Plants for phyto-purification

Before we take a look at the most suitable plants for phyto-purification, I will briefly explain how water phyto-purification works.

Aquatic plants, such as marsh plants, submerged plants, and water lilies have the power to purify water naturally, thanks to the symbiosis created between these plants and the aerobic bacteria that live in their roots.

For this reason, you can build a pond in your garden in perfect balance and with clean water, simply by placing the appropriate aquatic plants, without the need of pumps, filters or chemicals. In this regard, if you haven’t read it yet, download the free “Guide to Growing Aquatic Plants“!

Plants for phyto-purification are used in ornamental ponds, koi carp ponds, natural pools, and phyto-purification systems.

Through phyto-purification systems, waste water from civil, industrial and agricultural uses can also be purified.

Plants for phyto-purification capture oxygen from the atmosphere and transport it to the roots of the plant. Then the oxygen is released into the substrate around the roots, where aerobic bacteria live, which are able to degrade pollutants and organic matter into inorganic substances available to the plants.

The plants in turn directly absorb some of the organic matter dissolved in water and produced by the bacteria.

This process results in good quality water, purified from organic waste substances, pathogenic bacteria, viruses and heavy metals.

All aquatic plants, such as marsh plants, water lilies, submerged and floating plants, are useful for phyto-purification, but there are more or less suitable plants, depending on what you want to achieve.

How to choose the appropriate marsh plants for phyto-purification

The choice of plants for phyto-purification depends first of all on the context of what you are creating: ornamental pond, natural pool, phyto-purification system (free water surface systems, subsurface flow system, subsurface flow system with slightly wetted soil, or floating phyto-purification system).

In fact, depending on the context, for example you will give different priority to aesthetics. Maybe you may need particularly hardy or autochthonous plants. And also, with regard to context you will have to choose plants that are appropriate for the depth of planting relative to the water level.

Once the context is established, the three factors for choosing the most suitable phyto-purification plants are:

• Length of the roots (the longer they are, the more they are able to oxygenate the water in depth);
• More or less rapid development of the plant (the faster the plant grows and reproduces, the faster the area covered by plants increases);
• How does the plant behave during the four seasons of the year (e.g. does it suffer from too much heat, does it stop its fuction in winter, or is it easily attacked by aphids?)

The best marsh plants for subsurface flow phyto-purification system with moist soil substrate and lower water level (therefore with only the roots in the water but with the plant collar dry)

The best marsh plants for floating phyto-purification (marsh plants placed on floating rafts)

The best marsh plants for free water surface phyto-purification systems with marsh plants submerged in water for about 10 cm (so including ponds and natural pools)

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