I bought the wrong grow light twice. First on wattage, because wattage was the biggest number on the box. Then on Kelvin, because a blog told me 6500K was closest to sunlight. Both trays came out pale and short, and both times I blamed my seed. It was not the seed, and the 2026 research finally told me why.
The blackout period is the dark stretch at the start of a microgreen's life, and it does more than you'd think. Here's why growers keep their trays covered, what it does for stem length and yield, and how long to leave them in the dark before the lights come on.
Growing microgreens in low light conditions involve selecting light-tolerant varieties, such as kale or mustard, and providing supplemental light if necessary. Optimal light conditions for microgreens generally range from 50 to 200 µmol/m²/s, but these plants can adapt to lower light intensities.
Read MoreBeyond the Windowsill: Growing Microgreens on Your Balcony or PatioWhen you visit any web site, it may store or retrieve information on your browser, mostly in the form of cookies. Control your personal Cookie Services here.
