How to build a miniature wildlife pond to suit any garden 

Mini ponds offer a quick, inexpensive means to create a water feature, even on a balcony. We get expert advice

Kya deLongchamps's pond after a bit of refreshing. Birds and hedgehogs can forage in the dry and moist areas around a pond like this, as well as using it for rehydration and bathing. Picture: Kya deLongchamps

Frances Gallagher of Rinn Bearna Aquatics is a wise wild-water keeper. She had told me in May of 2020, that it would take probably two years to establish a small water body attractive to frogs. But no. I trudged down to my tiny wildlife pond in March, and took a flat equestrian dung fork to sieve out the debris from what my nose read as rancid, stinking water.

The marginal flora was doing well, rich in bluebells, violets and various self-seeding native plants. Still, with no sign of amphibians, I folded to horticultural expectations instead of giving nature its patient due.

Full of leathery, disintegrating leaves, and with the feeble solar fountain clogged with weed, surely this pathetic puddle was a place of death and drowned, sustainable adventure.

Having roughly flipped about 5kgs of sludgy autumn leavings to the shore, I levered the tines out of oily, opaque water and froze. Something was struggling violently under the load suspended in the air. With a tender gloved hand, I lifted out a very large, glistening frog. 

An idiotic eco-thug, I had vandalised a perfectly functioning, native environment in just a few minutes. Each leaf and twig from my aquatic nursery was tenderly rinsed, and we returned dozens of tadpoles the size of tea leaves to the reeking depths.

CLIMATE & SUSTAINABILITY HUB

Elated, we warmed well water, and poured several buckets over a rock, at a trickle. I added some clay pipes for underwater basking and contrite, and parboiled the lads a little broccoli. There was a peaty divot nearby, so we chanced a few jugs of that for biological enrichment.

Sucking and blowing out the filter re-ignited the fountain (only use a tiny one or you’ll suck up Hewy and Dewy). I propped up the solar panel in the calendula fringing the area, and it started its plucky, skyward spit. Within a few days, the water was relatively clear with mechanical oxygenation and I removed it, the tadpoles now posturing in shifting sunbeams. They know everything. I have a lot to learn.

Frances encouraged me to approach a planned pond extension very cautiously. “Plastic liners generally don’t have that long a life expectancy, and yours may well be past it,” she explained. “However, I wonder about keeping the small stinky pond going beside any new shiny metres — at least for now. It will remain a habitat, and the froglings will probably adopt the new side fairly quickly when they start hopping.

Gobnait Ni Neill of the Drimnagh Community Environmental Group leads a mini pond-making session Dublin. Picture: Tristan Hutchinson

There’s no telling about the adults. They may prefer the swamp with long-lived insect larvae and other dentin’s in those murky depths.”

Establishing a mini-pond

A metre square of ground, a bucket on the patio or a half barrel of 60cm depth sunk in the ground — there’s nothing really too tiny to accommodate the diversity of a wildlife water-feature. Gobnait Ni Neill guides the Drimnagh Community Environmental Group in Dublin, and is passionate about gardening that benefits biodiversity. “I love ponds,” she says.

“They really punch above their weight in terms of their size and the effort it takes to build one. There’s almost no creature that doesn’t benefit from a reliable freshwater source. I’ve yet to meet anyone who doesn’t stop to have a little look into a pond as they’re passing.”

Mini ponds offer a quick, inexpensive means to get a wildlife pond up in a weekend even on a balcony. Gobnait explains, “There are lots of common household objects that make great ponds. I’ve seen people use anything from Belfast sinks to biscuit tins. 

The ideal pond container is anything that’s watertight, and relatively sturdy, with no sharp edges. We recently discovered an almost endless free supply of these in the form of supermarket flower buckets (a handy size and shape, thrown away on a daily basis). We’ve just run a few events with Collie Ennis where we demonstrated how to build a mini pond and gave everyone a flower bucket and pond plant to bring home. If you’re renting your home, ponds are still very effective. Instead of sinking them down — build a surround for them using anything from potted plants, stones, bricks, twigs or logs.

Examining oxygenating plants that will keep the water clear in any nutrient-dense waterscape for amphibian mini beasts. Plan to plant up to about a third of the water's surface. 

Style it whatever way you like, as long as there’s perches and ramps for insects and animals to climb safely in and out of the water, they’ll be delighted.”

What else do we need to know? “Rainwater is the best,” Gobnait argues, “because the chemical treatments in tap water aren’t great for wildlife. If you have a water-butt, that’s perfect. If not, leave a few containers of tap water outside for a day or two, and most of those treatments will evaporate. If you’re aiming to support wildlife then fish should be left out.

“The pond is providing a source of drinking water for all sorts of thirsty creatures, from bees to passing hedgehogs. More importantly, it will also be home to lots of aquatic insects, like hoverflies, which in turn provide food for birds and even bats. If there were fish in the pond, they’d soon gobble all the insects.”

Frances adds, “The main problem re water quality is stuff falling in (mainly, leaves). Avoid overhanging poisonous foliage (laburnum, yew, rhododendron etc.), and plants with very big leaves such as

Water being examined at a mini-pond build day. Water from your rain barrel or bore-well is superior to mains tap water, which will take longer to develop friendly biology. Picture: Tristan Hutchinson

sycamore.”

Maintaining your pond

Wildlife ponds don’t require the attention of mechanical skimmers, UV clarifiers, anti-bacterial supplements, and vacuums. Watch out for overgrowth and the level of the water in general. Frances adds that even when you forget about the pond for a period, it can be saved.

“Frogs and tadpoles are pretty resilient and once you bring the water level up slowly with reasonably normal water, most of them will go back to growing, metamorphosing, and general tadpoling.”

Marsh marigolds, duckweed and blanket-weed can run amok if unchecked, excluding light from the water and gobbling all its natural resources. Spring and summer are a great time to consider new plants you would like to introduce (see our panel) and to cut back those getting out of hand. Frances argues that plants are preferable to mechanical oxygenation. “A little fountain doesn’t always improve things. Some plants and creatures don’t like water movement - water lilies, newts, and easily startled birds. It also increases evaporation quite a bit.”

Don’t wade in or rip out plants without consideration to creatures feeding and breeding. Around 25% plant removal is enough — don’t bald out the water surface as this will accelerate blooms of algae. Barley straw mats, available at good garden centres will cut back on clouding without the use of synthetic chemical algaecides. Plants that float on top of the water can mitigate light together with small trees introduced at the water’s edge. Gravel in a pond is a rich, nutrient-dense landscape for amphibian mini-beasts, and can run onto a shallow stony shore. Don’t get too drawn into the designer world of frog-caves and “mystery waterfalls” — examine what the animals really need.

Learn from my bungling. Leave your small pond alone once it’s filled, and happily oxygenating, and enjoy the sight of butterflies and dragonflies benefiting from a little spade-work. Finally, don’t forget that young children can drown in as little as 15cm of water. Log on to Water Safety Ireland, to see if that pond is for you, watersafety.ie. Thinking ahead? Develop the little landscape.

Adding hedging, plants and even a man-made miniature wetland — your pond can be the epicentre of a wider, wild habitat. Birds and hedgehogs can shelter and forage in the dry and moist areas around your pond, as well as using it for re-hydration and bathing.

Download full PDF instructions for your own mini-pond with words and photographs by Gobnait Ni Neill and Ken Duffy at the homepages of Drimnagh Community Environmental Group on Facebook.