[header] How to keep green onions fresh [title] Fill a glass or tall jar with 1-2 inches (2.5-5.1 cm) of water. [step] Use a glass or jar that is heavy on the bottom so that it easily stays upright. The water should be cold or room temperature, but not warm. 
[substeps] The glass or jar should be tall enough so that it can keep the green onions upright. For example, a pint glass or a large canning jar works well.