No need to wash baby spinach leaves if you buy it in a box that's pre-washed. To wash other spinach, you can fill a clean sink or large bowl with cold water, add spinach leaves and swirl them around to remove dirt and grit. Lay the spinach on dry paper towel and gently blot away the excess water. If you have a salad spinner, fill it with cold water and soak the spinach leaves. Lift the basket out so dirt falls to the bottom and pour out the dirty water. Repeat if necessary, then spin dry.