There are several points you need to consider before building your pond: Should it be formal or informal, natural or modern? Do you want to keep fish, grow plants or attract wildlife? Are there children to keep safe?
Once you have answered these questions you need to decide where you want to site the pond or water feature bearing in mind the following: A pond should be kept away from big trees and shrubs so ensure their roots don’t puncture the lining and to avoid leaves falling into the water. If you want to keep fish you need to have a pretty deep pond to stop it freezing over the winter. The smallest you should build a pond is 60cm (2ft) deep and 1 x 1.5m (3 x 5ft) across; however, the bigger the better.
Now you can begin building:
- The easiest way to build a pond is to use a butyl rubber or plastic sheet. To work out how much to buy first dig your pond to the size and shape required then measure the length, width and the deepest point. Multiply the depth by two and add to the length then again to the width. Then add 50cm (20in) for overlap on both the length and the width. This is the size of sheet you need
- When digging the pond ensure that the bottom is firm and flat and free from stones. At least part of it needs to be 60cm (2ft) deep for fish and deep-water plants the rest can be 45cm (18ins) deep
- Build in some shelves around the sides 15cm (6ins) wide and 20cm (8ins) below the surface
- Slope one side to allow wildlife to escape
- Ensure that all pond sides are level by using a spirit level, don’t use your eye
- Spread 2.cm (1in) of soft sand over the base, shelves and slopes then cover with pond underlay followed by the liner
- Add a layer of poor garden or aquatic soil to the bottom of the hole for planing deep aquatics
- Start filling the pond from a hose or water butt
- Once full, trim the liner to 30cm (1ft) overlap
- Cover the overlap with paving stones or turf ensuring that the liner is not exposed to the sun as it will rot
- If possible add a bucket of water from a healthy, established pond to help speed up the colonization process
- Leave for about a week before planting and six weeks before introducing fish
- If you wish to attract wildlife to your garden then don’t add fish as they tend to eat the insect larvae
Looking after your Pond
Spring: most ponds will turn green in spring but it will clear itself in a few weeks. However, new ponds could remain green for up to twelve months. Pull out blanketweed and leave on the side for a day or so to allow creatures to escape back into the pond. Remove duckweed with a small fishing net.
Summer: Feed fish between May and September. Pull out oxygenators if they threaten to take over the entire pond.
Autumn: Remove excess silt from the bottom of the pond leaving about 1 inch to allow plants to root. Remove floating plants once the die, cut down marginals and pull out dead lily leaves. Keep autumn leaves out of the pond by covering with a net.
Winter: If you keep fish place a plastic ball on the surface to avoid the pond freezing over totally. If you don’t keep fish there is no winter maintenance required.