Light It Up: How to Regulate Light to Grow Healthy Microgreens


Microgreens are a miracle. Packed with as much as 40 times the nutrients than their full-grown counterparts, as well as being tasty and colorful additions to your meals, scientists continue to tout their benefits. With so much going for them, there is one drawback: they are expensive. With short growing seasons in much of the country and the fragility of the microgreens themselves, many gardeners have decided to grow them at home. In addition to the lights, the seeds, and the containers, you need to think about the light to grow your microgreens, as it is an integral part of the growing process for microgreens.

Importance of Light in Germination

Although heat is important in germination, light is not. Microgreens grown outside are covered in soil and germinate away from the scorching sun. And if you are growing your microgreen seeds indoors, you can completely cover your microgreen seeds in soil, as well as completely cover the tray with a lid, and they will still germinate. You can even germinate your seeds in a metal cabinet! In fact, a warm dark place is often what seeds crave in order to germinate.

How Light Affects Growth

Once the seeds germinate, the microgreens flourish with sunlight, and this is the best way to get your microgreens to grow. Light is required for photosynthesis, the process by which plants synthesize carbon dioxide to create oxygen. This process also creates chlorophyll, which gives leaves their green color.

Microgreens need at least 10 hours of sunlight a day, complemented by 6 hours of darkness, for proper growth. The more light plants get, the more they will flourish. If they don’t get the recommended amount, they will still grow, but they will grow more slowly and with fewer nutrients produced.

Plants can grow in direct or indirect sunlight. But a problem occurs if plants are in insufficient light. In this case, they grow very tall and skinny in a vain search to find sunlight. The term for this is “legginess” and it causes the stems to be tough and better and fibrous.

If plants are given sufficient sunlight, whether direct or indirect, they thrive and tend to grow wider. Although it seems counterintuitive, there are some plants that grow best in indirect light. These include arugula, mustard greens, dill, and aramanth. If given too much direct sunlight, these plants can wither.

Sunlight vs. Artificial Light

There are two ways to provide your plants with light, and there are pros and cons to each. One is light from the sun, and one is artificial light. No matter what kind of light you choose, make sure you give your plants at least 6 hours of darkness each day. During this time they convert carbohydrates into plant tissue, widen their leaves, lengthen their stems, and grow appropriately. With darkness, the microgreens also grow sweeter and less bitter.


Sunlight is the gold standard. Many microgreen growers place their microgreens in front of a sunny window, and as long as it gets sun about half the day, the microgreens will flourish. If there is not enough room on the window ledge, consider building shelves to fit your microgreen trays. Painting the shelves white offers an even better reflection of the sunlight.

Artificial Light

Depending on where you live and what time of year it is, you might not be able to use sunlight as your only source of light. Winter sunlight is weaker and doesn’t last as long, and often needs to be supplemented with artificial lighting. The good news about artificial lighting is that you don’t have to break the bank for quick growing microgreens.

  • Your plants will grow well under plain white fluorescent light, and you probably already have these kinds of bulbs on hand.
  • Flowering plants and full grown plants grow under full-spectrum light, and if you are a serious grower you already have these for your other plants. Microgreens can grow well with these as well.
  • Using a reflector will offer more light than the sun or artificial light offers. You really don’t need fancy mirrors or equipment. One budget-friendly idea is to use cardboard painted white as a reflector.

If growing vegetables outside, you almost don’t have to think about the light they need. But in order for microgreens to grow wide and full with healthy leaves inside,  they need to have the right amount of light.  Whether you choose sunlight or artificial light or a combination of both, your microgreens will taste sweeter and be more nutritiously dense if you manage their light well.

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