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What Lights Do I Need to Grow Microgreens?

February 18, 2022 9 min read 0 Comments

Microgreens grown with lights

Microgreen Grow Lights Setup

Microgreens are a great crop for anyone to grow because they are very flexible with their requirements,  including lighting.Because microgreens do well using a variety of light sources, it's easy for the home grower to start where they are and still produce delicious microgreens.

To grow microgreens, you can get by with a few trays by a sunny southern window or go all the way to a full vertical rack system with high-powered LEDs and commercial production.

In order to recommend the right lights for your microgreens grow setup, there are a lot of factors to take into consideration. Are you growing for home use or commercial sales? How many trays are you growing? Do you have access to sunlight, for example, a greenhouse or sunroom? Are you planning to grow year-round? Do you need reliable harvest times or are you more flexible? How much money can you invest in your light system?

Here we will go over the most popular lighting options from lowest to highest in terms of cost and list some of the pros and cons of each.

microgreens

Microgreen Grow Light Options

Sunlight and Natural Light for Growing Microgreens

This is, of course, the cheapest and most complete spectrum light source available. For the home grower, any sunny window sill or small greenhouse can be used to grow microgreens, although with windows you will have more issues with curved stems and slower, leggier growth. Windows can provide enough light to get you by but are really the last resort option for growing.

In larger-scale operations, greenhouses or high tunnels with tables can be used to grow microgreens when limited space is not a concern.In a greenhouse or high tunnel, you don't need additional artificial lighting to grow microgreens well.

Pros: Free, readily available, no wiring or timers needed, complete light spectrum in the 6500k range on a clear day.

Cons: Inconsistent due to seasons and weather, produces heat that can affect growth, does not work well in vertical rack systems, requires supplemental lighting in winter months, can cause leggy microgreens and slow growth in some scenarios.

Fluorescent Shop Lights

Fluorescent shop lights are similar to LEDs in light production but use more power and produce more radiant heat so we don’t recommend them here. They also regularly contain mercury which can contaminate your grow area if the bulbs are broken. If you are using existing fixtures we recommend replacing the CFL bulbs with LED.

LED Bulb Shop Lights

LED bulb shop lights can be purchased at most big box stores for around $20 a piece and they are a standard 4’ long.These make an excellent trial light when you are ready to try growing indoors or expand to a vertical rack and increase growing capacity in a limited footprint.

These LED shop lights work fine for microgreens that have shorter growing cycles but struggle when trying to grow microgreens with longer growing cycles like herbs. These varieties need a higher light spectrum than LED shop lights can provide. If you want to grow these kinds of microgreens, you should go for an alternative type of light system. We have a top ten list of our favorite microgreens to grow here that you can use as a jumping-off point.

Pros: Inexpensive, easy to find, acceptable light spectrum 2200k-4000k for microgreen growth, produces minimal heat, can usually be daisy-chained 3-4 lights, work with 120v household electrical outlets.

Cons:Bulbs are often unprotected from water and dust making them susceptible to damage, brands vary greatly in quality, are normally designed to be installed horizontally only, are less efficient than strip LEDs, generally last far fewer hours than strip lights, light spectrum too low for longer growing crops (this shows as discoloration in the leaves in later stages of growth or plants becoming too leggy and falling over before harvest).

LED Strip Grow Lights (T5)

Strip grow lights like the ones we sell here that are designed for gardening and growing microgreens are available in multiple sizes and intensities. They are often sold in the same standard 4’ as shop lights, but other lengths are available. Full-spectrum strip lights above 5000k run from $75 on the low end through to $650.

Most grow lights offer a standard growing area of 4’x2’.They can come with or without the surrounding reflector that gives it the classic shop light shape, which helps redirect light and therefore increases efficiency.This maximizes the light available and can help increase microgreen yields.

These lights are commonly used in vertical growing systems because they can be installed vertically or horizontally.

Pros:Moderately expensive, can be found in hydroponic stores and online, full light spectrum 4500k and above allows for longer growing periods, produces minimal heat, efficient watt to lumen ratio, the good ones offer lighting surfaces that are protected from dust and water, can usually be daisy-chained up to 7 lights, most work with 120v household electrical outlets, some can be installed vertically if needed for your set up.

Cons:Moderately expensive(pro or con depending on your situation); quality, efficiency, and longevity can vary greatly between brands.

LED Panel Lights for Growing Microgreens

These are the top-of-line growing lights for indoor use and can be used for microgreens as well as all other types of plants.They are generally used in the large-scale commercial growing of plants that need to reach full size or reach the flowering stage indoors.

The high light intensity found in these lights could be considered overkill for growing microgreens. Ranging in price from $99 up to thousands of dollars, they can be very expensive for a small grower. The growing area that these lights cover is typically 3’x3’ for smaller panels up through 8’x8’.

Pros: Come in a variety of sizes, intense full-spectrum light capabilities, variable sizes for customized growing spaces, highly efficient watt to lumen ratio.

Cons:Expensive, thick profile limits their ability to work in vertical rack systems, generally require separate ballasts for electricity, must be purchased from specialty suppliers online or in hydroponics stores if they are available in your area.

microgreens

How far should my lights be from microgreens?

The distance that your lights need to be from your microgreens dif generally between 6-12 inches above your microgreens. However, the type of light source that you use can affect the ideal distance because certain lights produce heat that can burn the microgreens if placed too close.

Most LED strip lights do not generate enough heat to cause problems and do well 6-12 inches from the surface of the growing greens. The farther the greens are from the light source the more they will “stretch” and become leggy.

