How to build a wildlife pond

Alan Titchmarsh makes a lake.

It’s said that the author Robert Graves, who penned some of his finest work in Majorca, found the prospect from his window at Deià so beautiful that he was forced to build a wall to screen the view and avoid distraction. I know exactly how he felt and, tempting as it is to feel that if I did the same, it would improve the quality of my prose, nothing whatever will induce me to build a wall outside the floor-to-ceiling windows through which I gaze as I write.

My desk sits just a few feet away from them and they overlook our wildlife pond, constructed about 10 years ago. It has become a magnet for all manner of birds and amphibians and also for my gaze as I watch the seasons change and, with them, the ebb and flow of the natural world.

This is about the best time of year to construct any kind of water feature, but most especially large ponds and lakes, as the earth is beginning to warm up and aquatic plants will romp away rapidly to help it blend into the landscape. In days of yore, such ponds were made of puddled clay trodden down by a flock of sheep driven over and around it for several days until the base was rendered impervious to water. A stream could then be diverted into it and nature left, more or less, to take its course.

Today, we resort to easier-to-handle butyl sheeting the material that was used to make my own 65ft by 100ft pond. Butyl will last with luck for a good 20 years if used properly, so it makes sense to buy the best quality and do the job thoroughly at the outset. When the mechanical digger excavates the hole, it pays to plan where the spoil will be deposited before you start. Nothing looks more obvious than a mound of earth next to a pond try to craft it into the landscape or else move it away completely.

No pond needs to be deeper than 40in at its centre, with ‘shelves’ created around the perimeter for marginal aquatic plants that enjoy life in the shallows. The final surface should be firmed and smoothed with either a mass of trampling feet or else employ a ‘wacker plate’. Next comes a 2in layer of sand, over which is spread pond underlay. This material looks for all the world like thick carpet underlay and is vital to prolong the life of your liner. The sand and the underlay are insurance against punctures.

The butyl is stretched over the top and any creases made neat before yet another layer of underlay material is stretched over it and topped with 3in–4in of topsoil. This might seem like a lot of trouble to go to, but ponds and lakes constructed in such a fashion won’t leak should a neighbourhood cow stray into them or the local herd of deer take up residence.

If the layers can be so buried at the edges that they allow for a boggy margin, then vegetation will rapidly help your pond to blend in. Submerged oxygenating plants will be needed to keep the water clear and ‘fixed floating aquatics’ such as waterlilies can be added in a month or two so that they can expand throughout the summer. In small ponds, they can be planted in plastic baskets; in lakes, they’re best grown in enclosures installed before the pond is filled, made from a couple of old car tyres stacked on the bottom and filled with earth (not compost, which can foul the water).

An island or a duck house will soon be colonised by mallard and/or moorhens (we play host to both) and frogs, toads and newts, dragonflies and damselflies, pond skaters and water boatmen will quickly take up residence. Our greatest delight has been the occasional kingfisher ample compensation for the effort it took to transform a forest of nettles into a ring of bright water.