Plant marsh plants directly over the edge of the pond in the wet bank, or the bog area. Here, the plants will have good access to pond water which will keep the soil wet. Marsh plants can grow in water up to 15 cm deep, but you will usually see detailed information on the plant’s label. You also need to make sure your marsh plants don’t run wild. It is best to keep fast-growing plants in pond baskets to keep them under control. You can fill these baskets with pond soil or substrate, which you cover with gravel.