Sustaining Food Security with Vertical Farming Lighting

Vertical farming is a method of stacking crops in vertical layers. It aims to save on the land and improve the efficiency of traditional outdoor crop production. As interest in urban farming continues to increase, so is the demand for vertical garden lighting. The low level of light penetration into the plant canopy makes it difficult to produce sufficient crops in limited spaces. Vertical lighting helps solve various problems associated with traditional land-based growing techniques.

What is lighting, and what type of lighting do we use for vertical farms?

Lighting is the application of electromagnetic radiation to generate signals in an object, such as plant leaves. Light sources can be natural (e.g., solar illumination, lightning, the Sun), artificial (e.g., LEDs, tungsten lamps, lasers, arc lamps), or outside the earth’s atmosphere (e.g., cosmic microwave background). When sunlight strikes objects, some of its photons are absorbed by the material while others are reflected or transmitted. The light scatters in all directions to form a defined space with a specific intensity and spectral composition.

How vertical farming Lighting Works

In vertical farming, LED lighting with its high proportion of red light is more effective in promoting photosynthesis than sunlight, which has a higher proportion of blue/green light. 

Light Emitting Diodes (LEDs) are the ultimate choice for vertical farming lighting and offer unique energy-saving, spectral optimization, and heat management possibilities. Light-emitting diodes can emit a single spectral bandwidth or full-spectrum light depending on the crop’s need. 

One can vary the spectral distribution by altering the chemical composition of the semiconductors in each LED, allowing for complete customization for specific plant types. For example, zinc selenide emits a blue-green light that is efficiently absorbed by chlorophyll A and B, while zinc sulfide produces a bright yellow light reflective to plants. 

Customization gives the option of covering a broad spectrum similar to full sunlight or focusing on specific wavelengths to create enhanced plant growth or flowering with increased vigor, increased nutrient uptake, and improved flavor.

There are five primary colors in the light spectrum visible to humans: Red, orange, yellow, green, and blue. Each color has a different wavelength range. This variation in wavelengths affects how plants grow. For example, red absorbs light while blue is good at penetrating leaves allowing for deeper light penetration. 

The root growth rate is negatively correlated with blue exposure and positively correlated with red exposure. Consequently, exposure to both can increase anthocyanin concentrations in root tissue. 

In addition to the primary colors mentioned above, white light has its uses in lighting greenhouses because it provides a broader range of wavelengths. White light can also be more aesthetically pleasing than colored lights. 

Vertical farming Lighting Systems

Artificial Light

Artificial lights are currently applicable in vertical farms all over the world. Some vertical farming methods utilize natural sunlight when it is available via skylights or windows, while others incorporate artificial lighting when natural light is unavailable. Artificial lights also work best in low-rise buildings with large rooms easily reached with light fixtures.

Horticultural lighting, in general, is designed with a specific spectral output in mind. However, by changing the semiconductor material composition in LEDs, it is possible to alter the spectrum emitted by each diode. 

Sunlight Simulation (SUN)

Sunlight simulation (SUN) is the only choice of light in high-rise buildings without windows. Using sunlight simulation lighting instead of artificial lighting requires less energy and offers excellent results. Sunlight can also be allowed to filter through windows or skylights to provide vertical farms with natural light. Since the spectral distribution of sunlight varies throughout the day, it is essential to provide lighting that simulates full-spectrum light.

Why LEDs are Suited for Vertical Farming Lighting

An important consideration to make when growing plants indoors is the cost to power the grow light bulbs. Compared with other lights used to brighten indoor spaces, such as incandescent bulbs, LED grow lights are extremely efficient. In addition, vertical farming allows more growth of plants without any additional input of money for power costs.

Vertical farming can also increase the production yield from each plant. Furthermore, every inch of the indoor space that would otherwise be unused bears a plant using vertical farming techniques.

Another major benefit of using LEDs is controlling the atmosphere inside of a building where plants are being grown. With one entrance for air and another for exiting air, an indoor growing system can allow air circulation throughout the entire area. This benefit enables all areas to have equal access to oxygen, thus removing any stale air.

One can also program the lights used for vertical farming to turn on and off at particular times during the day, simulating periods of rainfall and sunlight. As a result, indoor plants can grow quickly and sturdily without being exposed to extreme changes in climate.  

The lights are especially beneficial to plants that require exposure to sunlight, then periods of rest in the dark for some time. In addition, farmers can employ the pattern to trick plants into thinking that natural seasons are occurring. For instance, the lights can simulate the four seasons using this method. This ability to create different conditions for plants using a combination of lights and other elements is a major benefit to vertical farming.

Final Thoughts

Vertical farming is not a new concept. It’s quite popular in many parts of the world. The biggest advantage of vertical farming is the high crop yield per hectare and low labor costs. In addition, watering and weeding can be automated to a large extent. It also helps in avoiding the wastage of resources like fertilizer and water.

Lighting for vertical farming is a very important part of this concept. The indoor conditions in a vertical farm are easily controllable, and a farmer can obtain a high yield per product unit. But it requires high-intensity lighting, which can produce the full light spectrum needed for plant photosynthesis. A farmer can use specialized LED lights for this purpose. The LED lights are available in different configurations depending on the requirement of spectrum and intensity.