Panel lights are higher intensity and can be placed farther from the growing surface without too much light loss.

microgreens growing outdoors

How Many Hours of Light Do Microgreens Need?

In general, plants (including microgreens) need at least six hours a day of quality light in order to grow.

If you are using sunlight as your main light source, you are not really able to control the light exposure and intensity. But by being aware of shade patterns and light direction when setting up your system, you can maximize the light available to you.

When growing indoors, it's important to experiment with the light sources available to you so that you can grow your microgreens effectively and easily in a way that works for you. Some growers keep lights on 24/7, others use 12 hours on/12 hours off modified daylight system to grow their microgreens.

You can also do 18 hours on/6 hours off system that provides a balance between pushing for growth and allowing for "rest" time for the plants. Some growers say that this system provides the best color and flavor to develop in the microgreens, so it's important to test the different light exposure times until you find something you're happy with.

What do light spectrums have to do with growing microgreens?

Microgreens normally don't need as high of a light spectrum available to them in order to grow effectively. Light spectrum comes more into play when you're dealing with other types of plants that have longer growing cycles (tomatoes and peppers) or plants that you're trying to push to the flowering stage (chamomile, zinnias, cross-breeding experiments).

However, some types of microgreens do need a higher light spectrum because they take longer to grow. When growing herbs or other plants for micros that have a growing cycle longer than 20 days, you need to upgrade your lights so that they produce a color temperature above 4500k.

Most lights will be labeled between 2000K to 6500k. On the lower end of this scale (color temperatures from 2000K to 3000K) are referred to as “warm white” and range from orange to yellow-white in appearance.

Color temperatures between 3100K and 4500K are referred to as “cool white.” This range will emit a neutral white light.

Above 4500K will give off a blue-white light that mimics daylight and is what you need for any plant with a growing cycle longer than 20 days, including microgreen herbs.

Lumens to Watts is another phrase you will see in a lot of light comparisons. This refers to the amount of light produced per watt of electricity used. LEDs are the most efficient by far for this.

microgreens

What are the best lights for microgreens?

When it comes to lights for growing microgreens, there are a few things to consider. The most important factors are the wattage, lumens, and spectrum of the light. Other specs, such as coverage area and PAR levels, can also be important depending on your setup. There are many factors that go into play to determine which lights are right for you.

LED grow lights are a popular option because they are affordable, energy-efficient, and produce consistent results. They come in a variety of spectrums so you can find one that matches your needs. Additionally, they are energy efficient so they are environmentally friendly and save you money on your electric bill.

How many watts do microgreens need?

Microgreens need a minimum of 20 watts per light. Microgreens thrive with supplemental light, but they don't need as much as other plants. This is because most varieties of microgreens are grown in short cycles of less than 20 days. We provide grow lights that are flexible and can be used for microgreens or any other plants you want to grow.

Microgreens are typically grown in a dark environment for the first few days of their lives. After that, they need to be transferred to an area where they can get at least six hours of sunlight per day.

What's a T8 fluorescent?

A T8 fluorescent light is a type of tubular light that is 8/8 of an inch in diameter (aka one inch) as compared to a T5 light which is 5/8" in diameter. A T8 is larger than a T5 in diameter but longer in length. The lumens and watts of a T8 are typically lower than a T5 light, so while it is more energy-efficient, you end up not being able to reach high enough lumens for most plants to grow.

For microgreens, a T8 fluorescent light would be sufficient if you intended on only growing microgreens with a growing cycle shorter than 20 days. If you grow a longer cycle microgreen or want to use these lights for other plants as well, a T8 will not be the right light for you.

planting microgreens

When should I expose microgreens to light?

Microgreens should grow in darkness (often stacked, as described in this podcast episode) for about 3-5 days after sprouting to ensure higher yields and easier harvesting. Slower-growing microgreens will be on the longer end of this spectrum, while faster-growing microgreens will be on the shorter end.

How do you know your microgreens are getting enough light?

If your microgreens aren't getting enough light, they will stretch out and be weak and thin. Leggy microgreens are a result of not having enough light. When they lack light, the plants stretch out in search of it. This makes them less aesthetically pleasing and also affects the flavor of the greens.

Too much light or light that is placed too close to the plants can also be harmful to microgreens. It can cause them to lose their color and stockiness and can burn the tops.

How many hours a day should your microgreens get light?

Microgreens need at minimum 6 hours of light but do best when put on a schedule of 18 hours on/6 hours off. Some growers prefer an even 12 on/12 off model but we like extending the light period to encourage faster growth.

What is the best color temperature for microgreens?

The best color temperature for microgreens is around 4,000K to 6,500K. This range will provide the plants with enough blue and red light for photosynthesis that results in fast grwoth. Daylight colors have a color temperature between 4,600K and 6,500K, so using fluorescent light bulbs in this range will be ideal.

Microgreens can be grown at a cooler color temperature, but they will have the best color and grow fastest when in this optimal range.

What light intensity do you need for microgreens?

Microgreens need at minimum 20 watts per light and ideally lumens that fall in the daylight spectrum - 4600K-6500K.

The amount of light you need for microgreens depends on the intensity of the light and how close it is to the plants. In our automated grow rack system, we have 4 T5 LED lights at 6500K per shelf.

Can a grow light be too strong?

Grow lights can be too strong if they are placed too close to the plants or are designed for commercial operations and used at home. Some lights are so strong that they can bleach the colors of everything around them, so they are not a good choice for a home grower.

The stronger the grow light, the further away the lights should be from the top of the plants. We recommend going with a T5 as a standard light source that can be used for all plants, including microgreens.

growing microgreens


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