Creating a Wildlife Pond

WHY?

The ideal psychological profile for a wildlife pond maker is that of a romantic ecological spendthrift workaholic. Creating a wildlife pond is quite expensive and very hard work, but oh the romance!

WHAT AND WHERE?

To get adequate diversity, and be commensurate with an allotment plot or large domestic garden, aim for a medium size pond with a surface area around 10 sq metres. Mine is kidney-shaped with a curved spine length of just over 4 metres (14ft) and maximum width about 2.5 metres (8ft 3ins). As explained later, it needs to be internally terraced and have a maximum depth of 70-90cm. The capacity of ours is 3300 litres (725 gallons) so the weight of water in it is over 3 tons and the weight of the displaced soil 3.5 tons. It took nearly 3 hours to fill by hose from the mains. You won’t want to empty it for cleaning or repair.

Wildlife wants a site that is quiet with private nesting, home-making, hunting, mating, hiding, sleeping, hibernating spaces nearby. You want a site that is good for little else; for example a wet frost pocket with heavy clay soil, for safety’s sake out of sight of unsupervised passing children. Falling leaves from overhanging trees can be a nuisance. We had a bottom corner with overgrown fenced-off railway embankments to the line on one side and abandoned sidings on the other.

HOW?

Do the planning first! Choose a pleasing profile by laying out rope or a hose, and peg the perimeter. To maintain clear water it is much better to plant in aquatic containers than to have soil on the bottom, so the cross-section must be terraced with flat shelves. One end should be gently shelving to a sand or pebble beach for moisture-loving plants and for animals to drink or bathe. If the site is in a hollow, build robust raised banks from the excavated soil, which reduces the digging. Otherwise, think about where the water will go if the banks burst. Use a spirit level to check that the sides are the same height. Make very very sure that the inside is smooth and free from stones, glass and pot shards, roots etc. that might puncture the lining under high pressure and cause a leak. New dwarf willows or bamboo etc. must be far enough away to avoid root intrusion. Cost and decide on the edging material needed to fix the perimeter and protect the liner - turf, timber, rock, cobbles, paving. Shape and tamp the edges accordingly and add a foundation if necessary. A thin layer of bedding mortar aids stability - decide whether to place it under or over the liner.

It is useful to build a moveable bridge for reaching the central depths.

WHEN?

Autumn or spring. Aquatic plants need the warmer seasons to establish themselves and retailers are fully stocked in spring. Gardeners are less busy in autumn and soil is not too wet and heavy. Filling a new pond with water in autumn or winter is an opportunity to get the upper hand over algae, which normally flourish in mineral rich tap water but are checked by the cold. It takes only a few days for chlorine to dissolve out of tap water whatever the season. There is the prospect of using winter rain to partially fill the pond, though foxes might damage exposed liner with their claws. With its dry winter and wet summer, rain and evaporation were in near balance in 2006/7. Water butts hold 200 litres and are useful for topping-up.

Lining and Underlay

The lining needs to be:

1. watertight;
2. mouldable to irregular shapes;
3. chemically and biologically inert;
4. resistant to roots, stones, animals;
5. resistant to UV light;
6. repairable if damaged;
7. not too heavy, for transport and fitting;
8. affordable.

 

RIGID OPTIONS

1. Premoulded Fibre-glass. Small size and shallow. Difficult to achieve a snug fit to underlying soil so prone to stress cracks. Quite expensive.
2. Concrete. Ugly and complicated. Need blocks or shuttering to make shelves. OK for vertically-sided rectangular fish ponds.

NATURAL OPTIONS

3. Clay. Very heavy, expensive to transport. Pond must be at least 17 feet square to achieve gently sloping sides. Difficult to make totally waterproof. Vulnerable to roots, worms, moles.
4. Bentonite. A volcanic ash from Montana. Used as loose granules or in a heavy impregnated mat. To avoid chemical leaching cover with 15 inches of soil – so extra excavation required. Costly.

FLEXIBLE OPTIONS

5. Polythene. Cheap. Becomes brittle under UV light. Expect to replace every 3-5 years. Cannot join; difficult to repair.
6. PVC. First advance on 5). Lasts 5-20 years depending on grade. Thicker grades unwieldy for irregular shapes.
7. LDPE (Low density polyethylene). High tech polythene from ICI, often with 3 laminated layers. Snug-fitting. Different grades guaranteed for 15, 25, 40 years. Best buy at about £1.50 per square metre.
8. Butyl. Rubber-based Rolls-Royce product with superb elasticity. Very long life; easily repaired. Join by heating edges. Heavy and expensive. Too posh for allotments.

