Plants rely on sunlight for growth and development. Optimizing the light plants receive can be one of the most challenging factors for greenhouse crop production. Seasonal and daily changes to natural light mean growers need to supplement with the right light, in the right place, in the right quantity, at the right time. As with everything, there are pros and cons to supplemental greenhouse lighting strategies. But growers who are able to optimize the supplemental light they provide to plants can eliminate seasonal changes in production cycles, increase crop production, ensure crop consistency and grow quality plants year-round.

What is Supplemental Greenhouse Lighting?

There are two key lighting components to consider in a greenhouse environment: the natural seasonal light levels in your facility and the daily light requirements of your crop. Supplemental greenhouse lighting is used to increase light levels at times when natural light is low, such as outside of daylight hours, over the winter season, and on gloomy summer days.

Supplemental lighting is a topic that concerns all greenhouse growers, but what are the pros and cons?

Pros and Cons of Supplemental Greenhouse Lighting

Pros:

1. Meeting Your Target Daily Light Integral (DLI) 

   For most crops, there is a linear relationship between the total amount of light your plants receive and their growth. The daily light integral (DLI) is the sum of all photosynthetically active radiation (PAR) received by plants over the course of a 24-hour day. DLI is measured in moles of photons (mols) per square meter per day. Generally, the more photons – or the higher DLI – plants receive, the better the overall quality and production rates of plants.

Many greenhouse growers are choosing LEDs for their supplemental lighting to increase DLI and eliminate seasonal shifts in light. This helps them increase year-round yields and keep production output stable for their customers. Andrew Fuller, Technical Director, at the UK’s Bridge Farm Group, noted:

It’s important to note that each plant species has an optimal light intensity above which light absorption and photosynthesis are not as efficient. Your lighting provider should map out a greenhouse lighting plan that considers the needs of all your individual crops.

2. Year-Round Production

   With supplemental lighting, you are not bound to the seasons. Even in the dead of winter, with a high-quality LED grow light you can mimic ideal summer growing conditions. This will help you grow more plants faster and fit more grow cycles into a year, driving more profit for your business. Learn more in our eBook on producing high-quality, profitable food crops consistently throughout the year.
    

3. Enhanced Spectrum and Variable Spectrum Control

   Light works in synergy and the spectra in your supplemental lighting can help you achieve different goals at different phases of growth, from root establishment to plant finishing. HPS lighting, however, has a fixed spectrum and is not necessarily optimized for PAR and plant cultivation.

Intelligent LED lighting and variable spectra controls can deliver the right light intensity (quantity), in the right ratio of wavelengths (quality), tuned to the DLI of your choosing (duration), and focused evenly on your plants (distribution). By harnessing these 4 key light properties, today’s grow facilities are ensuring optimal light exposure for their crops.

Cons:

1. Upfront and Operating Costs

   There is an upfront cost to adding supplemental greenhouse lighting, as well as the operating costs of running your lights day-to-day. There are, however, a few ways to mitigate those costs.

2. Rebates & Incentives

   Generous rebates and incentives are being offered to growers who implement energy-efficient LEDs. These funds are being provided by government and utility organizations to encourage the switch from traditional lighting. They can help drive down the purchase price and considerably shorten your buy-back period. You may be surprised by the size of the rebates and incentives currently on offer. Download our eBook for the United States or Canada to find out what’s available to you.

3. Energy Savings

   The US Department of Energy acknowledges that “LED is a highly energy-efficient lighting technology and has the potential to fundamentally change the future of lighting ….” LEDs use less wattage than HPS for a higher or similar level of light, leading to direct energy savings. Additionally, LEDs radiate very little heat, so energy isn’t wasted on cooling the space and plants. Crops also transpire less under LEDs, so dehumidification requirements are reduced. A combination of these factors helped US cannabis producer, Experience Organics, achieve a 50% reduction in energy costs with Heliospectra LED lighting and controls.
    

4. Maintenance

   Unlike natural sunlight streaming through your greenhouse windows, HPS or LED lighting will need some maintenance and upkeep. While LEDs have a lifetime rating of over 50,000 hours, HPS lamps have a life expectancy of 24,000 hours and can experience a loss of efficacy within as little as 5,000 hours.

When it comes to cleaning, our MITRA is IP67 rated and can be quickly hosed down, saving you time and effort, while HPS lamps and reflectors require regular, careful cleaning. Plus, LEDs don’t require bulb, ballast, or driver replacements, further driving down costs and using fewer consumables. 

Summary

While supplementing the light in your greenhouse is necessary to account for daily and seasonal changes to the sunlight hitting your plants, the right supplemental greenhouse lighting can make all the difference when it comes to uninterrupted, high-quality crop production. Greenbelt Microgreens experienced “an immediate 13% increase in yield” with Heliospectra LEDs, according to their Head Grower, Alice Farris, while keeping “production cycles similar from summer to winter.”

Want to learn more about using supplemental lighting to improve your crops and increase year-round production?

The content & opinions in this article are the author’s and do not necessarily represent the views of AgriTechTomorrow

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