Pond plants are used as they feed on the nitrates in the water column and some species will even consume small amounts of ammonia and phosphates from the water column as well.
Deciding which species of pond plants that you wish to add can depend on the size of your fish pond or even the overall shape, with irregular shaped ponds that have a corner that sticks out, a group of taller pond plants such as rushes can give these corners a natural look and help the fish pond to blend in with the surrounding garden space. Getting the balance of pond plants is just as important as the variety, adding too few plants will mean that the nitrates levels will rise in time causing you to perform a higher number of partial water changes before algal outbreaks occur, adding to many plants can mean that your fish pond will become overgrown over time leaving little swimming space for your fish.
In some natural fish ponds the overgrown look is actually welcomed as the plant life takes prevalence over any livestock that may or not be added, a lot of Koi fish keepers will not entertain pond plants in their fish ponds and prefer to control the water parameters themselves.
As with the number of plants required for your fish pond, the different planting depths have to be taken into consideration, marginal pond plants normally sit on shelving that is incorporated into the fish pond design while other species of pond plants such as the water lilies prefer to be sited in baskets of aquatic compost at the bottom of the fish pond. Plants can also be used on the perimeters of the fish pond to break up the hard outlines of the pond, adding bushes or grassy foliage plants around the edges of the fish pond will help the pond to blend in, bog plants can also be used to great effect by creating marshy areas at the side of the fish pond.
Taller pond plants should be planted at the rear of the planting areas and shorted varieties planted at the front to give the best effects, plant in groups at random rather than regimental planting, this can create a false effect rather than plants grouped together with the odd are of minimal planting. Whichever pond plants that you decide to use, always research their needs, all sites or suppliers that sell the pond plants should be able to give you the correct information for planting depths, how tall the plants are expected to grow and whether or not they will delight you with a colourful display of flowers through the summer months.
All pond plants can be split into several main groups to make it easier for you to plan on which species that you wish to add to your fish pond, they are as follows
Marginal PlantsMarginal pond plants live on the edges of the fish pond or slightly submerged on the shelving of the fish pond. Bog plants are also part of this group but I like to keep these separate as to me marginal plants should be placed on the shelf in baskets with a very small amount of water over the top of the basket, to me bog plants can be set on the side of the fish pond in marshy areas where the soil is waterlogged but the plant roots are not submersed. All marginal plants should be placed in a basket of aquatic soil and this should then be covered over with a layer of gravel to protect the root system of the plant from fish nibbling away etc. Using this method can prevent the roots of the plants from becoming invasive in the fish pond and allows all of the marginal plants the opportunity to grow well and provide a stunning display in the summer months. Never place marginal pond plants in ordinary soils or compost, these can contain shredded wood pieces that will rot and foul the water or even cause rot in the plant itself. There are many examples of true marginal plants to choose from and even these may have different planting depths on the same length of shelving so always check and you may find it necessary to raise the planting basket slightly to get the required depth.
Examples of marginal pond plants include
Calla Palustris (Bog Arum), this delightful little plant produces small white flowers and is actually a UK native plant.
Equisetum Scirpoides, this plant is like a dwarf rush and only grows up to 30 cm in height. It grows in a very compact bunch and has a rich green colouration on its leaves.
Lysimachia Punctata, small yellow flowers speckled in maroon and brown spots are produced by this plant , it does not grow to tall and will quickly settle in the margins of the fish pond to fill the spaces with colour.
Bog PlantsBog plants are very similar to the marginal fish pond plants but tend to be planted on the pouter perimeters of the fish pond and enjoy marshy conditions. This can be replicated quite easily by allowing a larger overlap from the fish pond liner or placing plastic sheeting underneath the top soil so that moisture cannot drain through the strata. This means that the growing medium remains moist and damp at all times which suit the bog plants encouraging good growth. As mentioned above marginal plants and bog plants are very similar, some fish pond keepers will even treat the bog plants as marginals and place them on the fish pond shelving.
Examples of bog plants include
Primula vulgaris (Native Primrose), a low growing plant that can produce a variety of different coloured blooms for several months.
Osmunda regalis (Royal Fern) A great foliage plant to fill unsightly gaps around the fish pond. Being a fern, they will not produce flowers but make a good contrast to flowering varieties of bog plants.
Rheum palmatum (Giant Rhubarb) this plant can grow up to 6 feet tall and will produce flowers in the early summer months. These will die off quickly leaving reddish tinted foliage making this a great specimen plant.
Oxygenating PlantsThis group of plants play a key role in the fish pond, releasing oxygen into the water column thus keeping your fish healthy and long lived. Keeping the oxygen levels high will also aid with keeping the fish pond water clear and free from algal outbreaks. Oxygenating plants are high consumers of nutrients in the water and will quickly out compete any algal spores for these thus the spores die off while the plants thrive. These plants are usually sold as cuttings, some may be potted already or sold loose and bunches of the cuttings are placed in aquatic soil which is housed in the appropriate baskets.
One word of warning when adding these, if you have over planted they will produce CO2 at night which will reduce the oxygen levels and can leave the fish gasping in the mornings, they should be planted at one clump for every sq metre of water surface.
Examples of Oxygenating Plants
Elodea crispa - A very popular plant that produces long, slender stems. They are very easy to grow and may need thinning out on a regular basis.
Potamogeton crispus this plant produces leaves with a curled edge and is often known as curled pondweed. Another fast growing plant which should do well in any fish pond.
Potamogeton Natans, a very similar plant to the above but produces broader leaves that do grow very fast and will need regular pruning.
Floating PlantsFloating plants are ideal for removing nitrates from the water column; their root systems grow downwards into the water soaking up the nitrates and phosphates very efficiently. They also make great plants for the fish fry to hide in and for amphibians to lay their eggs.
Most species of floating plants tend to look very similar but do vary in leaf size. They normally consist of a group of leaves attached at the top of a stem and they multiply by sending out a runner with plantlets attached. They will need thinning out occasionally and if the nitrate levels in the water are low they can quickly die off if nutrients are not supplemented with a liquid feed.
Examples of floating plants
- Straitiotes aloides (Water cactus)
- Lemna minor (common duckweed)
- Pistia straitiotes (Water Lettuce)
When adding these to the fish pond, never place them directly on the bottom of the fish pond unless it is a shallow one, they should be lowered gradually, the basket supported at each level until it is re-positioned. Each plant should be supplied with a planting depth for when you first add them to the fish pond and also a maximum depth, this is the maximum depth that the lily should be kept at on a long term basis.
For the smaller fish ponds there are the
Laydekeri Lilacea that produces pink flowers, Froebelii Water Lily that produces red flowers and when you start o plan for the large fish ponds you can try the Alba Water Lily or the Colossea Water Lily. Of course there are many more varieties to choose from and the previous are just examples.
Whichever planting plan you decide to go for, research carefully about the preferred growing conditions and make sure that you do not over plant the fish pond. A good balance of pond plants will still look natural as well as helping to purify the fish pond water!