In years gone past the ultimate lighting for vertical farming including microgreens used to be 6400k T5 High-Output fluorescents. The small form factor and desirable light spectrum worked great for growing on shelves.
But technological innovation is bringing us new ways to grow. Watch a few different YouTube growers and check out some local operations and you’ll see LED’s are growing in popularity.
The best lighting for growing microgreens indoors are 5000k LED Lights. These lights are energy efficient, have a great color temperature, and are cost effective.
If you’re looking for a quick recommendation: get the Barrina LED Grow Lights in 5000K: they fit perfectly on wire mesh shelves, last forever, have worked for me for over 20 microgreens varieties, and all at an incredible price.
While fluorescent lights can work, they’re falling out of fashion for the following reasons.
- Toxic coatings and ingredients including mercury
- Breakable glass that can contaminate grows
- Less energy efficiency than LED’s
- Low Life & Burn-out: they reduce in brightness over time
Workable alternatives for microgreens lighting include:
- Fluorescent Lights (regular and wide spectrum)
- Panel LED Lights
- Drop in replacement bulbs for common bulb sockets
There are many pros and cons that come with these lighting types, but in the remainder of this article, we will further break down which works best for most microgreens. Of course, budget is a major factor and something you will want to take into consideration when deciding on lighting for your plants. You also want to think about your own personal growing space, the types of microgreens you have planted, and your accessibility to supplies.
Microgreen Lighting Basics
Whether you are just starting out growing your own microgreens or have not had much success in the past, a major issue many gardeners face with raising a healthy crop of microgreens is the lighting. Therefore, before we jump into the different types of lighting available for microgreens, let’s discuss the reasons why your plants have the specific lighting needs they do.
Microgreens have a specific sequence of lighting that is needed to achieve optimal growth, requiring a dark period before exposure to light. Once the right lighting is in place, they tend to be very easy and convenient to grow. Whether you want to keep them indoors or outdoors or use natural light or artificial light—or a combination of both—these plants are at their best in the right conditions.
Why Should You Keep Microgreens in the Dark?
Many do not realize the importance of this dark period for their microgreens, but it is actually vital to their growth. You will want to cover your microgreens and keep them in the dark for the first few days to ensure that they grow into long and beautiful seedlings. The darkness simulates being under the soil, and helps promote more even germination.
It’s also a great way to trap moisture and keep your seeds evenly hydrated while they germinate. A great method is to put another 10″ x 20″ tray on top if that’s what you’re growing in. They’re usually black so they block out light, and they’re plastic so they hold in moisture.
Another benefit is that in the dark, your microgreens are forced to stretch out and search for a light source.
This stretching of the microgreens will help you to have a longer and more tender plant upon harvest. However, your microgreens only have a certain level of starch content in the seed endosperm. This means that they will fall over if they do not get additional energy once this beginning supply is used. This is why it is only recommended for the plants to be in the dark for no longer than three to five days after germination and no longer.
Once you open the plants’ lid and begin exposing them to light, they will be able to complete photosynthesis. This will allow them to become thicker and begin growing healthily for harvest.
Exposing Your Microgreens to Light
When you first allow your microgreens to access light (two to five days after starting the blackout period), they will be pale and probably yellowish in hue. You will want to do your research on the microgreens you are growing for the specifics on blackout timing. Some seedlings will need a longer time in the dark while some do fine with less time.
It is vital that you keep an eye on the plants to make sure they’re growing well, and there aren’t any major mold issues, but do not expect them to be beautiful during this dark period. And don’t worry, once you give the seedlings some light exposure, they will turn green very quickly. At this time, glucose will begin being produced, and the plants will become thicker.
We will jump into the light options that are available, but some other things to keep in mind once the microgreens are at the point of needing light are:
- They will have to be given more water at this point; they will need watering daily to reach proper growth.
- You will want to ensure they are receiving proper air ventilation to avoid any molding problems, a common issue amongst microgreens.
How Much Light Do Microgreens Need?
A major problem that many have when it comes to offering light to their microgreens is that they try to give them light constantly. If your microgreens were growing naturally outdoors, they would not have constant light. When it comes to your plants, they benefits from some time to rest with little or no light, just as they would at night.
Giving your plants a “night” isn’t strictly necessary, I’ve grown with 24 hours of light, but in some cases it makes sense to use a timer.
