output PPF 1870 µmol/s. Full spectrum plus 660 nm diodes, suitable for entire plant life cycle. Lightweight and easy to install, it is powered by a LUMii BLACK 600W Electronic Ballast (not included) which can be either mounted on the fixture or positioned remotely. Overall size 110 cm x 108 cm, ideal for a 1.5 m x 1.5 m tent. Available as solo Fixture or Fixture and Ballast bundle