Easy Ways to Cover a Pond Bottom and Edges

Garden pond stones for edging and bottom are often an afterthought.

Stones are a reality for garden ponds because liners are a reality.  Your EPDM or PVC liner is an eyesore, and wherever it shows, it basically says to the world:  “This pond is fake.”  Stones are the preferred pond-builders’ way to cover up liners.  After all, there is a reason why “rocking” is a verb for pond makers.

But using the wrong garden pond stones or too many stones can have dire effects.  At the very least, they won’t adequately cover up the liner; at worst, they can pierce the liner.  Somewhere in the middle of the pain spectrum are things like:  rocks that are difficult to clean; rocks that are easily carried by water movements or gravity; or rocks that don’t look like they belong with a pond.

Here are the best stones to use for your garden pool, in two major cover-up zones:  bottom and edges.

Pond Bottom:  Small and Mighty

The pond bottom is the largest area to cover, so you need stones that are smaller, cheaper, and available in great quantity.  For a sizable pond, buying a cubic yard or half-yard from your local garden store or stoneyard is not a bad idea.  But if you can handle the idea of higher prices and multiple runs, you can also buy bagged stones at your local Home Depot or other home improvement store.

• Pea Pebbles: Pea pebbles are, amazingly enough, about the size of green peas.  Ranging in size from 1/8″ to 3/8″ diameter, pea pebbles are big enough to avoid getting sucked up into the pond pump (though this may still happen with very powerful pumps, in which case you’ll want to create a zone around the pump that is free of stones).  Because pea pebbles are smooth, they will not puncture your liner. If you have any kind of slope on your bottom, though, pea pebbles will glacially side downward.  Pea pebbles make it easier to clean off the big debris from your pond bottom, because they do not have nooks and crannies that will hide that debris.  But they make spraying down your pond bottom difficult because they want to slide.
• Landscaping Stone (1″ to 2″, Polished): I like these larger stones better than pea pebbles because they stay put and are more visually noticeable.  As alluded to earlier, the larger your garden pond stones, the more opportunities they present to hide junk that you need to remove–leaves, needles, pine cones, etc.
• Black Mexican Beach Pebbles (1″ to 2″): Unimpressive dry, these largish and lightly textured stones (but still smooth enough for your liner) turn jet black when submerged.  At the bottom of a deep pond, they will disappear.  If creating a visual illusion of depth is your goal, you can use these in the deeper areas.  In shallow areas (3″ to 6″), they show up and look fantastic.

Pond Edges:  Flat and Functional

Edging garden ponds with stones is a contentious topic.  If I earlier said that a visible liner makes a pond look fake, that telltale ring of rocks encircling a garden pond comes as a close second in terms of fake-signalling.  Jeff Rugg in Pond Trade Magazine rightly talks about “leaving the old style rock pit behind.”  Too many ponds use too many rocks.

On the other hand, rocking the very edge of the pond allows you to fit in more pond in less space.  It’s a crisp border.  Real ponds’ edges, if they aren’t slushy, swampy mud-traps, are gradually sloping beaches of sand, pebbles, and rock–you don’t have space for that kind of broad transition.  So a rock edge it is, at least at the beginning of your pond’s life.

• Flagstones:  These large and flat stones cover maximum space with very little movement.  You can even overhang them a few inches over the pond to further disguise the pond walls.
• Retaining Wall Blocks:  Obviously these will not give you a natural appearance.  These are for creating the look of manmade curves around a pond.  One advantage is that, since they are so heavy, they do a great job of holding down the pond liner edges.  Also, because they are angled, they can easily form curves.

Garden Pond Stones to Never Use or Use Only Sparingly

To avoid piercing the liner, avoid using garden pond stones around the bottom such as lava, crushed gravel, bluestone gravel, granite chips, white marble chips.

Not great for pond edges:  ledgestones, river rocks.  You can use them here and there for effect, but rocking an entire perimeter with them would crowd out the pond itself.

Entirely avoid using manufactured stone veneer for edges and bottoms.