Plants help create a more natural feel in and around your pond, even when your pond is lined with plastic. The plants help shade and oxygenate the water, and some offer safe havens for creatures such as frogs and dragonflies. Instead of dumping soil in the bottom of your pond, help keep the water clean by using individual pots for your plants. This also makes it easy to change out your plants or move them in the winter, and it keeps possibly invasive plants such as water lilies (Nymphaea odorata) contained so they don't take over your pond.
Choose pots with wide tops for your aquatic plants. Most have roots that grow in the top 10 to 12 inches of soil, so pots should be at least 10 inches deep. However, a diameter of 12 to 20 inches gives most water plants room to spread out slightly without taking over your pond. Materials such as terra cotta or plastic pots typically work best for ponds.
Fill the pots within 2 inches of the top with a clay loam soil. This soil is heavier than many potting soil mixes. Avoid mixes that contain items such as perlite, peat moss or bark, as these items will float to the top of your pond.
Dig a hole in the pot slightly deeper than the root ball of your aquatic plant using a trowel. Place the root ball in the hole, and backfill with soil. Add a layer of small gravel to the top of the soil to help hold it in place and to keep fish from disturbing the soil.
Place bricks, overturned pots or cement blocks in the bottom of your pond to act as plant shelves. Depending on the variety, the plants typically need between 6 and 18 inches of water above the pot. Planting them too deep can keep them from developing properly.
Place the filled pots on top of the bricks or other shelf material, lowering them slowly into the water without tipping them to either side.