It’s different from a basic fish pond, because a natural pond will tend to attract more insects, dragonflies and birds… Three square yards or meters are all you need to create a little oasis of biodiversity. Both useful and ornamental, the natural pond will bring you many advantages.
Here is how to set up a natural pond.
Preferably in a dry, flat space, in the lowest-lying portion of the land. There shouldn’t be too many overhanging trees around it or falling leaves would rot in the water.
Also avoid places that get too much sun and would get too warm, because water would evaporate too fast.
Think ahead as to where you’ll use the earth you’re digging out. Will you stack it along the side of the pond, or add it to a square-foot vegetable patch? Mark the banks of the pond by using a string attached to twigs in the ground to form its curves. Use a bubble level or a transparent water hose to check that the banks of the pond are level.
What is best it to dig the pond out in layers: first, dig about 1 ½ feet (40 cm) off the entire surface, then offset towards the inside by another 1 ½ feet (40 cm), thus making the sides look like a large curvy staircase. Continue until you reach a depth of 32 to 48 inches (80 to 120 cm). Rent a small excavator if need be. This portion will never freeze over winter and won’t dry up in summer, either. Along the northern-most bank, break the staircase into a smooth inclined plane.
Use a measure of black PVC plastic (1 to 2 mm thick) of the following size: width of the pond plus twice its depth and an additional 12 inches (30 cm) to each side. Pull out roots and sharp rocks, and layer about 2 inches (5 cm) of moist sand along the bottom.
Spread horticultural fleece along the bottom, and then shape your plastic tarp. Use stones along the edges at the top to hold it in place. Final anchoring will only be prepared once the pond is filled. Again, layer about 2 inches (5 cm) of sand and clay along the inside of the plastic tarp. Aquatic plants will spread their roots in it. Avoid soil mix.
Ideally, wait for rainwater to fill most of the pond up. Top-up eventually with water from a nearby well. Tap water, often expensive and chlorinated, isn’t much recommended, but if it’s all you’ve got it’s still fine.
Forget about exotic plants if you don’t live in warm areas. Without a doubt, what’s best is to roam around the nearby countryside and collect one or two specimens from plants you find along river banks or ponds: forget-me-nots, cattails, water mint… There are semi-aquatic plants like water iris or reeds, floating aquatic plants like lentils, water lilies and submerged plants like watermilfoil or elodea waterweeds. Transplant them to your pond, before June ends, in a pot that is weighted down with a stone.
Along the inclined plane, keep a small beach without any plants so that birds can come drink. Frogs and dragonflies will appear on their own to populate this little natural park!
In fall, cut the plants along the banks and pull out submerged plants that have spread out too much. Before discarding them away, lay them for a for a few days on the waterbank for any little critters that inhabit them to crawl back to the pond for safety.
After a few years, remove about half the silt that builds up along the bottom. This protects the pond from loosing too much oxygen because of decomposing matter.
By C. Levesque
