While the internet can be a great thing, false information can spread very quickly on it. I’d like to take some time today to clear up some common misunderstandings and misconceptions about aeroponic cloning, and properly educate everyone reading this. At EZ-CLONE, we have been cloning plants 365 days a year for the last 18 years. Should you have any questions or concerns, please do not hesitate to ask us for assistance. You can find our contact information below.

In the world of plant propagation, many factors determine the success of your cloning cycle. From traditional methods of cloning in a medium, to the most advanced aeroponic methods, the outcome of a cycle is reliant upon one’s ability to control the environment and by creating the perfect conditions for that particular species and strain.

Plant propagation relies on the convergence of three critical factors; moisture, oxygen and heat. No matter what method of propagation, these three principles of cloning always apply. Cuttings yearn for a warm, moist, oxygen-rich environment. Unfortunately, so do bacteria and pathogens, the the leading causes of problems with plant cloning.

Bacteria and pathogens can be controlled by two methods:

1. Creating a hostile environment to the bacteria via temperature control
2. Using additives that combat the bacteria and pathogens on a molecular level.

In years past, it was a common belief that when cloning in an Aeroponic System, better results were achieved with lower reservoir temperatures because there was a significantly decreased risk of bacterial infection. In the past, even we at EZ-CLONE recommended cloning between 68 and 75 degrees Fahrenheit. By keeping the reservoir temperature lower, bacteria and pathogens are discouraged from growth, resulting in higher success rates.

However, this method is a double-edged sword. By making conditions inhospitable for bacteria, you’ve also made a more hostile environment for your cuttings, which can result in undesired consequences, such as prolonged rooting times.

While many folks believe the best way to lower water temps is by placing a frozen 2 liter bottle into their reservoir(s), this can also transfer harmful bacteria into their system(s). On top of that, this method requires frequent bottle swaping, and doing such causes a reoccurring fluctuation in water temperatures, something that cuttings DO NOT prefer.

The problem with the above methods is that instead of concentrating on creating and maintaining the perfect conditions for root development, a greater emphasis is placed on keeping bacteria at bay. This results in a less-than-optimal environment for root growth, meaning we need to reevaluate our priorities.

After extensive testing and research, we at EZ-CLONE have determined that warmer reservoir temperatures can accelerate rooting times. By developing an additive to directly combat bacteria and pathogens, which we named Clear Rez, we could open up a broader spectrum of acceptable cloning temperatures. With the use of Clear Rez, 100% success rates have become the norm at 85 degrees Fahrenheit, depending on species and strain. Remember, that there are always multiple solutions to any given problem, and finding the most practical solution is what learning and growth is all about.

If you do decide to use an antimicrobial additive in your reservoir, make sure to read the directions CAREFULLY, as there is a prescribed method of addition that should be followed very closely.

EZ-CLONE has spent several years extensively researching the effectiveness and benefits of using an air pump in aeroponic systems. We have found no discernible benefits to using an air pump, in direct contradiction to several common myths. The air pump simply can become a vessel for introducing harmful bacteria and pathogens into a closed system.

Remember, we are specifically talking about aeroponic cloning, which means our cuttings/roots are suspended in midair. They are already absorbing all of the oxygen they require, which means an air pump is redundant. Furthermore, as the system cycles water via spray and reaccumulation, the water gets additional oxygenation. Air stones and air lines are just another thing to clean, potentially housing harmful bacteria. On your next cloning cycle, eliminate the air line and see for yourself. Results don’t lie!

Resources:

Want to get in touch with person? They can be reached via the following methods:

1. Website: http://www.ezclone.com/
2. Phone: 916-626-3000
3. Email: info@ezclone.com

Walk into your typical U.S. or U.K. grocery store and feast your eyes on an amazing bounty of fresh and processed foods. In most industrialized countries, it’s hard to imagine that food production is one of the greatest challenges we will face in the coming decades.

