Put in a pond
If there’s one feature in the garden guaranteed to attract wildlife with astonishing speed, it’s a pond. And at a time when ponds have all but disappeared from farmland, it’s a hugely helpful thing to do.
The reason ponds develop so fast is that many of their animals (and even plants) are highly mobile. Within a short time your garden will attract birds, amphibians, insects, mammals and a host of mini-beasts you might never otherwise see. Even if you haven’t got room for a pond, or have young children, a small water feature (even a bird bath) makes a huge difference to the number and types of animals that will visit your garden.
Build a pond step-by-step
Choosing a site
You can build a pond any time of year, but it’ll establish fastest if you start in late winter. For most people it’ll take two or three weekends to complete.
Choose the sunniest site you can; dragonflies worship heat, and tadpoles wriggle over each other to reach warm shallows. Most water plants thrive in bright sunshine too. Try to avoid picking a place where autumn leaves collect, though it’s not the end of the world if you can’t (see section on maintenance below). More important is to hook up a pipe or hose so that your water butt overflow can auto-fill the pond during heavy rain.
Mark out your shape with a warm hosepipe, remembering that the finished article will look about two-thirds the size. The pond can butt up to a lawn, a border or a path, but make sure that at least one side slopes shallowly and that a fair chunk of the edge can be given over to dense waterside planting, and that this area in turn has a ‘corridor’ to borders, log piles, hedges or other sheltered areas. Come July, your emerging baby frogs will thank you.
Your objective is a deep area in the middle (two or three feet) for hibernating creatures, and a gently-sloping, shallow shoreline. Nearly every book tells you to dig this shape, but don’t do it! A gentle slope is very difficult to get level, and ensures you’ll be staring at an ugly black pond liner every time the water level falls (as it will) below the ideal.
Instead, dig the entire area straight down 12 inches. Try hard to cut cleanly with your spade, leaving the un-dug soil compacted; it’ll be easier later. Use the topsoil to make a raised bed or extend a terraced border.
Your job now is to dig a deep central hole, while leaving at least 18 inches (two feet is even better) undisturbed all the way round. Think of a gigantic, inverted fried egg. If you’re having a bog garden area, leave it 12 inches deep everywhere; it needs a flat base for its dam of bricks or stones.
Keep the subsoil on a piece of sheeting for later.
Fit the liner
Many books recommend butyl rubber for the liner but some experienced pond builders reckon the latest PVC is even stronger. Tell the supplier your pond’s maximum length and depth and they’ll calculate what you need (if you’re really thrifty you could find out what sizes the liner comes in, and dig your pond accordingly).
Choose a day with no wind, invite some friends round and get to work. It’s easy to cut the underlay with big scissors and fit it in the hole to protect against sharp stones. Next, open out the liner and drape it over the pond so that you’re certain there’ll be spare all the way round. Then add water, smoothing, pulling and folding the sheeting neatly as the level rises. Use a few rocks to subdue the bigger pleats. Try to keep the folds as simple as possible as they near the surface.
Sort the edges
Once the pond is full, cut off the excess liner at water level, leaving an extra foot (lying horizontally) all the way around. It’s a nerve-wracking job, so take your time, using a scalpel or a sharp knife.
With the excess removed, you can see how level (or not) the surrounding ground is. Ideally the water is pressing the liner outwards onto solid, compacted soil all the way round. If you have to build up any areas, make really sure you ram the soil down hard. If you don’t, it’ll settle later, and drain some of the water away.
Tricky bit over. From now on, it’s a piece of cake. Fill in the right-angled shelf all the way round with subsoil to create a gentle slope. It’ll make a hideous mess, but don’t worry. Add a little extra soil to hide the top of liner as you go.
By the time you’ve finished, you’ll find yourself staring at a muddy, unpromising wallow. Welcome to your new wildlife pond.
Wait for the sediment to settle a few days. If you’re getting plants from a friend, you can add them any time – even the scraggy bits left over after a hard winter. Otherwise, May is the ideal buying season.
