Your microgreens are living plants. Before harvest, keep indoors in a shallow dish where they will receive light. They do need occasional (check daily) water added to the bottom of the dish to let the microgreens soak up the water from the bottom. Greens can be refrigerated live in the tray (except basil) but it is not necessary. Depending on when you buy them, the temperature of your home, the light and the variety, they can last and continue to grow 5 – 7 days. Humid environments with low air circulation and/or over watering can lead to problems. If the grow mix gets moldy (white root hairs are normal and can be confused with mold) or if the greens appear to wilt and don’t revive after a few hours with watering, discard and don’t eat the greens.
To harvest take clean scissors and cut the greens above the grow mix. You are trying to avoid pulling up the roots with bits of grow mix attached. You can cut only what you need for now or you can harvest the entire tray.
Wash/rinse your greens as you would lettuce or any other fresh greens, then place the greens on clean kitchen towels or paper towels to dry. Wet microgreens will spoil quickly so the drying step is important. Once cut and washed, greens should be stored in the refrigerator. Harvested greens can be frozen for use in smoothies.