More pond myths

Five standard pieces of advice about garden ponds from a well-known garden wildlife website. Most are either wrong, misleading or only partly true.

Make your pond as big as possible – this is better for wildlife as there will be more habitats.

This is one of the oldest myths about ponds. The ‘bigger the better’ myth. To double the number of species of animals you see in a pond you have to increase its area roughly ten times. Put another way, the difference between a 2 metre square pond and a 4 metre square pond is negligible in terms of species variety.

To double the number of species found in a 2 square metre pond you have to make it 20 m square. So before worrying about the size there are several other things you can do to maximise the diversity of your pond: make sure the water’s really clean; provide plenty of very shallow water; encourage a wide variety of plants; make sure there are leaves and fallen wood in the water. 

Put it somewhere sunny, away from trees. Ensure some edges are shallow and sloping to allow animals easy access. 

As regular readers will know, my pond is quite shaded and right next to a tall hedge: I noticed yesterday about 1/4 of the pond was in full sun at mid-afternoon. My pond is fine! Full of taddies, thousands of mayflies, backswimmers, newly arrived caddis flies, breeding dragonflies and damselflies, water beetles, naturally colonised water snails.

Having shallow edges is important – even more than this advice implies. Shallow water – very shallow – is crucial in a really good wildlife pond but its tricky to organise. Standard pond designs with their 12 inch deep shelves have virtually no shallow water. 

Stock your pond with native plants from other garden ponds or garden centres. Never take plants from the wild. 

You can stock your pond but I would always get plants from the local wild. Another garden pond is OK if you know your plants, but the chances of getting non-native undesirables is much higher from garden ponds, where these plants are commonest. But isn’t taking plants from the wild wrong? For some specially protected species it is always illegal. For common plants, you need the landowner’s permission, but there is nothing wrong with this. Moving a small quantity of a common plant a short distance (say 1 km) is very unlikely to do any harm. This is how plants spread naturally: carried by birds, grazing mammals, wind and floods moving seeds or small pieces of the plant around naturally.

Far more harm has been done by people buying plants from garden centres which have turned out to be undesirable. If you want to buy plants, check that they fulfil this local provenance rule. And remember, conservation bodies are often pulling water plants out of ponds and wetlands as part of  perfectly sensible conservation work! But never take plants from you local nature reserve (unless they’ve already been pulled out by someone as part of the reserve management plan): a nature reserve is a place where there’s a danger of pulling up something rare or protected – outside of nature reserves this danger is much smaller.

As far as I know, a bit of picking never hurt any of Britain’s water plants: water pollution, draining wetland and filling in ponds have put paid to them.  

Insects, amphibians and invertebrates will find your pond surprisingly quickly on their own. 

Yes – a bullseye! Freshwater plants and animals have the most amazing ability to find little patches of new water – and so they should because they’ve had millions of year’s of practice! So you don’t need to add a bucket of sludge to get your pond started. All this does is means that you miss out on the ‘wow – they colonised my pond’ factor.

Don’t include goldfish; they eat frog and toad spawn. 

The ‘don’t include goldfish’ advice is complicated. Common Toads co-exist with fish – they prefer fish ponds – so there’s no reason to think that their spawn will be eaten by fish. Frogs spawn can develop in larger ponds with fish, provided there is some cover – but if there isn’t shallow water and dense cover for the common frog taddies they will be gobbled up. Toad tadpoles are distasteful to fish: they live with them happily.

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