You can be pretty slapdash about planting; your new charges will take off regardless. Floating plants such as hornwort, ivy-leaf duckweed and water soldier can simply be chucked in. For marginals such as water forget-me-not, brooklime, spearwort and water plantain, just use a rock or stone to hold the roots in contact with the subsoil. Only the big, pot-grown marginals need careful siting – usually in the bog garden section.
If you fancy a lily, pick a small one. Weight the rhizome down in a basket with some subsoil and lower it in, on ropes if necessary. That way you can haul it up and hack it back in a few years. Three things will now happen. The water will turn pea-soup green. The wildlife will begin to arrive. And then, almost overnight, the water will be crystal clear.
See the pond develop
The actual dig was in late January, and the first toads arrived in April. Now we’re in early May. The plants are in and the pea-soup colour is beginning to clear.
By early June the tadpoles are wriggling and the water crowfoot (top) is growing and flowering.
It’s now late August, and the young toads have developed and left the pond. The water soldier plants have multiplied furiously, and most will need removing before winter.
Keep your wildlife pond beautiful
As soon as you build it, your wildlife pond will start filling up with plant life. And it will do this with such enthusiasm that, if you ignored it for a decade or so, there would be nothing left beyond a damp hollow. This is a natural process known as ‘succession’, and if you let it carry on even longer you would eventually end up with a mature forest where your garden used to be.
To keep the kind of pond we all love – dragonflies, water beetles, newts and the rest – you need to ‘set back’ the process of succession over and over again.
So be brutal. When more than half the surface gets covered by plants, haul some of them out and sling them on the compost heap. Likewise if the underwater greenery gets too thick. It feels harsh, but in the long run you’ll be guaranteeing the pond’s future ability to sustain as many different species as possible.
Pulling out excess growth also helps keep algae down. When you first build a pond the water goes bright green. This ‘pea soup’ is a bloom of algae (their spores are everywhere) feeding frantically on the nitrogen in the water. Eventually these tiny plants use all the food up and fade away, leaving the stage set for your slower-starting pond plants. But they can always come back, especially as the well-known ‘blanket weed’, so the trick is to keep the nitrogen down to a minimum. And every time you remove green growth you’re doing just that.
Where does the nitrogen come from? Three main sources: tap water (hence our suggestion for a water butt overflow system – rain contains few nutrients); fish (a good reason not to have them in a wildlife pond); and decaying plant matter (which is why we use subsoil for the pond edges). Keep hoiking out the excess and you’ll have no trouble, year after year. And you’ll never need to ‘clean the pond out’ either.
Of course to yank out the plants you need to be able to reach all of the pond area safely. It helps if you can fix up some rocks or blocks on the edge at the build-up stage, so that you can throw a ladder or builder’s plank across the surface and reach in two or three times a year.
What about the creatures that come out with the plants? You may find you’ve just got to inspect each handful and pick out the beasties you treasure the most. Unfortunately, leaving a mass of plant material on the side ‘so they can escape back to the water’ does little good. Few creatures can worm their way out in time.
Lastly, there are the birds. You’ll find they all want to use a particular part of the pond to bathe, which is fine until their enthusiasm scrapes away the soil And exposes the liner. The best solution seems to be a big, flat rock (or two) just below the surface.
‘Surface’ is, of course, a movable concept where ponds are concerned. It’s quite natural for the water level to fall dramatically in summer, as evaporation and transpiration speed up. This is why a ‘right angled’ pond edge design is so useful. Where other shrinking ponds show yards of exposed liner, yours just reveals… more subsoil. Even your plants will adapt to the changing conditions, moving up and down the banks with the seasons. And when those summer rainstorms come, your water butt overflow refill system comes into its own.
A frog-friendly garden
So your pond’s up and running – what about the rest of the garden? Well, if you want your new amphibians to do well, you can help.
The trick is to think like a frog. By the time they creep out of the water in March, the poor things are utterly knackered. Some even die from exhaustion, which isn’t surprising when you consider they may not have eaten since the previous October. What they need is food and shelter. So ditch the chemicals (slugs poisoned by pellets are lethal), and encourage plenty of dense growth in your borders.
