Dig an informal wildlife pond working from the outside area to the inside
1. Edging shelf and shelf plants
- Mark out the pond and hard landscaping outside rim with a hose/string or a run of dry sand
- Dig the first shelf area to contain the rocks/cobbles or other edging materials and rafting plants
- The inside shape of this shelf does not need to match the outside shape of the pond but must be flat.
- Shelf should be wide enough for a width of stones near the pond edge and some plants on the water side of the shelf
- Some part of this shelf can be made as a sloping beach edge up to the garden level for hedgehogs. Here the internal shelf needs to be wider as after being flat to start with it will taper gradually back to the garden.
- Place larger stones on the flat shelf and bank smaller cobbles/stones against these so they do not roll down
- The depth of this shelf should be in proportion to your pond size: 6-13cm (3-5") deep for a small pond using cobbles or 14- 20cm(6-9") deep for rocks or stones.
- The rocks or cobbles used for your edging will sit on the outside rim of this top shelf within the linered area. Water level will be approx half way up your hard landscaping materials so they protrude above the water..
- Include this shelf area when calculating your liner requirements. Add the full upright height above the shelf to garden level as this will form the vertical upstand to contain the water
- Rafting (horizontally growing) shelf pond plants placed with the cobbles or rocks of this shelf will blend the pond edge into the surrounding garden and give a method of escape for the wildlife.
- Finish the liner in a vertical plane trapped upright by the rocks or cobbles against the outside rim of lawn, patio or pathway materials so the pond lip is not exposed.
- Historically, pond liners have been laid to finish horizontally - you would always see the rounded lip of the pond edge as water could never fill over and hide it. This looks unsightly and allows sunlight to make this rounded lip vulnerable to cracking through UV exposure.
2. Shelf plant shelf
- Dig the whole remaining pond area to the flat depth of the next shelf at 14-22cm(6-9") below finished water depth - shelf .
- Dig down sharply to give an upright edge to each level. Internal sloping areas cannot hold plants - they will slide down the slope to the shelf below
- Cut across the curves to give wide spaces of shelf into the corners. Try not to build a thin rim of shelves around a larger surface area of deeper water
- Make each flat shelf as wide as possible so you can use groups of aquatic plants together rather than have them lined up around the water rim like a parade of soldiers
3. Shelf plant shelf
Then mark out and dig the flat areas that you intend to be deeper - the next shelf depth of 23-44cm(10-17") below finished water depth - shelf . There are not many upright plants and no rafting plants suitable for this shelf. Plant waterlilies.
4. Shelf plant shelf
Finally mark out and dig the deepest section of the pond - 60-75cm deep(2ft-2ft 6") - shelf
With this plan you do not disturb the compacted soil which will make for firm shelves but stay off the edge of each shelf as you dig the next so you do not collapse it.
The image shows a Pond Profile - the construction under the liner that gives the levels and shape to your pond.