We've talked about soil for pond plants but what about the containers?
Pond gardeners who have performed, liner, concrete or fiberglass ponds often grow their plants in pots. If you have a earth-bottomed pond, you may also want to plant in containers to keep the plants in one place. The purpose of planting in containers is basically to keep the soil and plant together without dirtying the water or damaging the pond.
There is the solid container, which is highly recommended for pond lilies and lotus. This keeps the lily compact and the plants seem to thrive more in solid containers. You can put your fertilizer directly into the soil with the plant. Since lilies and lotus grow a large root, when planted in a container with holes, the plants will find the holes in the container and grow out of them causing them to fall over or adhere themselves to something else in your pond. If you use a container that has one hole in the bottom make sure you close it with some burlap or material that will keep the hole closed and won't allow the plant to push through it. It is best to have a container with no holes, since sometimes the larger root systems will push through even the material that you have plugged the holes with.
The open weave baskets allow the water to diffuse through all the pot surfaces, enabling the plants to pull nutrients from the water. Some plants are grown for their filtration qualities and these baskets let the roots grow through the open holes to filter the water more effectively. You will probably have to transplant more frequently as the plants mature and their roots break through the holes.
If you have a natural pond and want to plant the pond plants directly into the pond, this can be easily done. You may try burlap bags with soil in them to hold the waterlilies or lotus on the soil below the waters surface. As the lilies or lotus grow, the burlap bags will disintegrate and the plant moves into the soil on its own.
A good rule of thumb would be to always use the solid containers for all lilies and lotus and use the open weave basket planters or containers with holes in them for most bog plants.
Buy containers,planting baskets here.