From the 1960s through the 1980s, international initiatives referred to collectively as the Green Revolution dramatically increased food production, largely by breeding crop varieties that were able to take advantage of man-made fertilizer and developing powerful pesticides and herbicides. But as we intensified agriculture, we also intensified its environmental impacts. They include soil erosion, reduced biodiversity and the release of greenhouse gases that drive climate change.

However, we will need to almost double food production within just three decades, because by the year 2050, the human population is projected to grow from 7.5 billion to nearly 10 billion. All this production will need to happen in the face of increasing drought, herbicide and pesticide resistance, and in a world where the best cropland is already being farmed. Realistically, our ability to continuously push these systems to produce more crops year after year has largely stagnated, and is not keeping pace with rising demand. New innovations are needed to change the way we grow food and make it more sustainable.

I am part of a new crop of scientists (Editor’s Note: Pun intended) who are harnessing the power of natural microbes to improve agriculture. In recent years, genomic technology has rapidly advanced our understanding of the microbes that live on virtually every surface on Earth, including our own bodies. Just as our new understanding of the human microbiome is revolutionizing medicine and spawning a new probiotic industry, agriculture may be poised for a similar revolution.

Microbes in soil from a mountainside in eastern Washington. Pacific Northwest National Laboratory/Flickr,
CC BY-NC-SA

In nature, plants coevolve with the microbes that live in their rooting zones (or rhizosphere), on their leaves, and even inside their cells. Plants provide microbes with food in the form of sugars, and microbes make nutrients available to the plants and help prevent disease. But as we added more and more chemicals to our fields and tilled our soils, we broke the close connection between plants and microbes by killing many of these beneficial organisms.

A few years ago, I decided to apply my expertise in soil microbes to improving agriculture. Of all things, I was actually inspired by doctors’ surprising success in using human fecal transplants to cure a chronic and often deadly bacterial infection called Clostridium difficile. By simply transplanting the fecal microbiome from a healthy person, the disease was cured, permanently! Could the same approach work in agriculture?

Along with my close collaborator at Colorado State University, Dr. Colin Bell, I set out to develop a microbial technology that increased the availability of phosphorus, a critical nutrient that plants need to grow. Farmers typically provide phosphorus to plants by applying fertilizer. But, when it is added to soils this way, up to 70 percent of it becomes bound to soil particles that plants can’t access.

Microbes can unlock phosphorus and other micronutrients from these particles so that plants can use them. We developed a combination of four bacteria that are exceptionally good at making phosphorus available to plants, leading to bigger, healthier plants. They do this by releasing specialized molecules that break the bonds between phosphorus and soil particles. To get this technology into the hands of farmers who can use it, we launched a startup company called Growcentia and started selling our first product, which is called Mammoth P. Mammoth P, which is a microbial product, increases plant growth by releasing phosphorus, an important nutrient, from soil particles so that plants can take it up and use it.

I’m not alone in thinking that microbes can help feed the world. Many other startups are working on microbial technologies for food production, including AgBiome, Indigo, Maronne BioInnovations, and New Leaf Symbiotics.

The world’s biggest agriculture companies are also investing heavily in biological solutions. For example, Monsanto recently invested USD $300 million in an alliance with the biotechnology company NovoZymes. Why is Big Ag getting into microbes? These companies recognize the problems caused by chemical-based agriculture and want to be part of the future. Clearly, they see the potential to make money by giving farmers new tools to produce food more efficiently and with less impact on our planet.

Growcentia focuses on soil microbes that increase nutrient efficiency and uptake, but microbes can also enhance agriculture in many other ways. Some companies are focused on commercializing microbes that have been shown to suppress plant responses to drought, which ironically tricks them into continuing to grow through dry conditions. Other companies are developing microbial products that protect plants from disease and pests. Microbes can even influence the timing of flowering. The possibilities are endless.

