When it comes to the lighting requirements for different plants and growing environments, light spectrum is of paramount importance. The grow light spectrum required for profitable plant yields will depend on the environments in which the lights are being used, the type of lights being used, and the plants themselves. To fully benefit from the potential and capabilities of a well-designed LED grow light set-up, you need to understand exactly what LED grow light spectrum is required and how to customise this for your environment.
The lighting requirements for the following grow environments – field, glasshouse, vertical farm, underground bunker, rooftop city garden, or polytunnel – will depend on the environmental requirements that the crop requires. As John Matcham, Technical Director at Light Science Technologies points out, “Breaking down the essentials is important to really understanding what the crop needs from its environment and the best possible LED grow lighting layout.”
The Grow Light Spectrum in Natural Light Conditions
“The first step is to separate those grow environments with natural light and those with 100% artificial light,” adds Matcham. “Those defined as natural light are those spaces where natural sunlight is used in conjunction with artificial light, either to extend the day length or to increase light intensity, or both.”
The field:
Football, rugby, cricket and baseball pitches often use additional light to enhance the growth of their grass. This is particularly of value in areas that experience hard wear and tear and that need quick growth. The blend of artificial light with natural light can improve the speed at which the grass grows which makes it a lot easier for the owners to manage turf and training. Every location has its own issues and the orientation of a stadium relative to the sun will present different shadowing patterns. A suitable program of lighting will compensate for this.
The glasshouse:
Often used in the production of peppers, cucumbers, and tomatoes, glasshouses use additional lighting to enhance production of food crops. This use of LED grow lights encourages plant growth throughout the canopy of vines, not just within it. By placing the LED grow lights within the crop and not just above it, you can achieve remarkable results.
Polytunnels and rooftop gardens:
Just as with the glasshouse and the field, these grow spaces benefit from a combination of natural and artificial light to increase production performance all year round. LED grow lights can be used to enhance summer, or to ensure growth in winter where the days are shorter.
Managing the LED grow light spectrum in environments that blend natural and artificial light for optimal results will depend on the target crop and your overall requirements. Natural light changes with the seasons, days get longer or shorter, and the quality of the light changes along with its colour/wavelength. Plant species have evolved to synchronise their lifecycles to suit these changing environmental factors and so your LED grow light spectrum will need to take these into account.
You need to consider light, CO2, temperature, humidity, and air movement as well as soil temperature, water, nutrients and O2. The grow light spectrum in this environment will be in balance all these factors, along with the different spectrum elements below, to create the perfect grow balance.
The Grow Light Spectrum in Artificial Light Conditions
In areas where the light is 100% artificial such as a vertical farm, underground bunker or tunnel and some types of poly-tunnel, LED grow lights can be used to emulate the different light conditions that plants require. For example, some polytunnels are not transparent and keep out natural light so they can produce crops like mushrooms.
“In these polytunnels we still need light to see so LED grow lights provide an efficient solution that doesn’t generate too much heat,” explains Matcham. “Some light can be used to emulate night conditions that will help with the production and reproduction of mushrooms.”
As with natural light growing spaces, the environmental factors that influence your choice of LED grow light spectrum are the same. You will need to factor in light, CO2, temperature, humidity, air movement, soil nutrients, water, and O2.
Too much light can be detrimental to plants, if the root zone support structure for nutrient, O2, root zone temperature and H2O is insufficient. Understanding your systems limits will ensure you have the best lighting for your plants.
The Significance of Light
Without light there is no photosynthesis. Without photosynthesis, plants die. This process of taking energy from light and converting it into chemical energy is a critical part of the plant growth process, regardless of whether the conditions are natural or artificial. So, your LED grow light spectrum has to be carefully designed to ensure that this process takes place. You will need to identify the exact wavelengths of light that are required by each species of plant during its lifecycle so that you can manage your crops adeptly – such as extending the lifecycle by creating an extra-long spring or summer.
“The changing of the seasons for a plant is key to its survival and all plants, where seasonal changes are significant, respond in a similar way,” adds Matcham. “In spring, dormant plants will grow leaves and get bigger and, as the plant establishes itself, may grow a flowering stem that will eventually, by autumn, produce seeds for the plant to reproduce the following year.”
Some plants produce seeds underground as bulbs or tubers, others like Rocket produce flowers and eventually seed pods, in food production this is called bolting. This is undesirable as the stems; the plant shouldn’t flower as the stems use valuable energy and the quality of the crop is reduced by the waste and cost of separating the stems and flowers from the leaves.
However, in potatoes, a fast growth and early flowering could produce a very efficient crop. Light is the most significant of the cardinal environmental factors that manage these different growth speeds and cycles so it is critical to ensure that any environment uses the exact recipe of wavelengths to ensure the best crop. It is also important, of course, to balance this light with the other eight cardinal environmental factors to ensure that they are all working in harmony. This will produce the best and most energy efficient crops.
Image: Light Science Technology – Reach in controlled environment growing chamber
“At Light Science Technologies, we can recreate any environment on Earth where plants grow, we can recreate artificial light conditions that mimic all the requirements for any particular species of plant,” says Matcham. “Then we can reproduce that light in an energy efficient long-life growing luminaire that’s supported by our big data environmental monitoring systems and growing environmental controls that are being developed for the grower.”
In the past, growers were limited in their choice of light source and how they managed the grow light spectrum. Today, the variety of light sources and solutions, particularly LED grow lights, allow you to customise and enhance your light to ensure the right spectrum and results.
The Right Light Spectrum
There are plenty of ways in which light spectrum and the different colours can transform your crop growth. Your grow light spectrum can influence multiple factors for your plants, from fruiting to flavour to colour, plant health, weight and nutrition. This is why it’s important to activate your plant responses in the right way using the right LED grow light spectrum. This balance can be achieved through trial and error, or by working with a partner that understands the impact of grow light spectrum and has already developed definitive light spectrum best practice.
Image: Visible wavelength range and its impact on plant growth
The key light spectrum wavelengths to consider are UV, blue, green, red, and far-red. The UV light spectrum is between 100 and 400nm is considered important for plant growth. This grow light spectrum is associated with helping plants to produce specific substances that improve flavour and crop quality. The blue light wavelength at 400-500nm is connected to growth and flowering and can improve the quality of certain types of plant. When used in conjunction with other grow light spectrum wavelengths, blue light can help you tightly manage growth cycles. The green light spectrum from 500-600nm is not seen to be as useful as the other wavelengths for plant grown but it is valuable for photosynthesis and research has found that green light can ‘actually promote extension growth’ and that the results it offers depend on intensity and type of crop. Then, red light at 600-700nm is one of the most efficient grow light spectrums for photosynthesis and plant biomass growth and is one of the most efficient spectrums for plant growth and energy consumption. Finally, far-red radiation from 700-800nm can promote extension growth and ‘influences the size of the leaves, the length of stems, and ultimately the height of plants.’
The right partner will work with you to create an LED grow light solution that achieves optimum light quality, energy savings and yield. Work with a trusted partner who can create the right recipe for your environment and who has the latest technology and science at their fingertips, ready to help you shift your yield forwards. LED grow lighting can see you achieve returns on investment (ROI) that help you grown more for less.
We can help you transform your greenhouse lighting with the right technology, expertise and science. Contact us on 01332 410601 to speak to one of the team.
