Surprise, the answer is both! Watering Peace Lilies from above and watering from below have their own benefits and drawbacks, so for best results you can mix and match as needed. Top watering is convenient and fast, and good at removing buildups of fertilizer or other nasties. Bottom watering results in deeper, more lasting hydration. Water from below once a month during the summer and spring and water from above the rest of the time. It’ll keep your soil fresh and clean, but still keep that deep lasting hydration a peace lily loves.