Beneficial microbes have long been used in agriculture. For decades, farmers have been adding nitrogen-fixing bacteria and symbiotic fungi called mycorrhizae to their legumes in order to help plants acquire nutrients. But many older products contain undefined mixtures of microbes and make broad claims about how they enhance plant growth. They’ve largely earned a reputation as agricultural snake oil, which makes it hard to convince farmers to adopt the next generation of beneficial microbial technology.

Farmers treat soil or legume seeds with bacteria that can take nitrogen, an essential plant nutrient, from the air and make it available to the plant. The bacteria form nodules on the plant roots. Terraprima/Wikipedia, CC BY-SA

Until recently, we could observe and study only microbial species that were easily culturable in the laboratory using traditional approaches, which represent a tiny fraction of the microbial world. But now we have new methods for developing microbial technology that is precisely targeted towards specific functions. We can examine microbial genes via sequencing or analyzing their function using high-throughput screening methods to find microbes with particular attributes. We also can genetically-engineer microbes to produce new strains with the characteristics we want. Or we can even synthesize entirely new species from scratch.

It’s also one thing to produce beneficial microbes that enhance plant growth in experimental greenhouses. It’s another to develop a microbial technology that can be produced at large scale, transported and stored in harsh conditions for long periods of time, and then function flawlessly in a wide range of soils and climates. For that reason, many products that are in the pipeline now still have a long way to go before they reach a farmer’s field.

When people think of microbes, many of them picture germs and disease. But the reality is that many microbes are beneficial, and we literally could not live without them. For too long we have ignored the benefits of a healthy microbiome in agriculture. The explosion of interest in beneficial microbes for food production is exciting and portends a future when agriculture is less reliant on chemicals. The future of food is below our feet in the invisible universe of the microbial world.

Resources:

Want to get in touch with person? They can be reached via the following methods:

1. Website: https://mammothmicrobes.com/
2. Email: info@growcentia.com
3. Phone: (970) 818-3321

As the cannabis industry continues to grow, national attention is often negatively directed towards the industry’s environmental footprint. Unfortunately, this is not without good reason. Because policies often force cultivation indoors, cultivators are virtually required to use energy-intensive equipment to simulate real-world ecological conditions. Lighting, ventilation, dehumidifiers, air conditioning, CO₂, drying, and transportation are just a few parts of cannabis cultivation that require significant energy inputs. Currently, cannabis is the most energy-intensive agricultural commodity and remains to be one of the most energy-intensive businesses per square foot.

The energy demands of indoor cannabis cultivation are the most significant contributor to the industry's environmental footprint. Although policies force grows to go indoors, there are no industry-wide mandates to impose energy-efficiency standards. It is common for cultivators to use high-pressure sodium (HPS) lights to produce desirable growing conditions, whose illumination is on par with those found in an operating room, and 500 times higher than that recommended for reading. Although some cultivators use energy-efficient LED lights, their overall environmental benefit within the cannabis industry has yet to be determined. The difficulty with LEDs is that, while they consume less energy, they cause grow cycles to take longer, potentially averaging out or raising overall energy expenses.

A study published in 2012 estimated that energy consumption by the cannabis industry accounts for 1% of the national electricity use or $6 billion worth of energy – and that was in 2012. The study also reported that, on average, the cost of production in electricity is approximately $2500 per kilogram of finished product, and one kilogram of processed cannabis results in 4600 kilograms of CO₂ emissions; which is the equivalent of driving across the US 11 times in a 44-mpg vehicle.

Current statistics are just as alarming. In Boulder County, the average electricity consumption of a 5,000 sq. ft. indoor cannabis facility is 41,808 kilowatt-hours per month. For comparison, the average household uses 630 kilowatt-hours per month (or 1.5% of the aforementioned grow). From 2015 to 2016, cannabis cultivation and processing areas in Boulder County increased from 114,197 sq. ft. to 170, 341 sq. ft., thus causing a 71% increase in energy expenditure.

