Ask the Experts: Lighting

During my time in the horticultural industry, I’ve run across the same question a hundred times over — why should I use supplemental lighting and what are the potential benefits? The best one-line answer that I’ve been able to come up with is, “What grows better: plants that are in direct sunlight or plants in the shade.” Supplemental lighting systems allow growers to make every day a sunny, productive day.

Below is a general breakdown of the key benefits for lighting, broken up by five different crop styles.
 

• Potted plants — These respond very well to supplemental lighting. Potting plants will typically increase in overall size up to 30 percent depending on growing conditions. The number of flowers per plant will also increase with a more distinct and vibrant color on the individual flowers. Scheduling is something that will also be affected by the use of growing lights. Plants under lights tend to have more constant, predictable and shorter growing periods. Ultimately, the plants will mature in a shorter period of time and be stronger, bigger, healthier and more resistant to disease.
   
• Bedding plants — With bedding plants, supplemental lighting will give growers the ability to move up flowering so that your crop is one of the first to market and also potentially allow growers to squeeze in another planting. The plants are usually up to 20 percent bigger, firmer and grow more vigorously than similar plants grown at lower lighting levels.
   
• Stock Plants — Mother Plants that are grown under supplemental lighting often yield a 25 percent increase in the number of usable shoots. These shoots are typically much stronger and healthier than similar plants grown without horticultural lights. These cuttings also have the ability to root faster and are considerably more resistant to disease/pests.
   
• Cut Flowers — These types of plants respond very well to the addition of grow lights and, depending on the growing conditions, yield an extra 50 percent more usable stems. These shoots grown under the higher light levels are typically much stronger and resistant to damage during harvesting and packaging. The flowers have enhanced color and often produce larger blooms than their low-light equivalents. The addition of grow lights also allows greenhouses to grow summer varieties during the winter months, which can demand higher prices. Flower production becomes much more streamlined allowing for more consistent growth with the need for less labor and more predictable and uniformed growth.
   
• Vegetables — The main reason for using supplemental lighting with vegetable crops is that it allows the end-user the ability to grow their product year-round. Production can be maintained during the off peak months where the prices are highest. Lighting of vegetable crops will provide an increase in kg/m2 making for more productive use of their growing space. Growers often report a decrease in the number of aborted flowers while the harvested fruits tend to be larger and better tasting.

As you can see, the benefits of supplemental lighting are pretty amazing. For almost every type of plant grown within a greenhouse, supplemental lighting will help to produce stronger, healthier product that will help to set your greenhouse operation or brand apart from the competition. The real question is can you afford not to light?

Jon Adams is a sales engineer for P.L. Light Systems.