Step-by-step instructions to grow your own windowsill microgreens
5. Once the seeds have germinated (i.e., poked up through the soil), which should take 3 to 5 days, make sure your emerging microgreens get 12 to 14 hours of light per day. (At darker times of year and in certain regions, you might need to invest in a grow light.) Keep the soil moist at the roots, but try not to saturate the leaves.