Due to the federal government’s stance opposing cannabis, producers are not able to reap the benefits that other industries do when implementing energy-efficient practices. Cultivators and producers receive no tax breaks, nor do they have the ability to become USDA organic. Thus, any incentive to switch to more energy-efficient equipment is done purely on the basis of market supply and demand.

The aforementioned factors, in addition to the current overall lack of governmental support, have led to the development of state-based certifications and incentive programs.

In Oregon, Eco Firma Farms has made outstanding improvements to their grow, allowing them to exponentially reduce their environmental footprint and bottom line. Working in tandem with Energy Trust of Oregon, Eco Firma Farms has made multiple improvements that have led to a quick and qualitative ROI in addition to reducing their environmental footprint. These energy-efficient improvements returned an estimated annual savings of $63,000, and incentives received for updating their operation totaled $99,800. Eco Firma Farms currently operates on 100% wind-powered renewable energy and practices only organic pest control. Last year, they were awarded Portland’s General Electric (PGE) Green Mountain Energy Gold Certification, and are on track to receive Platinum Certification in 2018.

Programs and efforts to produce more environmentally friendly cannabis are starting to develop throughout the industry. Denver currently has the goal to shrink their greenhouse gas emissions 80% by 2050 through boosting the use of renewable energy. In California, MITU Resources, Inc. is planning the commercial introduction of the company's licensed Wind Shark, a self-starting vertical-axis wind turbine. The integration of the Wind Shark into the CA cannabis sector, it is hoped, will reduce a cultivator's daily energy expenditure by 10% and their bottom line.

As is the normal trend of the cannabis industry, it grows at such an exponential rate that supporting industries have difficulty keeping up with it. Energy-efficient practices and standards are no exception to the rule. Independent state energy certifications and product labeling ensure that companies are making their achievements and impact visible to consumers, thus spreading positive program awareness. Indubitably, the cannabis industry will continue to grow before industry-wide energy standards are implemented. However, steps taken now will have a significant impact on reducing the industry's environmental footprint.

Resources:

Want to get in touch with Stephanie? They can be reached via the following methods:

1. Website: https://www.cannabistech.com/

You’ve probably encountered HVAC systems. HVAC is an acronym for Heating, Ventilation, Air Conditioning. They’re virtually everywhere: air ducts lacing supermarket and warehouse ceilings, bulky equipment outside or atop office buildings and sports stadiums, or furnaces sitting in the garage or basement of your home. HVAC systems are found commonly in our lives and are there to provide comfortable indoor environmental conditions in the form of temperature and air quality. Studies conducted in office buildings showed that ambient indoor air temperature as well as indoor air quality have significant effects on the productivity and well-being of workers. *

This isn’t true just for people, however. Air quality is also critical for plants. Indoor climate conditions such as temperature, humidity levels, and 0₂ and CO₂ levels are crucial in dictating whether plants will thrive. Growing in enclosed growing facilities means that the grower is responsible for providing the right conditions for plant development.

HVAC systems, which vary drastically in their form, size, capabilities, infrastructure, and prices, provide 3 main functions for a closed growing facility:

1. Heating: Higher temperatures in a growing facility may be required depending on external conditions. A heat pump transfers heat from the outside environment inside, utilizing a refrigerant cycle. Many growing facilities are also commonly heated with alternatives where water or air is heated using boilers, furnaces, burners, etc.
2. Ventilation: This component circulates the indoor air and replenishes it.
   1. Air circulation mixes the air in the growing facility, producing more uniform conditions of temperature and humidity within the space. Climate uniformity in cannabis cultivation helps produce a uniform crop. It also prevents humid microclimates, preventing the development of mold and plant diseases. That being said, many HVAC systems often do not provide sufficient circulation to prevent these problems, and may require additional equipment such as fans to do the job well.
   2. Air exchange exhausts the indoor air to the outside and inputs fresh air from the outside. Depending on the way the system is outfitted, this exchange can provide other unintended consequences including humidity and temperature fluctuations, depending on outdoor conditions. Some growers opt not to ventilate with outside air, allowing for CO₂ supplements to be used more efficiently. Different filters can be built into the ventilation system to help remove odors, dust, moisture, airborne bacteria or spores, and more.
3. Air Conditioning (Cooling): Facilities often need to be cooled in order to reduce the large amount of heat generated by growing equipment (including grow lights, ballasts, dehumidifiers, and CO₂ generators). The air conditioning component of most HVAC systems in a greenhouse utilizes a water chiller which supplies cold water that absorbs heat as it runs throughout the greenhouse. Chillers also have the capacity to produce hot water which makes them versatile options for growing facilities that require both cooling and heating throughout the year. Other cooling alternatives commonly used in cultivation facilities include misting and pad-and-fan systems.

