Do Microgreens Need Direct Sunlight?


Microgreens are the seedlings of edible plants often used to add flavor and color meals. The word ‘microgreen’ is not synonymous with just one plant; instead, it describes common microgreens, including cabbage, mustard, beet leaves, celery, and radishes. 

Do microgreens need direct sunlight? No. Microgreens, like all plants, require light to grow. However, that light can come from an indirect light or artificial light sources.

Read on to find more about growing microgreens in sunlight and other alternatives for those cloudy, dark winter days. 

Will Microgreens Grow Well in Direct Sunlight?

Like all plants, microgreens require light, and the sun is a source of which we can all take advantage. Microgreens can grow and thrive in direct sunlight so long as they do not get too hot or dehydrated. Keeping your microgreens inside and behind a glass window will keep them from getting too cold and save them from possibly harmful ultraviolet rays.

Growing microgreens outdoors in direct sunlight is another matter altogether. While microgreens can be grown outdoors, the sun can cause them to bake if proper care is not taken.

Even indoors, the amount of direct sunlight microgreens receive must be closely monitored. Six to eight hours is sufficient. If grown outdoors, microgreens are better off in indirect sunlight, such as in the shade of a porch or tree.  

Direct Versus Indirect Sunlight

Direct sunlight is when the sun’s rays shine directly on your skin or on your microgreens. Left unfiltered, your plants are left to deal with the full spectrum of light and heat from the sun. 

Indirect sunlight is light experienced while under shade and out of direct contact with the sun’s rays. Microgreens grown outside do much better with indirect sunlight.

Ultraviolet Radiation

Depending on the type of microgreens you are growing, ultraviolet (UV) light will improve antioxidant properties in your plants. Often UV light will also strengthen your plant’s ability to fend off diseases and make them stronger. 

However, ultraviolet light has a dark side. Ultraviolet light, also known as ultraviolet radiation, is what contributes to the formation of skin cancer. Just like your skin, it will wilt and burn plants if they are not hardy enough withstand it. Like your skin, microgreens are tender when it comes to what type of light and how much of it that it needs.

Too much light or too little light and the plants die. Microgreens can handle direct sunlight and its ultraviolet radiation for a few hours. However, they must be kept in an area with good air circulation and are well-hydrated.    

How Much Direct Sunlight Do My Microgreens Need? 

Microgreens require 4 to 8 hours of light per day, and it can be direct sunlight as long as you are careful. Direct sunlight will bake your plants if you do not keep them in a well-ventilated area. One can blow air across your microgreens with a fan to help keep them cool, and this will lengthen the time you can keep them directly in sunlight.

Observe the leaves of your microgreens to measure how much your plants are enjoying the sunlight. If they appear to be wilting or curling, it is time to move them into the shade.

Other signs of overexposure to direct sunlight are sunburn-like discolorations on the leaves. These discolorations look like the sunspots one might observe on an elderly person’s face. An excellent way to gauge if it is too hot for your microgreens is to notice how you feel in the sun. If it is uncomfortable for you, it is also uncomfortable and potentially deadly to your microgreens. 

Growing Microgreens Only in In Direct Sunlight

In the first stages of life, when microgreens are only seeds, they need no light at all. They will grow well under cover of a tarp or other covering. It is only after they have germinated that they require the covering removed, and lighting them becomes a consideration. 

Growing microgreens in direct sunlight, such as on a windowsill, works well. This is especially true if the window faces south where the most extended exposure to direct sunlight happens all year round. 

However, there is even danger in placing your microgreens in a south-facing window as they can become quite hot. Check on your plants every few hours during the day to make sure they are not getting too warm.

Direct Sunlight Substitutions for Growing Microgreens

While direct or indirect sunlight is best, using artificial light to simulate sunlight is often needed with indoor farming. This is especially true in darker climates.

You do not need to run out and buy expensive lighting for your microgreens. Everyday fluorescent reading lamps used to read are sufficient to grow a great crop of microgreens.  

However, if you wish to, there are many options out there for artificial lighting. Thanks to the increasing marijuana market, there have been many innovations in lighting technology. These advances, such as digital ballasts that moderate wattage, offer less bulk, less weight, less electricity, and put off less heat.

Artificial Lighting Options

Some artificialOpens in a new tab. lighting, though fancy, can have adverse consequences for growing microgreens. Obsolescent incandescent bulbs generate a lot of heat and light and can become uncomfortable for your microgreens quickly.

As mentioned above, fluorescent bulbs are a cheap substitute for all the unnecessarily expensive equipment on the market to grow plants.

Compact fluorescent bulbs also can become much too hot, with the light being too focused for microgreens to tolerate. Fluorescent tubes emit a greater amount of light than heat and, while not ideal, offer the best lighting for amateur microgreen growers. Compact fluorescent bulbs are available at most flower shops and in large chain department stores at a minimal cost compared to other lighting options.

High-pressure sodium lights, otherwise known as HPS, are another option to think about. They are most commonly used in a commercial setting, due to HPS being a trusted method for quite some time. Keep in mind that these lights will take quite a bit out of your pockets to get started, which is why first-time or early growers do not typically go this route. 

The Cost Differences Between Direct Sunlight and Artificial Light 

Direct sunlight is not needed to grow microgreens as there are other alternatives, including growing in indirect sunlight and artificial light. Both direct and indirect sunlight is free and natural, and utilizing them will save an enormousamount on electrical bills.

Artificial lights used to grow plants can cost a homeowner quite a bit of money, depending on how much your electric company charges. For some homeowners who are trying to save or are conscious of their carbon footprint, they shy away from artificial light.

One method to use direct sunlight without the cost of artificial light is to grow your microgreens in a greenhouse. Building or buying a greenhouse will cost from $5,000-$8,000 depending on how fancy you wish to go. If you are growing microgreens for your own use, only a small footprint is needed. Building a little greenhouse using materials available at any hardware store will do the trick.   However, if you are building one commercially, then the costs on every front will be higher.

With some precautions and an eye out for trouble, you can grow your own microgreens in direct sunlight at home. The increase in nutrition makes growing microgreens a popular and hardy addition to any meal. The cost of growing microgreens in either direct or indirect sunlight is negligible as sunlight is free. 

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