Oz Watergardens Zone4 is a guide to aquatic plants that are ideal for pond depths from 20-40cm deep.
These plants are ideal for a small garden pond. Whereas, in a well balanced larger pond, they are the transitional plants between the pond edges and the deeper water.
They can be divided into two distinct types
- Underwater plants that grow with their foliage totally submerged underwater, such as Ribbon Grass (Vallisneria).
The foliage of the underwater plants is often thinner and more delicate. This foliage tends to break more easily and for some of the underwater plants, allows them to drift and regrow in other parts of the pond. Care should be taken when selecting some varieties. Some varieties of underwater plants, that have been popular in aquarium's, have become troublesome weeds in natural waterways. Check out our aquatic weeds page and enquire with your local or state departments for further information.
Underwater plants are often referred to as oxygenating plants, providing oxygen to the water during the day. The underwater plants play a vital role in improving water quality and clarity. The leaves and roots act as nutrient sponges, removing potentially toxic elements.
- Emergent water plants with foliage both under the water and also on or above the water surface, such as Water Milfoil (Myriophyllum species), rushes and sedges.
The emergent foliage also reduces sunlight penetrating the pond water and so shades out the algae growing in the water below. Some provide shelter and protection for aquatic life, creating areas for fish and frogs to lay their eggs and spawn. Smaller fish also have a better chance of survival as they provide excellent place to hide from the larger fish.
Small Garden Pond
The choice of plants for a small garden pond is only limited to the space that you have available and the desired outcome of your creativity. Choosing an assortment of plants from Zone 4 can add a variety of colours as well as height levels to your display.
Large Garden pond
In a large garden pond the Zone 4 plants create the environment between the pond edges and the deeper water. It is important to select plants from all 5 pond zones in order to create a healthy pond ecology.
The Zone 4 pond plants also help protect the fish from predators such as cats, by creating cover over the pond surface and leaving the open clear water further from the pond edges. When the fish do come closer to the surface they are out of reach and less likely to be in harms way.
You should select plants to help create an environment that will benefit the fish and other aquatic life. Some emergent plants are needed to provide shade with their floating leaves (Water poppy - Hydrocleys nymphoides), while others form trailing mats that create places to hide and spawn in (eg. Water Milfoil - Myriophyllum species). Many aquatic plants encourage or attract other insects and organisms that the fish or frogs can feed on. Some underwater plants should also be included to provide oxygen and help improve the water quality through natural filtration.