Note from the author: A byproduct of operating the HVAC system is humidity reduction. In our next article we will elaborate on this topic - stay tuned!

The advantage of HVAC systems is that they provide an integrated solution – 3 functions in one system. The system is programmed to a set point and its components are automatically operated. However, HVAC systems can be pricey and involve quite a bit of infrastructure. When designing a growing facility which will utilize an HVAC system, it is important to define the required conditions for successful growth and calculate the size and characteristics of the system which will be able to meet these needs.

Resources:

Want to get in touch with DryGair? They can be reached via the following methods:

1. Website: https://www.drygair.com
2. Phone: +972-9-7730980
3. Email: info@drygair.com

In commercial production, artificial light sources are used in a variety of ways:

1. Replacement lighting - complete replacement of solar radiation for indoor growth rooms and growth chambers.
2. Supplemental or production lighting – used in greenhouses to supplement periods of low natural light.
3. Photoperiod lighting – used to stimulate or influence photoperiod dependant plant responses such as flowering or vegetative growth.

The need for and quality of artificial illumination required is determined by a number of factors including:

1. Light requirements of the species being grown.
2. Natural daylength.
3. Average hours of sunlight.
4. Sun angle and intensity (latitude and weather).
5. Amount of structure-induced shading.

Because sunlight is a free input, it is usually best to take maximum advantage of the ambient solar conditions. Seldom has it been shown that 100% artificial lighting is economically viable for legally grown commercial crops. Even though it is highly variable, sunlight is far more intense than any commercially practical artificial sources and it is has a broader, fuller spectrum of photosynthetically active wavelengths.

Editor’s Note: This article was written when cannabis was not commonly grown on large, legal scales.

When constructing growing environments where the majority of lighting is from artificial sources, it is normal to mix lamp types to achieve a more balanced spectrum, and many configurations have been devised and studied. However, there remain practical difficulties in achieving a uniform distribution of light when using mixtures of lamp types.

For commercial greenhouse production, supplemental lighting is most beneficial in areas that receive less than 4.5 hours average daily sunshine. In many greenhouse growing regions this occurs in winter as a result of the combination of high northern or southern latitudes and overcast weather. For example, parts of Washington, Oregon, and southwestern British Columbia, average just 2 – 2.5 hours of sunshine per day during the winter months, and because of the relatively low sun angle, the overall intensity can be as low as 5% of summer levels.

In lighting terminology, the word ‘lamp’ refers to the light bulb or tube, and the word luminaire refers to the entire light fixture: lamp + reflector + ballast + housing. When discussing and comparing light sources it is common to just refer to the lamp types. However, most specialized lamps require custom housings, ballasts, and reflectors.

Consequently, for a given lamp type, there may be several configurations of luminaires available. Some are designed specifically for horticultural use, and others for different applications. It’s important to remember that the luminaire type, and the reflector design in particular, play a very important role in the horticultural effectiveness of the lamp.

A perfect artificial light source would provide 100% conversion of electrical energy into light, in a spectrum optimally balanced for plant growth. In reality, no such light source exists, not even the sun. Therefore, when evaluating artificial light sources, several factors and compromises must be taken into account. Lamp efficiency, lifespan, intensity, spectral quality, cost, and electrical requirements must be weighed against the crop demands and the intended application before selecting any supplemental or solar replacement source.