If you are opting for natural or sunlight as your main source of lighting, then you will not have to worry about this. Essentially, nature will do the work for you, and when the sun goes down, your plants will have a rest period. However, if you are lighting your microgreens with artificial light, you will want to turn them off for a rest period each day.
Ideally, your plants will need at least six to ten hours of exposure to shaded or filtered sunlight each day. For artificial indoor lighting, you will want to provide between 12 and 18 hours of lighting. Some growers do offer 24-hour light and have no issues, but you will want to pay attention to any signs of the foliage curling up.
How Far Should the Light Source be From Microgreens?
When setting up your light source, there are some things you should keep in mind. We will jump into the different types of lighting that will work best, but the distance from your plants is also very important. There is not necessarily a way to over light your plants, but you should keep an eye on any damage that may be caused by your lighting.
The weaker your light source, the closer that you will want to place the plants. If you have a large amount of adequate lighting, you will be able to place your microgreens about a foot away from the plants themselves. If you have natural lighting in the room that you would like to utilize, you will need less supplemental lighting, and it can be at a further distance.
The biggest problem that comes with having close lighting is that the heat produced can damage the plants. If you notice any spots or excessive wilting of the plants and cannot figure out the source, it could be due because of excessive heat. At this point, you will want to move the plants further from the lighting.
Light Terminology to Keep in Mind
Finally, to make understanding the lighting available for microgreens easier, it is important that you know the correct terminology. This will also help make purchasing your lighting options simpler. You never want to purchase a light believing it will work well for you, only for it to arrive as something you did not expect. Some basic light terminology to remember is:
- T5, T8, or T12 – These refer to the tubular diameter of the light tube. For example, the T8 fluorescent lamps are the most used today and are 48 inches long with a 1-inch diameter.
- Lumens – How bright a light will appear to the human eye, but this does not always equate to how well the light will grow plants. The strength of the light is measured by the wattage, the higher the wattage, the more intense the light.
- Kelvins – This is a measurement of the color temperature of the light. Fluorescent tube lights have a temperature from 4000K to 6500K, while LED lighting tubes are available in a wide range of color temperatures. Daylight is around 6500K, and ideal plant lighting should be around this.
- Nm – This refers to wavelengths, which plats will need a visible region of from 400 to 700 Nm.
Natural Light Versus Artificial Lighting for Microgreens
Now that we have the basics out of the way, we will jump into that crucial lighting that your microgreens need. There are a few key things you will want to keep in mind, like the space in which you are growing your plants and your overall available space. If you can grow your plants near a natural light source, finding your lighting is already extremely simple.
Using Sunlight for Your Plants
It is not hard to recognize that sunlight is the easiest—and cheapest—way to grow your microgreens. Also, sunlight is naturally giving your plants a full spectrum of growing light. Most importantly, it is completely free!
There are some important things to keep in mind when it comes to using sunlight and ensuring your plants are properly lighted. Sunlight is natural and free, offering you an environmentally friendly option for lighting your plants. However, you will want to ensure that you are providing enough of this natural light. The things to keep in mind are:
- If you have a window that lets in direct sunlight for at least one-half of the day, it will work for your plants. You can either place them directly into the windowsill, or if you do not have space, you can build a shelf in front of your window to house your plants.
- Sunlight, especially direct light, is the ideal choice for your microgreens. However, light filtered through glass will still offer enough of the ultraviolet spectrum for the microgreens to flourish.
- Often, a single-paned window can emulate a magnifying glass and can quickly warm your plants up; this can be good for microgreens during cooler weather. However, this can also cause the microgreens to somewhat “bake” if they do not have proper ventilation.
- When growing outdoors, exposing the seedlings to a very hot and direct summer sun can also be a problem due to excess heat. However, if you provide enough moisture and windward shelter, this does not affect the plants.
- Indirect sunlight can be just as effective as direct light, as long as you are offering enough time in the sun.
- Some signs of insufficient light you can observe in microgreens are lowered height, no strength, and a lessened color. Some signs of heat exhaustion are discoloration on leaves like sunspots and wilt.
- Finally, plants can handle much more sun and heat than the average human. Do not use yourself as a gauge for their strength!
Types of Artificial Lighting for Microgreens
But, not everyone has a window that is always readily available for plants. Also, if you would like to grow a large number of microgreens, it may not be practical to have all these plants stacked near your window. Luckily, there are several ways that you can light your microgreens without natural sunlight, and many of these options are relatively inexpensive.
