Fill a 6-inch pot to about 3/4 inch below the rim with a good commercial potting soil. Set the pot in a shallow container of water until the surface feels moist to the touch. Take it out of the water and allow it to drain freely for about 30 minutes.
Sow arugula seeds about 1 inch apart on the soil surface. Cover with ¼ inch of soil. Fill a plastic spray bottle with water and spritz the soil surface enough to evenly moisten it.
Pour some small stones into a plant saucer and set the pot on the stones. This will allow the arugula to drain well and keep the pot out of water. These plants don't like wet feet and will rot quickly if allowed to stand in water.
Set the arugula in the brightest spot in your home. Pick a cool room, if possible. Your arugula seeds will sprout in about two to seven days.
Water your arugula enough to keep the soil moist but not soggy or wet. Don't allow the soil to dry out.
Harvest your arugula when it's about 28 to 40 days old and the leaves are still tender. Pick the outer leaves off at the base of the plant. Allow the inner leaves to continue growing.