A cheap, effective, and indestructible small wildlife pond.
1. The tank – available for about £70.00 from many agricultural suppliers 1.2m wide x 34cm deep. Tough, rigid, thick polythene. Cannot be punctured accidentally. Can I just stress that point. It cannot be punctured accidentally. This is crucially important! Even though your new pond will fill up with life in the first year, it takes several years for a full assembly of amphibians and other water-dependent species to develop in the surrounding land, and to suddenly puncture the pond and loose the water- source just as this is getting going is incredibly sad! I have seen many promising wildlife ponds fail this way in the past.
2. Because the tank is circular, with nearly vertical sides, it is extremely easy to dig an accurate hole for it. Make sure the bottom is level, and the sides are not collapsing, then drop the tank neatly into the hole. Put a bit of sand down the sides to fill any gaps.
3. Choose a sunny position, without overhanging trees. Heavy-leaf fall in the autumn is a problem in a little pond!
4. First, put about 40-50 kg of clay or loam in the bottom of the tank. Then buy about 6 or 7 bags of gravel. The cheapest 10mm shingle from a builder’s merchant will do. Wash each bag thoroughly, until water runs through it clear. Then put it all in the bottom of the tank to cover the clay.
5. Then fill with water. Let it stand for a couple of weeks. Then add your pond plants.
Here we have used watercress, greater spearwort, water mint, hornwort, Canadian pondweed, and water starwort.
The first 3 are emergent plants which rise above the surface to flower, the last 3 are fully aquatic submerged plants. The ones we have used are in aquatic baskets, but you can weight the stems with a bit of wire or lead and plant directly into the gravel.
All will grow rapidly, and you will soon need to cut them back.
It is important to cut and remove overgrown pond plants for 2 reasons: A. They will soon fill and choke the open water in a small pond. B. They take up the nutrients in the water, and removing them, you clean the water.
Let me explain: when you fill the pond with tap water, in a big city especially, you will find it rapidly goes green and soupy. This is because city tap water has been through the sewage works an average of 6 or 7 times before you get it. So, it is full of plant nutrients. Do not be tempted to change the water, or add any chemicals. Just let your new pond plants grow, and every time you cut them back, you are taking a load of those extra nutrients out of the system, and very soon the algae will die off. You can bypass this establishment stage by filling the pond with rainwater.
6. Don’t be tempted to plant tall plants all around. Leave the south-facing side more open.
7. Also, you can use the dug-out soil to create a crescent shaped “hill” or bank on the north side of the pool, facing south across the water. This will make a fantastic nesting bank for solitary bees. Keep an eye on the bare soil of the bank, and you will see little holes appear, with little trails of soil crumbs under them. These are the burrows of mining bees.
A bee bank behind a new pond.
But more about them in the next wildlife gardening article...
Adrena Fulva – the tawny mining bee. They dig their burrows in March. (Pic. – Wikipedia)
8. One of our own “tub ponds” at our wildflower nursery, 5 months after it was dug in.