No, the idea that microgreens need direct sunlight keeps many people from trying to grow them. These tiny plants do great under many light sources. Indirect window light works. LED grow lights work. Even basic shop lights can do the job. The source matters less than getting enough light for enough hours.
I tested this myself by growing the same radish seeds in three spots around my house. The south window made stocky dark green plants in 8 days. The north window grew taller stretched stems with lighter color. Those took 11 days to reach the same size. My LED shelf gave the best results of all. Compact plants ready in 9 days no matter what the weather did outside.
What matters is light strength, not the source. Experts measure this in PAR or foot-candles. A bright window puts out 200-500 foot-candles on a sunny day. A good grow light set 4-6 inches above your trays hits 800-1200 foot-candles. Both support healthy growth. The window costs nothing but changes with weather and season. The light costs money but stays steady.
Penn State Extension says microgreens need 4-6 hours of natural light daily for decent results. Using microgreens artificial light extends that time to 12-18 hours daily. Why longer? LED light is weaker than direct sun even with good bulbs. Running them longer makes up for the lower power. You end up with similar results either way.
You can grow microgreens without sunlight in basements, closets, or rooms with no windows. I know growers who run their whole setup in a spare closet. The results match or beat what windows produce. Light stays the same whether clouds roll in or the sun shines bright. Temps hold steady away from cold window drafts in winter. Many sellers prefer this control over fickle natural light.
Your choice between natural and artificial light comes down to goals and budget. Sunny windows cost nothing extra to use. They work great for casual growers who accept some ups and downs with the seasons. LED grow lights run about $25-50 for a basic setup. They pay off fast if you want steady results all year. I started with windows and added lights after my first frustrating winter.
Light distance matters more than new growers think. Keep grow lights 2-4 inches from your plant tops. This stops the stretched leggy growth that happens when plants reach for far away light. Raise your fixture as plants grow taller. Or start higher and lower it as seeds sprout and develop. Either way works fine.
Watch your plants for signs of light trouble. Stems that stretch tall with small pale leaves need more light. Move them closer to the source or add more hours. Leaves that curl or turn brown might get too much direct sun through a window. Shift them back from the hot glass. Let the plants guide you more than strict rules.
My advice is to start with whatever light you have and see what happens. A bright window costs nothing and teaches you the basics. Add grow lights later if you want better results. Build up over time rather than buying gear you might not need. Your plants will tell you what they want once you start paying attention to them.
Read the full article: How to Grow Microgreens Indoors at Home