Best of all, start a log pile or three, using the biggest logs you can get. As summer warms up, the stable humidity and temperature inside the pile become a life saver for all sorts of beneficial creatures – not just amphibians but slug-slaying ground beetles and centipedes, and those arch recyclers of organic matter, the woodlice and earthworms.
Try to resist using cobbles and hard paving near a wildlife pond. Baby amphibians are incredibly delicate; on a hot day they’ll cook to death on such surfaces inside a minute.
Native pond plants
By all means grow some exotic water plants in your pond (as long as they’re not invasive – see ‘Ones to avoid’). But natives are pretty spectacular too, flowering from March to September. Any local wildlife gardener would be glad to give you their spares, but remember to be scrupulous about checking for invasive aquatic plants before you share plants from other ponds (see ‘Ones to avoid’). Alternatively, you can buy in spring from a specialist water nursery. Maintenance is dead easy: haul out anything that gets too vigorous in summer and chop dead growth back to ground level in early spring.
Yellow flag iris (Iris pseudacorus)
Scalpel-crisp leaves shoot up in May, followed by short-lived yellow blooms highly prized by bees
Marsh marigold (Caltha palustris)
Cheerful early green leaves and yellow flowers. I prefer the simple native form over the ‘Flore pleno’ double
Water plantain (Alisma plantago-aquatica)
Too-good-to-be-true green leaves are like ironed hostas – and that’s before the three foot fountains of white flowers in midsummer
Water forget-me-not (Myosotis scorpoides)
Blue flowers in summer, grows on the edges, so protecting young froglets from drying out
Brooklime (Veronica beccabunga)
Red stems, dark blue flowers, bright green leaves. Rambles freely, forming another humid shelter for young amphibians
Bogbean (Menyathes trifoliata)
Like a classy, overgrown broad bean with a springtime, pinky-white fuzz of nectar-bearing flowers
Ragged robin (Lychnis flos-cuculi)A classic plant of wet meadows: pink flowers dance in the May breeze
Greater spearwort (Ranunculus lingua)
Tall, emerging stems with yellow summer flowers: stairway to the skies for dragonfly nymphs, and food for bees
Flowering rush (Butomus umbellatus)
Sharp-edged rush with pink flowers. Grows under water or on the edge; also ideal for emerging dragons or damsels
Branched bur-reed (Sparganium erectum)
A zigzag rush with green flowers like giant burrs. The quintessential dragonfly perch
Purple loosestrife (Lythrum salicaria)
Tall, with dazzling pinky-purple flower spikes
Water soldier (Stratiotes aloides)
Freaky, spiky plant that floats and sinks as it sees fit. Needs deep water and lots of room; home for an immense range of amphibians, insects, snails, crustaceans and leeches
Water crowfoot (Ranunculus aquatilis)
Starts growing in late winter, so it’s good for toads to spawn around. Poached egg flowers. Very beautiful; needs its own space. Dies down by June
Hornwort (Ceratophyllum demersum)
No roots. Forms a dense underwater forest offering shelter, shade and oxygen to every living thing in the pond
Ivy leaf duckweed (Lemna trisulca)
Loosely-linked sinker/surface floater. Spreads fast, so keeps down algae and shelters baby animals
Water milfoil (Myriophyllum spicatum)
Not to be confused with the invasive red form in garden centres. A good oxygenator; newts like laying their eggs under the leaves
On the surface
Fringed lily (Nymphoides peltata)
Not really a lily, but gorgeous 50p-sized leaves look like it, and cover the surface to help keep down algae. Essential.
Ones to avoid
Water mint (Mentha aquatic)
Tough, invasive and strongly scented. Perhaps worth growing in a damp tub because insects love the nectar-filled flowers
Pond sedge (Carex acutiformis)
Attractive spiky leaves and black flowers. But sharp growing tips of underground stems can pierce pond liners
Canadian pondweed (Elodea canadensis)
Found in every fish shop and garden centre, but it can easily choke a pond and isn’t very beautiful