Underlay is recommended. Sand is useless for slopes; old carpet and newspapers rot; inverted turf is vulnerable to roots and burrowing creatures. Manufactured geotextile membrane is excellent and costs from £1 per square metre. It is often discounted by suppliers if bought with a LDPE liner.

You need a total length of at least (pond length + twice max. pond depth +1 metre) to allow for edging, and similarly for width. With irregular shapes allow for folds.

I found no regional retailer with a useful range of stock. Most Ebay sellers are corporate with high delivery charges. A Google search found mail-order outlets, mostly on Teesside near the ICI works, catering largely to koi carp enthusiasts. I used www.pondkeeper.co.uk who charged under £60 including delivery for 15 year LDPE and geotextile underlay for 6m by 4m sheets. I actually got 6m x 5m LDPE because they were out of stock of the 6m x 4m.

The water level of the pond varies seasonally and is lowest in the heat of summer, potentially leaving more liner exposed to sunlight round the edges. Fringe vegetation helps. I had spare pieces of stone crazy paving from home and rested them nearly vertically on the first shelf.

Planting

Planting, of both a wildlife pond and its surrounds, is a combination of aesthetic, environmental and severely practical considerations. Aquatic plants are categorised by either their average water depth or their function and these do not coincide.

DEPTH

For plants in containers depth is measured to the top of the growing medium - a plant for 50cm depth really needs 70cm from the surface to its shelf. Very many aquatic plants prefer depths in the range 5-30cm so ponds need a generous first shelf, which can be a spiral ramp to the surface from a 45cm depth and be double width in places. A second shelf catering for plants wanting 40-50cm depth does not need to occupy the entire perimeter. Only a few plants, including water lilies, want really deep water of 60cm or more but they are big, so make the base at least a fifth of the surface area. At depths over 80cm the temperature is even and the water will not freeze in winter.

Depth requirements are not an exact science. Suppliers and books may disagree in their recommendations; many plants seem to be tolerant of a range of depths and there will be seasonal variation. If necessary, pots can be raised by sitting them on bricks or stones. Beware! The term marginal, applied to shallow water plants, is unhelpfully broad because it includes bog plants happy in damp soil and others that need constant submersion to 30cm.

FUNCTION

A still pond needs oxygenators to refresh the water for its inhabitants and to check the growth of green algae by absorbing dissolved mineral salts, the main food of the algae. Many, but not all, oxygenators are delicate floating plants; some are not hardy; some proliferate madly in summer; some sink in cold weather. Oxygenators absorb carbon dioxide and give off oxygen during daylight, but the pattern is reversed at night so reduced winter numbers are sensible.

Occupants of wildlife ponds need shade and privacy and it is suggested that two-thirds of the surface is covered with vegetation. The big leaves of deep-water plants are both aesthetic and functional. Amphibians need sites for egg laying – newts put single eggs in rolled leaves. Some insects like to settle on tall reed-like plants, which provide visual contrast. Shade also deprives algae of solar energy.

Creatures hide from predators in marginal plants, within the pond and its surrounds.

PRACTICAL & AESTHETIC

Cluster single varieties of anchored plants in separate plastic latticed containers. Avoid rich soil and cover with pebbles to weigh them down. This way the algae are starved of nutrients; the plants are easier to rearrange and constrained from spreading – some native species are rampant. While frogs etc. are aesthetically insensitive, diverse planting will cater for a greater variety of species. Flamboyant colours are not for an allotment pond by a railway; the emphasis will be on shape, size, texture, repetition and green harmonies. In winter spent pond vegetation is unattractive but the appearance can be offset by a careful choice of plants in the surroundings. I plan to use grasses, sedges and winter flowering shrubs.

SHORT LIST OF USEFUL PLANTS H = hardy

Wm Robinson’s classic “The Wild Garden” (1870) makes strikingly similar suggestions to his modern namesake Peter (2000).

1. OXYGENATORS F= floating; A = anchored

   Botanical	Folk	Depth	Comments
   Callitriche sp.	Starwort		FH.Stems to 50cm long. Refuge
   Ceratophyllum sp.	Hornwort		FH Mats to 60cm. Cold shade
   Hottonia palustris	Water violet	<20cm	AH Flowers on tall spikes
   Hydrocotyle vulg.	Marsh pennyw’t	<30cm	AH Masks pond edges
   Myriophyllum aqua.	Parrot’s feather		FH Pretty thug aka milfoil. Cull!
   Ranunculus sp.	W.crowfoot	c35cm	AH White buttercups, nice leaves