The important thing when it comes to lighting for your plants is that you provide a full spectrum of light. Certain plants thrive on different lights, which we will further break down. However, some cheaper options do not offer a spectrum that allows for good growth in the plants.
The most common available lighting options that you will have to choose from when it comes to your plants are:
- Incandescent Lights
- Fluorescent Lights
- LED Lights
- Grow Lights
Within these categories, there are regular (non-labeled) and full-spectrum lights. Grow lights can be further broken down to red bloom and white sun lights.
There are not many in the world today who still use traditional incandescent lights. In fact, most have switched to LED lighting throughout their home. However, incandescent lights are still available, and it is an important lighting option to mention just in case. The major issue that many have with these lights is that they use too much energy, put out a large amount of heat, burn out relatively quickly, and their wavelength is not ideal for plant growth.
If you are unfamiliar with incandescent light bulbs, these are the common bulbs that use a wire filament. This filament is heated up by an electric current, which produces the light effect. Most of the light spectrum emitted from these bulbs is on the infrared and ultraviolet side of the spectrum.
In all honesty, these bulbs are often not the best choice for your plants. However, to make your choice simpler, we will make a quick list of the key things to keep in mind when it comes to incandescent lighting:
- They often produce more heat than light, making them less cost-effective for their price.
- They are the cheapest bulbs to purchase outright. However, they cost more in electricity to operate than other options.
- Often, they do not last longer than three months. On average, these bulbs will supply you with between 1,200 and 2,000 hours of light.
- To make these bulbs work properly, you must put the microgreens close to the bulbs. However, this leads to increased heat and can burn the plants.
This is another relatively inexpensive option that is also widely available to most growers. Fluorescent light is a common choice of lighting because it can be efficient, lower in cost, lower in heat production, and offer a better light intensity. Comparative to the incandescent options we have previously mentioned, these lights last much longer. You can expect to get between 9,000 and 20,000 hours of quality lighting from these bulbs.
Some growers who have been harvesting microgreens for years will swear by using fluorescent lights. They are a great mid-range option that should provide you with adequate lighting. However, some negatives you will want to keep in mind are:
- These lights emit low infrared and ultraviolet light; this can cause fatigue, color pigment fading, and more.
- They are made using mercury, and if the fragile tube is broken, this can be very dangerous; the mercury is highly toxic to humans and the environment.
- They can lose their brightness, and the ballast that powers the light can cause some interference with your electrical devices.
You will quickly notice that LED lights are the lights that work the best for microgreens and are an amazing choice for most growers. LED lights are the future, and many homeowners are making the switch to these light choices.
Over the past few years, the quality of LED bulbs has increased drastically, and the costs of these bulbs have dropped significantly. These bulbs are going to continue to get better each year, and this is a great option for most growers.
LED lighting is a little unique on how that they work, and unless you are well versed in electricity, you may not fully understand the process. The easiest way to explain it is that LED lights use leads as the semiconductor for electric current to pass through. This process allows the release of photons in the form of light.
LED is the newest technology out of the options we have listed thus far. The lights offer better intensity, a lower cost, very little heat, longer lifespan, higher efficiency, and are mercury-free. The initial price for your bulbs may be slightly higher, but they pay off due to the many benefits.
Some benefits of choosing LED lighting for microgreen growth are:
- They come easy to use: simply plug them in, and they work.
- They are lightweight, making them easy to mount.
- They do not produce a large excess of heat.
- They use less energy.
- They cause less electrical interference.
- They do not break and are not made of glass.
- Prices are higher than other lighting options but are steadily dropping.
- They use fewer heavy metals.
- They last between 40,000 and 50,000 hours.
However, there are some disadvantages that come with these bulbs that you do want to recognize. One major issue many have is that they produce a specific range of wavelengths. This means that they may not always provide your microgreens with the lighting they need to grow properly; therefore, purchasing the correct LED light is key.
Which LED Lights Are Best for Microgreens?
The essential requirements for LED lights to work properly for your microgreens are that they have as much wattage as possible and a light temperature of at least 4,000k or preferably higher at 5,000 to 6,500k. The light temperature of K is for Kelvin; this is the light temperature or color. The higher the number, the closer the lights are to natural sunlight.
