10 DECEMBER 1994, Page 52

Gardens

A load of old puddles

Ursula Buchan

Atheme, which runs like a never-end- ing stream through our gardening history, is our interest in, even obsession with, water. Fashions change over the years: these days we choose to install kiddie-safe bubble millstones rather than fountains which send plumes of water 300 foot into the air, and we have abandoned the formal pool from which emerges a winged Mer- cury on a stick, in favour of the wildlife pond complete with frog 'beach'. But the impulse is the same.

Attractive as the idea of water must always be, the reality is not without its hid- den difficulties. If your pond is made of concrete it leaks, if it is pre-formed it may be hard to make it look 'natural', if it is for- mal in shape wild animals drown in it while the herons pinch the fish and make the children cry and, if it is 'informal', it can soon become 'wild'. Unless unattractively barricaded, all types of pool are capable of drowning your young children or their friends.

So-called `marginals', that is plants which live in a few inches of water, grow thicker and stronger and quicker than any other kind of plant, because they have been bred in the Pool of Hard Knocks and have learnt a trick or two about thuggery. The Greater Spearwort, the Bogbean and the Reedmaces are names to chill the consci- entious gardener's blood. As for water lilies, some, like Nymphaea alba, know their place about as well as the head waiter of a fashionable L.A. restaurant.

The newly-made pond is particularly prone to problems, because of the minerals which you introduce when you fill it with tap water. These stimulate extravagant green algae growth, esrecially as there is as yet no shade cast by water plants to restrain it. Your friends will tell you that the answer to algae is barley straw suspend- ed in a hay net in the water — but you reply that, to your certain knowledge, such straw is not to be had, no, not even for ready money, in SW13. If there is shade, it is probably cast by deciduous trees, so leaves will float and, worse still, sink, in the autumn; these soon form a carbon dioxide rich sludge at the bottom, which is more than capable of killing the fish. The truth is that water, 'like fire, is a good servant but a bad master and a bad master it often becomes. Nevertheless I 03 in danger of ignoring this inescapable, ineluctable, indisputable fact. Like so Inag before me, I cannot withstand the sir° call, or tinkling splash, of the 'water garden'. Until recently, I have always been a little superior about those of my friends IA° have willingly put themselves through this particular mill. But that was before Mr C. arrived one day, complete with canarY" coloured digger, to push tons of topsoil around the top terrace of the garden, ill a giant's game of Tonka toys. (To call him a digger driver is misleading; he is, in his way, a magician, with great sleight of buck' et — capable of removing a heavy stone wellhead cover and replacing it with minute precision, so that one disbelieves the evidence of one's own eyes). His eyes gleamed when I casually and vaguely pointed in the general direction of the natural depression close to the garden's boundary, and mentioned something about' how nice it would be to have a 'natural pond there — one day. Before you could say `J.C. Bamford', he had scooped a four foot deep hole in the bottom of the depres" sion to check the constituency of the soil. Even Mr C., who is of a naturally optimistic frame of mind, had regretfully to admit that, although the soil was as difficult, to get through as the omnibus edition 0' Brookside, it was not quite clayey enough t° 'puddle' with the front bucket, and therchY make a watertight seal. The words 'that will mean butyl flexible liner at 50 pence 3 square foot, not to mention mY/Y011,1. extremely/pretty reasonable digging rat' per hour' hung, unspoken, in the air between us. Such a course would reduce my expansive pond to an area not much larger than a puddle. Surely this was InY salvation. I could make lots of noises about how disappointed I was not to be able to afford one, but really one does have to he realistic. . . . I had reckoned without everybody else's desire for me to have water in my garden,: A landscape architect friend came up wit' the magic word 'bentonite'. Bentonite is : a, sodium clay, which can be sandwiche between two layers of geotextile, which 'self-healing' if cut. I discovered that stuff costs 68 pence a square foot. Whtic mil Shook my head unhappily at the ruination of all my cherished hopes, she went on to say that there was a dry powder form of bentonite which, although fiddly to deal With because it swells, when wet, into an impermeable gel 15 times its dry volume, would be much cheaper. If you want to know what happens next, watch this hole.