You can wash it prior to storing but I chose to store it unwashed.
Unwashed leaves will give you less moisture to worry about. Amaranth can be stored in a Tupperware dish or in a ziplock bag.
Pluck the leaves from the stem. The main stem is not editable and will take up unnecessary room.
Line a ziplock bag with paper towel help capture excess moisture and prevent quick spoilage.
Pack the leaves in the bag and lightly push air out. Be careful not to squish the leaves as it can cause the leaves to spoil faster.
Now place your bag in the crisper drawer! It should be good for at least a week or more. Remember to change the paper towel when it becomes moist, squeeze air out after opening and wash before eating!