Conventional horticultural light sources can be grouped into three categories:

1. Incandescent
2. Fluorescent
3. Discharge

Editor’s Note: At the time this article was written, LED horticulture lights were largely experimental and not useful at a commercial scale. Since that time, however, some LED horticulture lights have shown significant promise.

Incandescent lamps typically emit light as a result of the heating of a tungsten filament to about 2500 Celsius. At this temperature, the emission spectrum from the filament includes a substantial amount of visible radiation. Only about 15% of the energy (watts) applied to an incandescent lamp is radiated in the PAR (photosynthetically active radiation) range of 400-700 nm. 75% is emitted as infrared (850-2700) nm, and the remaining 10% is emitted as thermal energy (> 2700 nm).

Since they are not very light efficient and they have a relatively short lamp life, incandescent lamps are usually not the most effective radiation sources for providing supplementary light for photosynthesis. They are, however, useful for phytochrome-dependent photoperiod control since they are relatively inexpensive to install and operate, they can be cycled on and off frequently, and they produce large amounts of red and infrared radiation.

This is why incandescent sources are often the lamp of choice for night break, and long-day lighting applications, particularly when other supplementary lighting sources are not installed. Typically, incandescent lights are used to break the night into two or more short-dark periods, thereby stimulating a long-day growth and development response in the crop. This may be used to promote flowering in long day species such as asters, azaleas, and fuchsias, or to delay flowering in short day species such as chrysanthemums, begonias, and poinsettias.

Since plant photoperiod response occurs under relatively low light intensities, less power is needed for photoperiod lighting than for supplemental lighting. The long standing recommendation for maintaining vegetative growth in chrysanthemum crops has been to place strings of 60 watt bulbs spaced 1.2 meters apart and suspend them 1.5 meters above the crop. This will provide sufficient photoperiod lighting for a 1.2 meter bed or bench.

Similarly, any combination of incandescent lamp wattage, spacing, and mounting height that can produce an output of at least 10 foot-candles evenly on the crop will work. This corresponds to about 16 electrical input watts per square meter (rated bulb wattage divided by the area illuminated). Special reflector bulbs are available to focus most of the radiation downwards or do-it-yourself reflectors are often fashioned from aluminum foil pie plates.

Unlike incandescent lamps, which emit light from the heating of a metal filament, fluorescent lamps produce light from the excitation of low pressure mercury vapor in a mixture of inert gases. A high voltage differential at the electrodes on opposite ends of the lamp tube produces an arc through the gas mixture exciting the mercury ions, which in turn emit short wavelength (primarily UV) radiation as they drop back to a ground state. Special fluorescent coatings on the glass tube walls are activated by this short wavelength radiation producing a discharge of visible spectrum radiation from the lamp. By altering the composition of the fluorescent coatings, variations in spectral output are accomplished.

Fluorescent lamps are more light efficient than incandescent lamps and they have a much longer life span. They also run cooler and produce a fairly balanced spectrum in the PAR range. They operate best in warm temperatures with peak light output occurring when the lamp wall reaches about 38C. As the temperature decreases, light output falls dramatically to only 50% when the lamp wall temperature is 16C. Light output also declines as fluorescent lamps age, falling to about 60% after 10,000 hours.

Fluorescent lamps are available in three load types:

1. Normal output 400 mA.
2. High output 800 mA.
3. Very High output 1500 mA.

One disadvantage of fluorescent lamps is their relative bulk in relation to output. Even the very high output fixtures and the new slimmer T8 tubes, when configured in sufficient densities for supplemental lighting, can cast considerable shadows that can interfere with ambient lighting. They are however, useful in growth chambers and particularly in multiple tier applications since their relatively cool operating temperatures allow them to be mounted in close proximity to plant surfaces.

