How to create a sustainable water feature in your garden

Gardeners’ interest in ponds and water features shows no sign of drying up, says Peter Dowdall.

There was a time that seemingly every garden had or needed to have the ubiquitous “water feature” or pond. Whilst the trend for water gardens has not dried up, excuse the pun, it has certainly lessened in recent years. Gardening is like any other walk of life in this regard, it goes through fads and stages, elements in design come in and out of fashion.

Self-contained water features such as those you will find in any garden centre are a simple way to introduce water into the garden. They are easy (just plug them in), safe (there is rarely any exposed water to create a hazard), they don’t need to be connected to a water source (just fill them once and the water recirculates), they are relatively inexpensive and, most importantly of all, they introduce the wonder of water to your garden.

A garden should appeal to all the senses and not just be a visual treat. Flowing water introduces a feeling of movement and sound. Hearing the water splashing is restful and calming and also, if sited correctly within the garden so that you can hear it before you see it, it will encourage garden visitors to travel through the garden to discover where the sound of water is coming from.

Any water source in a garden will have a beneficial effect on wildlife and should be encouraged. Do try and use rainwater to fill your feature or pond in preference to water from a tap or hosepipe as mains water can contain too much chlorine. In general, bigger is better when creating a pond if sustainability, helping wildlife and promoting biodiversity is your aim. Larger ponds will allow for a more self-sustaining ecosystem and will support a broader range of wildlife.

Much thought should be given to the siting of a garden pond.

The obvious hazard is someone falling into it and suffering from feeling like a fool, if not far worse

Don’t site your pond at the bottom of a slippery slope or in the middle of a children’s play area. The risk of drowning from falling into a pond can be reduced by fitting a metal grid at, or just below, water level. This must be fitted correctly to ensure that it will take the weight of someone standing or falling onto it. It may also be sensible to fence around it.

The pond will need to be lined with a rubber liner or similar and this will need to be higher than the margins at soil level to prevent water loss over the top of the liner. Make sure to create several layers or depths in the pond as this will allow you to use a broader range of plants and thus provide food and habitat to a wide range of wildlife.

Aquatic plants are broken down generally into four types, namely floating, deep-water, marginal and bog plants. Use a heavy loam aquatic compost when planting into the pond and cover the plant baskets with a layer of grit or gravel to prevent any soil seeping into the surrounding water.

Ponds can have problems with algae growth such as blanket weed and also with floating pondweeds. The most important factor to get right and will help to prevent much algal growth is the light level reaching the pond. Too much light will lead to increased algae bloom and too much shade will prevent plants from growing well and thus less oxygen in the water.

The amount of light reaching the water is further affected by the water/vegetation balance. Between 25% and 40% open space is the recommended balance. Maintain this by removing excessive plant growth whenever and wherever it is necessary

Due to worries re invasive species, it is better to use native aquatic plants. These plants will all act as oxygenators. An Oxygenator or oxygenating plant is one which is completely submerged in water, absorbs Carbon dioxide from the water and releases oxygen into the water. Most but not all have their roots in soil.

Oxygenating plants play an important role in maintaining the correct balance in the water as well as providing shelter and shade for fish and reducing algae growth

There are many plants to choose from which will suit the different areas of your pond. The best of all the deep-water plants is the Water Lily or Nymphaea. Look for a particularly good cultivar Nymphaea ‘Marliacea Chromatella’ which produces creamy white flowers.

The marginals and bog plants are where you have the widest choice but do be careful as many of these are vigorous to the point of being invasive. Marginals such as Caltha and Iris have their entire rootballs submerged in the water and their foliage is above the water level. They work beautifully in an informal pond at blurring the outline or the perimeter of the water and the change between the marginals area and the bog garden becomes obscured.

Bog plants are, as the name suggests, plants which like to grow in damp and often waterlogged soil but won’t tolerate growing in water, Gunnera, and Rodgersia are two of the larger and more structural examples but smaller plants such as Astilbe, Hosta and Hemerocallis will give great flower colour as well as foliage effect.

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