Just as all garden plants require different growing conditions, so do water plants. There are plants that prefer to float on the water, plants that will happily grow quite deep, and many others that grow somewhere in between. A good rule of thumb is to aim for about 50% coverage of the water surface with plants.
A well designed water garden will include (where pond size allows), plants that will grow happily in all depths. This will make it easier to reach a good balance in your pond which in turn decreases any problems you may have. If adding fish be sure to only add the correct number for the pond size, and don’t overfeed as this will add too many nutrients to the water.
The Different Planting Depths
- Floating plants do just that, float freely on the water surface. They offer shelter, breeding habitat and food for fish. Will shade the pond and help prevent algal growth.
- Bog plants grow around the margins of the pond and will tolerate seasonal flooding, catch excess rainfall and prevent erosion around the pond edges. This in turn will protect the edges from damage by cats or dogs. They can attract and harbor wildlife to the pond, such as lizards, birds and frogs.
- Marginal plants grow in shallow water to a depth of about 20cms. Not only do they make the edges of the pond more attractive and hide unsightly wiring, they can also offer shelter for fish and frogs. Also a good plant choice for shallow pots.
- These plants grow with their foliage totally submerged at a depth of 20-40cms. They play an important role in water clarity by oxygenating and removing toxic elements from the water. Some plants will also have foliage above the water providing shade keeping the water cooler and decreasing algal problems. They can provide shelter for aquatic life to spawn, protection from external predators and even protect the smaller fish from the larger fish.
- Deeper growing plants greater than 40cms, provide shade for the water surface, help reduce evaporation and shelter aquatic life from predators. They can also improve water quality through oxygenating, filtering and consuming nutrients.
Soil for potting
Ideally soils should be not too clayey and not too sandy, but rather a good mix. A clay loam will do, especially if you know it grows great veges. Just dig the soil from your garden as long as you know it is not contaminated. Alternatively aquatic mixes are available commercially.
Pond Maintenance and Cleaning
Regular cleaning and maintenance of your pond will reduce the occurrence of murky water, algal growth and dead fish. Removing any dead foliage and windblown debris on a regular basis will minimise the workload and result in a healthier more vibrant pond. Ponds under or near a deciduous tree will need the fallen leaves removed in autumn before they fall to the bottom of the pond. As the temperature warms up in spring these decomposing leaves release large amounts of nutrients into the water which in turn can promote algal growth.
Plants should be fertilised as they start to put on new growth in spring. Pond fertiliser tablets are available, but be careful not to over fertilise as this can add nutrient overload to the water and encourage algae. Make a hole in the soil with your finger, pop the tablet in and cover with soil.
A healthy balanced pond should need only occasional water changes. Spring is a good time for this, removing about 25% of water only. Your pond contains many beneficial organisms so you do not want to upset the balance by removing too much water. Spring is also a good time to replenish your supply of plants to reach 50% cover of the pond. Each pond is unique and for this reason the time it takes to achieve a healthy balance can vary, anywhere up to a year.
Check and clean any filters you may have in your pond. A healthy pond with the right balance of plants and fish can be maintained without the use of pumps. Larger ponds can be easier to maintain than smaller ones.