Fluorescent lamps are available in a range of spectral qualities. Relatively inexpensive cool white lamps are fine for supplementary lighting, and ‘full spectrum’ lamps are available for replacement lighting applications.

Modern high intensity discharge lamps are similar to fluorescent lamps in that they introduce an electrical arc into an elemental gas mixture. This produces a spectral discharge that is characteristic of the elements in the arc. However, they differ from fluorescent lamps in that no fluorescing powders are used on the lamp glass, and the elemental gases are heated under much higher vapor pressures and temperatures.

The light intensities and efficiencies obtained by high intensity discharge are higher than either incandescent of fluorescent lamps. The two most common discharge lamps used in modern horticulture are metal halide and high pressure sodium lamps.

Metal halide lamps use mercury vapor in a quartz arc tube and various iodide mixtures of sodium, thorium, or thallium.

The electrical arc vaporizes the halides, heating them to a plasma state, whereupon they emit line spectra characteristic of the elements in the plasma. Metal halide lamps produce a relatively full spectrum of white light that is often preferable to the yellowish light of high pressure sodium when used in public or retail horticultural environments.

They provide the best overall spectral distribution of all horticultural lamps, but are not quite as efficient in energy conversion as high-pressure sodium lamps in the PAR range, particularly in the yellow-red spectra.

High pressure sodium has become the most popular lamp type for commercial supplemental lighting in horticulture. High pressure sodium lamps produce light from an arc-induced discharge in a mixture of sodium vapor and mercury vapor. The emission spectra is highly concentrated in the yellow-orange-red range (500-650 nm) but is fairly low in the blue range.

Used as a replacement light source, HPS lamps may require supplementation with fluorescent, mercury vapor, metal halide, or other light sources high in blue light. However, they are fine as a supplemental source since adequate amounts of blue light are usually available from ambient light to sustain blue-light-specific plant morphogenic responses.

HPS lamps have a long life, and are available in a range of wattage sizes as well as ballast/ reflector configurations optimized for horticultural production.

Low pressure sodium lamps which, although more efficient in their conversion of watts to lumens than HPS, produce a spectral distribution so narrow that they are of little horticultural use.

The following table summarizes the relative radiant efficiencies for the standard illumination sources used in horticulture.

The degree of growth uniformity in a crop is influenced directly by the uniformity of light falling onto the crop canopy. The manufacturers of horticulture luminaires often recommend specific grid and spacing patterns for various intensities and lighting configurations.

These are determined by the specific lamp output, crop requirements, and luminaire reflector designs. Often, an overlapping pattern is designed with some additional modifications to lamp placement and density at the crop margins to produce the most uniform lighting over the entire cropping surface.

It has long been accepted that it is more efficient to provide a lower amount of irradiation over a longer period than a high amount over a short period. For example, it is usually better to light a crop at 5 W·m^-2 for 18 hours, than at 10 W·m^-2 for 9 hours, provided there are no photoperiod requirement conflicts. Not only do the plants use the light more efficiently, but the total number of luminaires and electrical service loading can be reduced, thereby reducing capital investment costs.

It has also been shown that the maximum incremental benefit of supplementary illumination occurs when the plants are lit beyond the daylight period, so lighting at night is generally more effective than lighting during the day period.

During periods of low ambient light levels, it is a common strategy to light during the day wherever levels fall below a predetermined set point, and to extend the lighting duration period to the maximum recommended for the crop. For example, cucumbers and roses can be illuminated for 24 hours per day, while tomatoes and most bedding plants should only be lit for 16 - 18 hours to avoid problems with flower delay.

In greenhouses, supplementary light levels have been suggested ranging from 3 W·m^-2 for ferns and other low light crops, to 20 W·m^-2 for vegetable crops and propagation areas.

Resources:

Want to get in touch with Argus? They can be reached via the following methods:

1. Website: http://arguscontrols.com/
2. Email: sales@arguscontrols.com