Essential Factors to Consider in Your Greenhouse Lighting Plan
Using essential lighting quantifications and strategic planning factors will help you choose the right lighting plan for your CEA facility. | Total GrowLights
In my last two articles for CEAg World, I explored how essential lighting quantifications and strategic planning factors drive successful projects. Now it’s time to put these pieces together in a practical planning methodology. The TotalGrow DIY Lighting Calculator walks you through this process systematically, helping you input key parameters to see how different decisions impact your lighting plan firsthand.
1. Define Your Growing Parameters
Start by clearly defining your crop category, growth stage, environment type, and overall lighting goal (maximum impact, minimal cost, or a middle balance) in the calculator. Different crops have dramatically different daily light integral (DLI) requirements — lettuce needs roughly 10-17 mol of light per square meter per day (mol/m2/day), while tomatoes require between 20-50 mol/m²/day.
Your environment fundamentally affects every decision you make. Sole-source indoor operations need higher intensities and uniformity than greenhouse supplemental applications, where sunlight meets much of a plant’s lighting needs.
For example, on one of our recent projects with a greenhouse herb grower, we established that a high (optimum) lighting target fit their business goals for a target DLI of 17 mol/m2/day. Their greenhouse receives ~5 mol/m2/day during their Michigan winters, requiring ~12 mol/m2/day of DLI from LED lights.
2. Calculate Light Requirements
The DIY lighting calculator translates your goals into specific targets. Input your target DLI, subtract available natural light, and choose your photoperiod to determine the required photosynthetic photon flux density (PPFD).
For the greenhouse herbs project, the lights can run for up to 18 hours per day. Providing 190 µmol/m2/s PPFD light intensities for 18 hours accumulates to the 12 mol/m2/day DLI needed to meet their growth goals.
3. Factor in Strategic Constraints
Input your strategic constraints — physical space dimensions, mounting height, and budget priorities. Available height determines fixture selection — more height allows fewer, more powerful lights, while limited height requires more fixtures for uniform distribution.
Budget considerations balance initial costs against operational efficiency. Seasonal operations often benefit from lower-cost, standard-efficacy fixtures, while year-round facilities can consider higher-efficacy options.
The herbs greenhouse we worked with had relatively low available heights at six feet from crop to fixture, requiring lights to be a maximum of 12 feet apart to maintain uniformity. However, they had a relatively high target intensity, which requires a higher concentration of light fixtures than the 12-foot maximum spacing. They also had the added benefit of a utility incentive and financing program that made it easier to budget for a top-end lighting intensity in their plan as long as they minimized the upfront cost per watt.
Ultimately, 660-watt, 2.6 micromoles per joule full-spectrum LEDs with 9-foot centers throughout their 18-by-156-foot bays allow them to maintain summertime production quality and yields every month of the year. Light sensors and controllers dim and brighten the lights automatically to maintain the target intensities while minimizing wasted power.
For the final key parameter and additional guidance for optimal lighting results, please read the original article found on our sister site, CEAg World.
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