The Role of Grow Lights in Greenhouses

Effective lighting is a key component of modern greenhouse farming. By utilising the right grow lights, growers can optimise conditions for photosynthesis, significantly enhance plant growth, and ultimately increase crop quality and yield all year round. 

Let’s explore the science and technology behind grow lights. The more you understand this invaluable tool, the better-informed choices you can make for your greenhouse operation.

Lumen vs. PAR

While lumens measure the brightness of light perceived by the human eye, PAR quantifies the amount of usable light for plant growth, measured in micromoles per second (µmol/s). Understanding this distinction is key when selecting grow lights, because then we’ll know to focus on PAR, not lumens, to ensure our crops can photosynthesise effectively.

Choosing the right grow lights for your greenhouse

All grow lights convert electrical energy into light (and heat), but selecting the right grow light involves several considerations:

Light output: Higher output lights can drive greater photosynthetic activity

Light spectrum: Different crops and different stages of plant growth require different light spectra.

Power consumption: Energy-efficient lights reduce operational costs while maintaining high output.

Efficacy: High PAR efficacy ensures that the electrical energy consumed is effectively converted into usable plant light.

There are also several types of grow lights available, each with specific characteristics and benefits:

Metal Halide (MH) lamps are known for supporting the growth of young seedlings by providing a light spectrum that enhances the development of strong, healthy plants.

Ceramic Metal Halide (CMH) lamps offer a broader spectrum, similar to natural sunlight, which is beneficial throughout the plant’s growth cycle.

High-Pressure Sodium (HPS) lamps are favoured during the flowering stage due to their emission of red spectral wavelengths, promoting flowering and fruiting.

Light Emitting Diodes (LEDs) provide a customisable spectrum and are more energy-efficient, allowing for precise control over light intensity and spectrum based on a crop’s specific needs.

Setting up your grow lights

So you know you need grow lights, and even which ones you want to install, but there are more questions about your particular greenhouse setup that you need to consider. 

• How will lighting affect other operations? Some operations, such as climate control and irrigation strategies, must be adjusted accordingly.
• What is the current requirement for the grow lights, and how does it affect the sizing of cables and electrical installations? Lights have a high energy demand and the requirements for this must not be overlooked.
• How many light fixtures do you need to achieve an ideal light level, and what height should the fixtures be mounted to optimise light distribution and minimise shadowing?
• How will the grow lights be controlled? Can they be dimmed or adjusted to meet different growth stages?
• What is the expected lifespan of these grow lights? What maintenance do they require to remain effective and efficient?
• Beyond examining product datasheets, have you considered obtaining a light simulation model to see how the lights perform in an actual use-case scenario? This can help identify if there are any discrepancies between the product’s specifications and its real-world performance.

Want to grow at the speed of light?

Understanding the intricacies of grow lights can be a daunting task, given their technical specifications and the critical role they play in greenhouses. At Vegtech Netafim, we are committed to demystifying this essential technology and creating more productive and sustainable farming practices for all.

Reach out to us today at +27 21 987 6980 or info@vegtech.co.za to learn more about how our grow light solutions can illuminate the path to your agricultural success.