If you are unsure of which LED bulbs are best, you may want to experiment with a variety of temperature options. You will notice that the higher the K value, the brighter or more natural the light color will be. Often, you will find that most LED lights produce highly similar microgreen results, but it may take some time to find the perfect choice for your plants.
Can You Update Old Fluorescent Bulbs?
If you have a shop light that uses fluorescent bulbs, this may still be useful for LED lighting options. You can make a few basic modifications to these shop lights to make them work for LED bulbs. There are a few websites out that sell replacement bulbs, and you can find videos online that show you how to remove the ballast and easily rewire the light fixture.
LED Grow Lights
Our last and similar lighting option is the LED grow light, but keep in mind it is not the best choice out there. Unfortunately, they are marketed as one of the best options for microgreen growth, but this is not the case. These lights are made by combining many small LEDs in one; this produces a wider wavelength for microgreens.
The problem is that many microgreen growers do not see good results with these LED grow lights. This is because the LED lights used are producing a higher level of red light. Often, experts suggest a bluer light option for microgreens. This is drastically limited with grow lights and does not allow for proper growth.
These lights are also the most expensive of our available options, and this can be disheartening for most average growers. Some things to keep in mind when it comes to these grow lights are:
- LED grow lights are a natural fit for producing many crops. They have low heat emissions, which allow them to be placed close to the crops without any damage.
- They allow for growers to maximize vertical growing space.
- Some grow lights offer adjustable spectrum LEDs, which can be hugely beneficial. These light options will allow the grower to adjust the LED to fit their specific crop.
- LED grow lights are extremely expensive as is, but these adjustable lights are even more expensive. This can be out of budget for most average growers. However, if you are hoping to harvest many microgreens, this may be an option you will want to look into.
How Do Different Light Spectrums Affect the Microgreens?
You may have noticed how often the different wavelengths from each light has been mentioned and how this can lead to quality microgreens. This can be somewhat confusing, especially when you get down to which lights affect each type of microgreen. In general, microgreen growth is best promoted with balanced ratios of red light, while higher ratios of blue light can promote higher nutrient levels.
This can be a lot to digest as a new grower, and it can be difficult to keep up with what types of light your plants need. However, you can do some experimentation with your plants to see what your microgreens like and what helps them grow. It is important that if you offer various lighting options for your plants, you will want to keep notes on what works well and what may not work for your favorite microgreens.
Some growers use light treatments throughout the crop cycle, and others use crop treatments at the end of the cycle. This is a little more advanced, but if you fall in love with microgreen growing, you may soon find yourself learning more about light treatments and how you can offer your plants the best. Some things to keep in mind when it comes to your plants and the way they are influenced by light include:
- Far-red light waves improve the yield and are for blooming and fruiting plants.
- Red and blue lights promote fast growth in plants.
- Green lights enhance the chlorophyll production in plants.
- Yellow lights observe a slower growth rate on average.
- Blue and violet lights enhance color. These lights can also influence the overall taste and aroma.
- Ultraviolet lights can slow down growth and damage the plant.
Finding the Perfect Light
While there are several options of lights that you can use for your microgreen growth, LED or high-output, wide spectrum fluorescent lights are often the best choice. However, you will want to take into consideration your budget and what you want to spend on your lighting. If you are using mainly natural sunlight, you may want to opt for less expensive fluorescent lighting, should there be a cloudy day.
However, if you are going to rely heavily on artificial lighting, LED or 6400k fluorescent bulbs are the best choice. They can be purchased for relatively inexpensive and work well. You can also find these lights at most retailers and a variety of options online, making them easy to add to your grow space. One thing you will want to keep in mind is that any light you choose should be monitored, and you should make changes as needed for your plants.
Thank you for reading this article. I hope you found it helpful as you nurture your microgreens and bring more living foods into your life. Here are some microgreens lighting products I thought might come in handy for you too. These are affiliate links, so if you decide to use any of them I’ll earn a commission at no cost to you. Think of it as buying me a cup of coffee!
I’m Alex Lafreniere. I learned a lot about plants when I built and operated a landscaping company. I learned even more when I started growing and selling Microgreens. But, learning is a journey, not a goal. Ever since travelling across the world, I’ve wanted to find ways to bring more delicious and exotic plants into my life. This is the site where I share everything I’ve learned with you. And maybe we’ll learn a thing or two together.
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