Soak sunflower seeds. Add sunflower seeds to a jar and top with plenty of water. Allow them to soak for 8-12 hours or overnight. This is the only time the seeds should sit in water.
Rinse and drain. Rinse and drain the seeds well using a strainer every 8-12 hours (twice daily) until first signs of germination when you can see tiny little shoots appear.
Add seeds to a growing tray. Wet the growing mat and squeeze excess water out. Place inside a tray or dish then spread the seeds out evenly over the top.
Cover. Cover the tray with an inverted lid then add something heavy on top to weigh them down for the first few days. I like to use a tin. For larger trays use more than one tin or maybe a brick.
Keep seeds moist. Mist the sunflower seeds lightly with water twice each day (morning and evening) to keep them moist, being careful not to over wet.
Expose to sunlight. Once the sprouts have grown to about an inch tall, remove the lid. Place the tray somewhere bright so they can grow tall and start to green.
Water twice daily. Check the greens daily, morning and evening, and water lightly. See notes below.
Harvest when ready. You can harvest the sunflower microgreens from a few inches tall, typically after 10-14 days. By this time they may be 6-8 inches tall. Using a pair of scissors, snip from above the mat. Rinse and lightly dry on paper towel before use.