2. FLOATING NON-OXYGENATORS

   Botanical	Folk	Depth	Comments
   Hydrocharis sp.	Frogbit		H Like tiny w.lily. Shiny leaves in rosette
   Lemna minor	Duckweed		H Invasive shade-giving food
   Stratiodes aloides	W.soldier	<1m	H Like pineapple tops. Sinks in cold

3. DEEP WATER PLANTS

   Botanical	Folk	Depth	Comments
   Aponogeton distachyos	W. hawthorn	60cm	Big, shade tolerant, scented flowers
   Nuphar lutea	Yel pond lily	45cm	Small flower bowl over big leaf
   Nymphoides peltata	Fringe lily	<45cm	Prolific autumn flowers. Spreads
   Nymphaea sp.	Water lily	vary	H Native var. is white & invasive
   Orontium aquaticum	Golden Club	<45cm	H Gold poker tips, lance leaves

   There are numerous alien decorative water-lily cultivars, some tender – seek advice.

   Nelumbo species (lotus) are all tender.

4. MARGINALS

   Botanical	Folk	Depth	Comments
   Acorus calamus	Sweet flag	20cm	H Tall, narrow leaves. Wildlife cover
   Alisma pl-aqua	W. plantain	15cm	H Tall, delicate. Seeds are wildlife food
   Butomus umbel.	Flow’ng. rush	10cm	H Tall elegant pink fl. Typha partner
   Caltha palustris	M. marigold	15cm	H Edge cover. Spring waxy flowers
   Carex sp.	Sedges	min	H Arching stems in winter. + surrounds
   Equisetum fluv.	Band’d H’tail	20cm	H Tall e-green invasive rush, brown rings.
   Eriophorum ang.	Cotton grass	5cm	H . Dies in deeper water. Cotton buds
   Iris pseudacorus	Yellow flag	25cm	H Vigorous wildlife shelter
   Juncus sp.	Rush	10cm	H Flowers are brown drumheads
   Mentha cervina	Spearmint	5cm	H Superbly aromatic. Blue flowers
   Mentha aquatica	Water mint	20cm	H Hairy lvs, clover flwrs for bees
   Menyanthes trif.	Bog bean	5cm	H Sets of wispy pink flowers on spikes
   Mimulus guttat.	Monkey musk	min	Just H. Sum. aerial roots, profuse yell. fl.
   Myosotis scorp.	Forgetmenot	8cm	H Habit, leaf, blue flowers – perfection
   Pontedaria cord.	Pickerel we’d	12cm	H Robust, tidy, decorative blue flowers
   Ranunc. lingua	Gtr spearwort	20cm	H Sappy red stems, yell fl. Blows over.
   Rumex hydro.	Gt W dock	min	H Fl.6ft. 3ft lance leaves bright red in aut.
   Sagittaria ditto	Arrowhead	15cm	Just H. Tall. White fl. Ducks eat tubers
   Typha minima	Reedmace	10cm	H Bigger sp. invasive & puncture linings
   Veronica becca.	Brooklime	8cm	H Creeping, dark blue flowers. Mud OK
   Zantedeschia ae.	Arum lily	min	H at 30cm in win. White fl. in spathes

SUPPLIERS

Nurseries and garden centres advertising aquatics cater mainly for big-spending fish-keepers. The fifteen serious nurseries specialising in aquatic plants listed in the RHS Plantfinder guide are all far distant from Coventry. We dealt with a small mail-order firm Puddle Plants in Suffolk. Their useful website www.puddleplants.co.uk lists over 100 species by depth and function, gives botanical and folk names and highlights native species. In spring they have off-the-peg collections for various purposes. We paid about £85 for the large native pond collection of 50 plants plus containers, including delivery. They were willing to amend the package to meet specific requests. Wilkinsons sell aquatic containers cheaply. Supplemented by local purchases, transfers from our garden pond and by gifts from friends, the final tally exceeded 100 plants (including many repetitions) for a 10 square metre pond.

WILDLIFE

Once plants are in, a new pond will be colonised from the bottom of the food chain upwards starting with micro-organisms and algae. Birds stop by to drink and bathe, especially if you place flat rocks at water level and branches just above it. Larger and larger invertebrates arrive on birds’ feet or from eggs hidden in plants. There will be whirligigs, pond-skaters and water boatmen. Flying insects arrive on the wing. Amphibians will find ponds themselves, as will mice, hedgehogs and foxes. With less than a quarter of the surface covered, early unwelcome visitors were a pair of mallards, who threatened to eat the new plants. They enjoyed being chased and shouted at, but took fright at a rake. They gave up once the pond had little open surface left. By the summer there will be butterflies and dragonflies. Butterflies are strongly attracted by the dull red colour of the bridge across our pond, and like the surrounding grasses.

