Deep water plants, such as water lilies and rushes, are an important component of any well balanced pond or wetland design. At Oz watergardens we classify plants by the water depths that they are best suited to. We have developed an easy to use pond planting guide (refer to our Zone Map page) classifying deep water plants as those that prefer the water to be at least 40cm deep. To view or select plants check out Zone Four and Zone Five.
What are the benefits of deep water and deep water plants in my pond?
Large areas of shallow water create problems in pond management. The upper layers of the pond change temperature more rapidly, affecting not only the growth of plants, but also the fish and other aquatic life. Algae becomes more of a problem in shallow ponds as the sunlight easily penetrates the upper water levels, the water warms up quickly and creates the perfect conditions for an algal bloom.
Improved pond health
The deep water plants become even more important as they shade the water surface (eg. waterlily leaves), reducing the evapouration and water temperature while still providing some shelter from predators. Deep water plants such as Ribbon grass are great water filtering plants and consume large amounts of nutrients from the pond water. As they grow and photosynthesise, they also can improve the oxygen levels.
More stable environment to survive drought
Deep water plants have the added advantage of surviving longer in drought conditions. Large deep ponds, lakes and dams, in areas of low rainfall may have restrictions on refilling or topping up the water levels. As the water evapourates, the water levels fall and the plants on the ponds margins may become exposed and die back. The fish and other aquatic life are left to live in a smaller volume of water that can start to become more concentrated with mineral salts, decaying leaves and fish waste. The decreased pond volume can also increase in temperature. This change in the balance of the pond can contribute towards the water becoming toxic and also reduced in oxygen.
What can I do if I am not allowed to build a deep pond?
Many government departments take issue with this subject. Do you need a pool fence? How deep is it allowed to be? In short, the real answer lies in what the water is used for. If the intention is to swim in the water, then it’s a swimming pool that needs to have a fence built around it. If the intention is to be a water garden pond then technically not. If this were not the case then every council pond, park lake, farm dam or the beach for that matter, would need a pool fence around it.
Some council by laws, state that a pond is not allowed to be any deeper than 30cm. Not exactly ideal for a well balanced pond design. Have you looked at a nice urn in a garden centre and thought that it would make an ideal water feature. Most are more than 30cm deep. Imagine a 40cm deep decorative urn on a high rise apartments’ balcony, with a pool fence around it. You will need to contact your local council prior to building your pond to find out what their regulations are.
There are some solutions, such as a screen placed 5 to 10cm below the water line. Black, powder coated aluminium security mesh is our recommended choice for this purpose as they camouflage well, are strong and most of all – light weight. The latter is most important when it comes to doing any pond maintenance as they need to be lifted out of the pond again. Deep water plants can still grow up through the mesh, provided that the holes aren’t too small, 5cm diameter will still be sufficient. Water lilies produce leaves from their submerged crown. The leaves remain curled up and are able to pass through the mesh and open up to float, once they reach the surface. Rushes produce slender vertical leaves that will easily pass through the mesh.
Rocks and pebbles placed carefully around your potted pond plants. For example if your pond was 50cm deep. The average 20cm pot stands 20cm high. You could place the potted plant in the bottom of the pond and fill the pond up with a 20cm thick layer of pebbles. In essence you create a false floor and the free pond water would only be 30cm deep. This is also a great way to help stabilise taller deep water plants and prevent them from blowing over in less sheltered water gardens.
- To choose your selection of deep water plants refer our Zone Map page and check out Zone Four and Zone Five.
- For information on the plant care and maintenance, go to our Tips & Hints page.