Wherever you live, winter is here and we all feel it. My husband is still on Kauai, and I am in Colorado. He reported a temperature of 63 degrees yesterday...brrr...while I report about 20 degrees F.
So what do you need to do differently to grow microgreens in the winter? If your home temperature averages 65 degrees F or greater, you are probably going to do fine. The seeds may propagate a little more slowly.
If you have some concern, you could purchase a propagation mat for them, such as: http://www.greenhousemegastore.com/product/seedling-propagation-mat/heat-mats-chambers. I used this to get the seeds rooted after soaking and sprouting (or not as my book recommends for certain seeds). Chilly window sills might be avoided during the initial rooting and cover the planting tray with an inverted planting tray. I sometimes continue doing this at night during cooler periods.
All microgreens seeds like any other plant seeds, need consistent damp soil and darkness until they root and appear on the soil surface. Most microgreens do not need any direct sunlight or grow lights except for sunflower greens. All microgreens will appreciate indirect light once they have rooted. Air flow as suggested in my book is also important. Our houses need to be warm and insulated in the winter while allowing some air movement.
Feel free to ask questions or send me pictures if you need support. I can be reached at firstname.lastname@example.org