Whether you’re installing a small residential water garden or a large commercial pond, the key to producing one that is both natural-looking and easy to plant is largely determined by how you design the excavation. So, before you dig, think about the plants, which are critical to the health of the pond’s ecosystem.
Building a top-notch pond that looks like Mother Nature created it herself, requires planning and excavating in such a way that you can accommodate the variety of aquatic plants at the various depths they require to thrive. If you wait to think about the plants until after the pond is installed, you’ve missed your chance to get things right.
This doesn’t mean you need to think ahead about individual plants and specific locations. Instead, think in terms of broad shelves that encompass the ideal water depths for the ranges of plants you want to include.
Pond Plant Requirements
Marginal pond plants typically require a water depth from one to twelve inches, depending on the type of plant. In general, however, we recommend setting a shelf at 10 inches to take care of most plants in this category.
Waterlilies thrive in between 12 and 36 inches of water. Hardy waterlilies planted in less than 12 inches of water may not make it through winter.
Oxygenators (including anacharis, hornwort,or cabomba) also prefer being planted in 12 inches to 36 inches of water.
The important point here is that different plants and plant types have different requirements. If you plan your pond excavation knowing what specific plants you want and the specific depths they require, carving out shelves for them is a straightforward proposition.
By altering depths in different areas, you create opportunities for both visual and biological variety within your ponds. And remember, just because you’ve set up a shelf doesn’t mean you need to plant it. The importance of planning, especially excavating with a plan, is that you’re giving yourself flexibility in your ultimate planting decisions.
As you map things out, remember that the width of the shelves is critical to determining how much space you have for plants. Think of these shelves the same way landscape designers think of foundation plantings around houses. If you design the planting bed to extend two feet away from the house, the selection of perennials, annuals, and shrubs will be severely restricted as they grow. But take that same planting strip and add some bends and curves that allow the bed to come out a few more feet in certain areas, and you have opened things up for a whole new range of plants which creates greater visual appeal.
Avoid Uniform Pond Shelves
The same basic principle holds true when you’re designing, excavating, and planting a pond. Unfortunately, most guidebooks on pond construction will demonstrate how it’s done with a kidney- or figure-eight-shaped pond with a strip of shelves that extend about 18 inches inside the edge. While such a design is adequate, it’s also a bit dull. The uniform shelves have a formal look and seem rather unnatural. What’s worse, they don’t allow for proper planting spaces.
Instead, try varying the shelf width. Consider increasing it to three feet along portions of the far side of the pond. This provides space for a wide variety of plants at the margin and will give you the option of setting up what looks like a wetland edge.
As you plan, always keep primary viewing locations in mind. Excavating a wide marginal shelf along the far side of the pond allows you to plant a dense selection of tall aquatic plants and create a natural-looking background. Then put a narrower shelf on the near side and plant it with shorter plants. This keeps the best viewing angles open.
Also, you might consider eliminating a portion of the near-side planting area altogether. Instead, create an edge where the pond meets up with a hardscape or formal viewing area. Providing a deeper section of plant-free water here will allow fish to come to the side of the pond and greet the owner for feeding. This is a great spot to add a large, flat boulder for sitting and dangling feet in the water.
Aquatic plants go a long way in beautifying a pond and tying it into its surrounding landscape. Not to mention, the addition of pond plants helps to control the algae population. So, before you start your next pond project, remember to consider how you want to add plant shelves before you dig!