Other than Water Lilies - Nymphaea - most pond gardeners tend to neglect the area of deep water that is usually present in most garden ponds.
The 'deep-water' area is normally around 1.5 - 2.5 feet deep (45-60cm). Naturally, it is a little difficult in some ponds to gain access to this area - hence the neglect. Together with that, it is often the most difficult area to clean!
Basically, deep water plants are sunk to the bottom of the pond in a weighted container - normally a special pond basket. It is best to cover the top of the soil in the container with heavy pebbles - not just a light layer of gravel, for the fish that feed on the bottom of the pond - Tench etc - are adept at rummaging about in gravel in their search for food, so will soon make a mess of light gravel toppings!
The foliage and flower stems of the deep-water aquatics grow up to the light and break the surface, either to sit on the pond surface as with water lilies, or grow up to form larger plants that will give some height and interest to the centre of the pond. Down below - out of sight, the plants will also provide hiding places and shelter for fish.
The all-time favourite deep water plant for garden ponds has to be the Water Lily - Nymphaea if you are feeling posh! It will emerge from the depths of your pond in the early spring. With flowers that sit neatly on the surface, there are no problems in trying to keep them tidy in windy conditions!
An added advantage of deep water plants, is the fact that they provide cover which shuts out some of the light from the depths of the pond. This will help in preventing algae to a certain extent. The plants use of nutrient from within the pond will also deprive algae from much needed or excess nutrients.
Most deep water aquatic plants prefer still water, but there are also some that will tolerate being planted near to a waterfall of fountain.
Some Deep-water aquatics