Microgreens Lighting Setups for Consistent Growth

Lighting can make or break your microgreens production. To achieve consistent growth across every tray - with no weak or yellow patches - you need a well-designed lighting setup. In this article, we'll cover how to choose the best lights (hint: LEDs are the frontrunner), how to arrange them for even coverage, and tips for maintaining light quality. Whether you're upgrading from a basic shop light or setting up a multi-tier rack system, these lighting strategies will help ensure all your microgreens get the illumination they need to thrive.

Why LED Lights Are Preferred

Modern microgreen growers overwhelmingly choose LED grow lights for their operations, and it's easy to see why. LEDs offer several benefits that align perfectly with microgreen cultivation:

• Energy efficiency: Quality LED fixtures produce a lot of light with very little electricity. They consume significantly less power than old-school fluorescent or incandescent bulbs, which lowers your operating cost and heat output. For a commercial or semi-pro grower running lights up to 16 hours a day, the energy savings add up quickly.

• Low heat emission: Unlike high-intensity lamps, LEDs run cool. They emit minimal heat towards your plants. This means you can place LEDs close to the microgreen canopy without risk of burning them or overheating the space. Microgreens generally prefer cooler conditions, so the low heat of LEDs helps keep your environment in the optimum range.

• Customizable spectrum: LED technology allows manufacturers to tailor the light spectrum. Many LED grow lights are "full-spectrum," mimicking natural sunlight, which is great for all-purpose growth. Others emphasize specific wavelengths like blue (to keep seedlings compact) or red (for overall growth). For microgreens, a full-spectrum (or at least a cool-white around 5000K) tends to yield excellent results, promoting green color and healthy form. Some advanced growers experiment with higher blue ratios to prevent any stretching. The key point is, with LEDs you have options; with something like a fluorescent tube, you're stuck with its fixed spectrum.

• Longevity: LEDs last tens of thousands of hours before significant degradation. This means you won't be frequently replacing bulbs. Consistent output over time also means consistent crop performance - you won't suddenly get weaker light as often happened when fluorescent tubes got old. It's one less variable to worry about once your system is dialed in.

• Form factor and flexibility: LEDs come in various shapes - panels, strips, screw-in bulbs - giving flexibility in how you install them. For vertical farming racks, slim LED bars or strips can be mounted under each shelf, a very space-efficient solution. There are also LED panels that cover a larger area if you have a big shelving unit or table. Because they can be arranged easily and even daisy-chained (many units let you connect multiple lights), it's relatively simple to scale your lighting setup or reconfigure it as needed.

In summary, LED grow lights provide strong, efficient, and controllable lighting ideally suited for microgreens. While there is an upfront cost, there are also affordable options on the market (with decent entry-level LED grow lights available in the €20-€50 range, and higher-end commercial ones costing a few hundred each). The investment pays off in plant quality and lower energy bills. Traditional fluorescent lights (like T5 fixtures) can grow microgreens fine, and if you already have them, you can use them - just be mindful of the heat (keep them a bit further away, ~30 cm) and replace bulbs yearly as their output diminishes. But if you're starting fresh or expanding, it's worth going for LEDs for the advantages above.

(For more on the benefits and types of LED lights, see our Advanced Growing Systems Guide where we discuss lighting in a commercial context.)

Positioning Lights for Even Coverage

Having great lights is one thing; using them effectively is another. To get uniform growth, you need to ensure that each part of each tray receives roughly equal light. Uneven lighting can cause some sections of a tray to lag behind (e.g., edges of tray growing slower if light is centered) or plants bending toward the brighter side.

Here's how to achieve even coverage:

• Distance from canopy: As a rule of thumb, position LED lights about 20-30 cm above the microgreen canopy for broad coverage. At this distance, light spreads out to cover the tray while still providing good intensity. Some lower-power LEDs might need to be closer (~15 cm) to give enough intensity, but be cautious going much closer than that unless you're sure the light won't cause heat or phototoxicity. If using fluorescent tubes, about 20-25 cm is often used. Keep in mind as microgreens grow (a few centimeters tall), the distance closes a bit - so adjust lights upward if needed to maintain the sweet spot.

• Coverage area and overlap: Each light has a recommended coverage area (often given in specs, like a panel might say it covers a 60×60 cm area at a certain height). Ensure your lights cover your entire tray area. For example, a common 10×20 inch (25×50 cm) microgreen tray - one decent LED panel can cover that, but if you use very narrow strip lights, you might need two side by side to avoid dim edges. It can be helpful to look at the brightness on the tray: you can use a lux meter app on your phone to check different spots. The readings don't need to be exact, but they should be in the same ballpark across the tray. If the center is getting double the lux of the corners, you have a hotspot - consider raising the light a little (to increase spread) or adding reflective material around.

• Reflective surfaces: Surrounding your growing area with reflective or light-colored surfaces helps bounce light to the lower parts and edges. Mylar (the shiny foil-like material in grow tents) or even white-painted walls can improve overall uniformity. If you have a multi-tier rack in an open room, one hack is to hang some reflective sheets or even emergency blankets around the sides of the rack to keep light from escaping sideways. This effectively increases light availability to your plants without adding more fixtures.

• Multiple light sources: In larger setups, using multiple lights from different angles can reduce shadows and ensure uniform light. For instance, two LED bars placed in parallel over a wide shelf will give better uniformity than a single point-source lamp. Overlap their coverage slightly so there are no weak spots. It's akin to lighting a photography studio - multiple lamps reduce harsh shadows. For microgreens, shadows aren't as big of an issue due to their size, but overlapping light fields definitely evens out growth.