The most welcome visitors are frogs, toads and hedgehogs - nocturnal slug eaters all.

Frogs and toads spend scant time in ponds outside the breeding season and it is vital to have hiding and hibernating spots nearby. When a dangerous dying tree was felled by our plot we took many logs to stack near the pond as a refuge for beetles and amphibians. There are also piles of large stones. Such is the attrition of young frogs and toads that several thousand eggs are laid with the prospect of one yielding an adult. They live for 10-12 years but do not reach sexual maturity until age 4–5. Putting in frog spawn annually from a healthy established pond is good, but it may take several years to establish a sizeable colony. Newts are so charming that they can be forgiven for eating frogspawn – there should be enough to go round. Palmate and crested newts are scarce protected species. Hedgehogs are unbelievably stupid and slow. They eat slugs only because they cannot catch anything else. There are many reported cases of hedgehogs falling into ponds and drowning because they cannot get out again. Protect them by having a shallow beach at one end of the pond and a gently sloping ramp to the surface on a deepwater side of the pond.

There has been a notable increase in birdsong to accompany our work on the allotment, from various passerines not just robins, blackbirds and pigeons.

Fish are bad for wildlife ponds; they eat useful pond contents, defecate endlessly and upset the ecosystem. The same is true of the great pond snail, though scavenging ramshorn snails (from aquarium suppliers) hoover up algae and plant debris.

References

 

This is a personal list of my own books that I consulted; it is not comprehensive. The most useful is 13) which I unfortunately found in the remainder shop in Hertford St after I made my pond. I am too old to benefit, but have just learned from 7) that the Elizabethans used the seeds of white water-lilies both to cure baldness and to suppress carnal appetites.

1. Chinery Michael, Insects of Britain and Western Europe, Collins, 1986. 2300 splendid scientific paintings complement the helpful text.
2. Frazer Deryk, Reptiles and Amphibians in Britain, Collins, 1983. Detailed scientific account of fieldwork for the general reader.
3. Hamilton Geoff, The Organic Gardening Book, Dorling Kindersley, 1987. Organic pioneer tempered by practical experience. Butyl rubber fan.
4. HDRA, Encyclopedia of Organic Gardening, Dorling Kindersley, 2001. Earnest and worthy committee manifesto with no jokes. Excellent section on planting for wildlife, but thin on pond practicalities.
5. Mabey Richard, Flora Britannica, Sinclair-Stevenson, 1996. Entertaining and comprehensive folkloric and historical account of wild plants.
6. McClintock David and Fitter R, Pocket Guide to Wild Flowers, Collins, 1955 on. Superb novice’s guide to botanical details and habitat. Well organised. 600 colour and 700 b/w illustrations. Cross-indexing of botanical and folk names.
7. Phillips Roger, Wild Flowers of Britain, Pan Books, 1977. Fine photographer’s record in large format, by chronological order of flowering.
8. Phillips Roger, Grasses, Ferns, Mosses & Lichens of Great Britain and Ireland, Pan Books, 1980. Extension of 7). Inc. sedges and rushes. Valiant effort to make them interesting.
9. Prime C, Plant Life, Collins, 1977. Organised by GB habitat in a readable textbook style. Good on natural ponds.
10. RHS, Gardening through the Year, Dorling Kindersley, 2001. Colourful prompts for tasks, like pond maintenance, you really shouldn’t postpone.
11. RHS, New Encyclopedia of Plants and Flowers 3^rd ed., Dorling Kindersley, 1999. The bible. Has section on water plants.
12. RHS, Plant Finder, Dorling Kindersley, annual. Has become standard listing of cultivated plants as well as guide to suppliers.
13. Robinson Peter, The Practical Rock and Water Garden, Hermes House, 2000-06. Magnificent! Tremendous scope, excellent illustrations.
14. Robinson William, The Wild Garden, Century Publishing, 1983 (original 1870). Intro by Mabey. Historical attack on regimentation in gardens, packed with advice.
15. Sandars Edmund, A Beast Book for the Pocket, OUP, 1937. A zoologically precise gem, written by an idiosyncratic iconoclast who does for wild and domestic animals (including man) what Fowler did for English usage.
16. Thomas Graham Stuart, Colour in the Winter Garden, Orion, 1957. A classic. Helpful for pond surrounds.

Google searches on the internet generate huge numbers of limited websites, some from respectable sources such as the RHS and the Wildlife Trusts. There used to be one describing the disastrous and expensive attempt by Monty Don to clay line a large pool for Gardeners’ World, but I cannot find it now!