LED Arrays Prove to be Excellent Match for Horticultural Lighting

plants under LED grow lights

Today we live in a world where much of the food we eat is not dependent on the growing season where we live. Rapid global delivery systems have allowed grocery stores to stock virtually any type of fresh fruit or vegetable any month of the year.  The tomato you buy in August may come from a local farm. The tomato you buy in January may come from Mexico.  Increasingly, that tomato may also come from commercial greenhouse operations in the U.S. that harvest produce year around.

Large scale greenhouse production shows year over year increases and total greenhouse square footage capacity keeps growing. The increases in the U.S. reflect a worldwide growth in the greenhouse industry.

These trends translate into higher demand for horticultural lighting products at a time when the lighting industry itself is undergoing dramatic changes with the maturation of the LED market.

Traditional Grow Lights Use HPS or Metal Halide Lamps

Historically, commercial hydroponic and greenhouse operations have used fixtures with high pressure sodium, HPS bulbs or metal halide bulbs. These light sources offer the red and blue spectral output required for foliage growth and flowering. However, the energy requirements, 400 watts to 1000 watts per bulb, are so high that in some cases large greenhouse operations must notify the utility company of their lighting schedule. One can only imagine what the monthly electric bill looks like in seasons when these lights are on 16 hours a day, 7 days a week!

Because of significant light output capability, relatively long bulb life and reasonable bulb costs, HPS has been the dominant horticultural light source for years, in spite of the energy drawbacks. There have been no alternatives until now.

LED Allows Precise Spectral Tuning For Optimal Plant Growth

In the last year or so, LED lighting has become a legitimate, even powerful alternative to traditional grow lights.

Because solid state LED arrays can be tuned to precise spectral wavelengths, it is possible for a single LED fixture to emit both red and blue radiation to match the photosynthetic requirements of the plants. Traditionally this may have required switching light sources between HPS and metal halide to achieve optimized red or blue light depending on where the plants were in the growth cycle.

Of even more significance for the grower is the difference in energy requirements between HPS and metal halide compared to LED. A 325 watt LED fixture can provide at least the same light output as a 1000 watt HPS fixture. With one third the energy costs and five times the rated LED array life, LED fixtures usually show a return on investment in less than three years.

Sylvania ZELION HL LED Fixture Enters Grow Light Market

One example of an LED fixture designed specifically for horticulture is the just released Osram Sylvania ZELION HL LED grow light.

According to Sylvania , “LED lighting can stimulate plant growth by up to 40 percent.” Using LEDs from Osram Opto Semiconductors, the ZELION HL targets lighting wavelengths at 650 and 450 nanometers. This unique optical design delivers optimal PAR (Photosynthetically Active Radiation) to the plants.

In addition to precise horticultural light tuning, “The features of LEDs for horticultural lighting, such as small form factor, high efficiency and long life, provide flexibility and cost effectiveness for growers,” according to Sylvania,

LEDs can also be controlled more easily than HPS or metal halide. With instant on and the ability to program cycles that promote healthy plant growth, LED fixtures offer benefits generally not available with HID fixtures.

ZELION HL LED fixtures are available in 25W, 50W, 100W and 150W versions designed to replace 255W to 1000W HPS fixtures.

With these products, Sylvania has jumped into the LED horticultural market. Others will follow as the demand expands for year-around greenhouse production and inevitably for LED products that match the specific needs of horticultural lighting while reducing the historically high lighting energy costs for producers.

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Dave Burtner

Dave has been active in the lighting industry since 1994. Formerly a member of the Illuminating Engineering Society of North America and certified by the National Council On Qualifications for Lighting Professionals, Dave now writes blog posts, lighting tips and provides lighting product assistance for the Topbulb website.

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