• Tray rotation: Despite your best efforts, you might still find slight differences, especially if using window light or one-directional lighting. Rotating trays 180° halfway through the grow cycle can help plants even out. Many small growers do this: after 3-4 days under lights, turn each tray around. This way, what was the far side now becomes the near side to the light, balancing any lean or disparity. In continuous systems, rotating daily or every watering is an option (though in a very optimized setup, this shouldn't be necessary).

• Height adjustments: Different microgreen varieties can vary in height. If you grow tall ones (like peas, which can reach 15+ cm if you let them) alongside tiny ones (like cabbage microgreens, ~5 cm), you may need to compromise on light height or separate these so that shorter crops get a bit closer light. One approach is to group crops by similar expected height under the same light. Most common micros (radish, broccoli, etc.) stay within 5-8 cm, which is manageable uniformly. But if, say, your pea shoots are stretching close to the light while the others are far, consider raising the light a tad for the peas' sake or elevating the shorter trays on a riser to bring them closer.

Setting Up a Multi-Tier Lighting System

If you are using racks with multiple shelves (a typical way to scale up microgreens), you'll need to equip each level with lights. Each shelf effectively becomes its own mini grow area:

• One shelf, one light (or set of lights): Mount LED strip lights or panels to the underside of each shelf so they shine on the tray below. Many vertical farmers use 2-4 LED strip bars per shelf (depending on shelf width) to cover the area. Ensure that the entire shelf area where trays sit is lit. If your shelves are, say, 120 cm wide and your LED bar is 100 cm, position it centrally and you might get away with it. If edges seem dim, use two bars with a small gap between, covering more width.

• Wiring and safety: Manage cords neatly using clips or zip ties along the rack. You might use a single timer for all levels (just plug a multi-outlet strip into a timer, and all lights into that strip). Be mindful of water and electricity - always plug lights into GFCI-protected outlets if possible, and route cords away from where water might drip during watering. Most LED fixtures are fairly water-resistant, but it's best practice to avoid direct splashes on them.

• Adjustability: If possible, design your setup so you can adjust the height of lights as needed. Some racks have chains or hooks that let you raise/lower the lights. Others fix them at the shelf bottom and you adjust tray height if needed by putting spacers under trays. If growing a mix of crops on one shelf, usually you set the light height to accommodate the tallest at maturity so they don't hit the bulbs, and accept that smaller ones get a bit less intensity (again, grouping similar plants per shelf helps).

• Consistent spacing: Make sure each shelf has roughly the same distance from light to tray. That way all tiers get equal light and you can expect uniform results across levels. If the top shelf has 20 cm and bottom shelf has 30 cm distance, the bottom shelf crops may grow a little differently (possibly stretch more). So, measure and try to have a consistent gap.

A well-lit rack system can produce microgreens of comparable quality on every tier - no more "the top shelf always does best" issues. If you notice any shelf doing differently, double-check that shelf's light intensity vs the others (sometimes slight differences in fixture or height can do that).

Avoiding Common Lighting Mistakes

A few pitfalls to watch out for:

• Inadequate light duration: As mentioned earlier, aim for that 12-16 hour range of lighting daily. Don't under-light them thinking ambient room light will suffice - it usually won't. If microgreens don't get enough total light, they end up thin and less flavorful. Use a timer to ensure they get a full photoperiod every day without fail. Consistency is key; erratic lighting (on one day, off the next) will confuse the plants and lead to inconsistency.

• Light too far away: We've touched on this, but it's worth reiterating - if lights are too far, plants stretch. Leggy microgreens are weaker and often more prone to flop over or have a lower shelf life. Keep those lights close enough to encourage stocky growth. You'll know you hit the mark when microgreens grow sturdy, with the cotyledons (seed leaves) broad and flat, not reaching upward excessively.

• Not accounting for bulb degradation: If you're using any non-LED lights, remember they dim over time. A fluorescent tube loses a significant percentage of output after 6-12 months of use. If you suddenly see poorer growth and nothing else changed, consider the age of your lights. With LEDs, degradation is much slower, but very cheap LEDs can also dim after a couple years. Keep an eye on performance and be ready to replace lights when needed to maintain results.

• Uneven light color: If mixing different types of lights, say sunlight plus an LED, be aware plants might respond by bending toward one. Ideally use uniform lighting types in one area. Mixing warm and cool lights is generally okay (plants will take all the spectrum they get), but physically having two opposite sources can cause minor leaning. Usually though, as long as intensity is sufficient, microgreens will just grow straight up.

• Ignoring heating from lights: Though LEDs run cooler, they still generate some heat upwards (the drivers and diodes get warm). In a small enclosed space, lights can raise the temperature a few degrees. Check your environment after lights have been on for a while. If it's creeping above your ideal temp, add an exhaust fan or slightly open the area to dissipate heat. Luckily microgreens tolerate a range, but you don't want a big temperature spike from noon to evening. This is especially a warning if anyone tries HID or other high-intensity lights (rare for microgreens because overkill) - those could cook your crop if too close.

To truly ensure consistent growth, combine good lighting with the other environmental controls: stable temperature and adequate humidity/airflow (see our environment control guide for more on those factors). Lighting is arguably the most important, as without enough light, even perfect watering and nutrients won't save a crop from floppiness.

In conclusion, investing in a proper lighting setup is essential for uniform microgreens production. By choosing efficient LEDs, positioning them wisely, and monitoring your plant's response, you'll eliminate lighting as a source of variability. The reward is microgreens that look and grow equally well in every corner of every tray - a consistency that both you and your customers will appreciate.

Soft CTA: Ready to see your microgreens in the best light? Pair your optimized lighting setup with top-notch seeds from Deliseeds to ensure uniform germination and growth. With great seeds and great lights, you're on the way to a flawless crop!