Choosing Rock, Stone and Gravel for Your Pond

Picking the right type of rock for your pond – and then using it imaginatively once you’ve made your selection – can make such a difference to the overall look and feel of that whole section of the garden. When it comes to the garden pond – and especially one in a small garden – any old stone you find definitely won’t do, at least not if you want a really attractive end result.

Choosing the right pond stones to blend in

One of the most important things to consider when selecting rock and gravel for the pond is how it will fit in with the rest of the garden. Unless your water feature is located in its own little setting and hidden away so you don’t see any of the rest of your plot, you’ll need to take any existing rockeries, scree gardens, gravel paths and so on into account.

In nature, the rocks in any given area tends to be the same; although you will sometimes find a wildly unexpected stone in an unusual area – perhaps dragged there by retreating glaciers – by and large, if an area is limestone, it’s limestone and that’s all there is to it.

Pond Gravel to buy:

The upshot of this is that although there is always a little variation in colour, all the stones tend to be similar harmonious shades. For some types of formal or architectural ponds, deliberately manipulating colours to make a striking contrast can work very well – if that’s to your taste and what you were after all along. If not, the effect can be rather jarring. Install a blue slate cascade alongside a Cotswold gold path, for instance, and the look will certainly be striking – but it won’t look very natural.

Pond Stones to buy:

What size pond stones do I need?

Again, it depends on what you’re trying to achieve.

For a very artificial, structured look, cut slabs or matched pieces will give any rock-work a very controlled and architectural feel, while if a more natural appearance is wanted, a mix of sizes will work best. A lot obviously largely depends on the size of your garden – there’s no point in getting things hopelessly out of scale.

As a general rule, if you’re going for a natural look, pick some rocks which are as big as you can realistically get away with – ideally something which looks too big to have got there by itself. This avoids one of the most common mistakes of rockeries and rock features – looking like someone just emptied out a barrow of rubble, or worse still, what many books call the ‘dog’s grave’.

Shape and smoothness of pond stones

The shape and smoothness of rock, stone or gravel needed depends on the intended use. Mostly it’s common sense: overly smooth stones used for pond edging may be dangerous when wet, while rough or jagged ones used within the pond – or left in a position where they’re likely to fall into it – could damage the liner and so on.

Some kinds of features have particular needs. For bubble fountains, smooth, river-washed cobbles are the best choice – avoiding anything which is much under an inch (25mm) across to get the right ‘splash’. If you’re looking to fill the bottom of a cascade pool or small artificial stream, however, smaller sizes of gravel are usually called for, since they take up less space and algae tends to grow less well on them than larger pebbles. It’s a good idea not to go too small, though, especially if your water flow is a bit swift, or you may find they wash out too easily.

Sourcing your pond rocks and stones

Most garden centres and pond specialists – and even some of the larger pet shops – either have supplies of suitable rock or can point you in the right direction to find some. It’s often worth spending the extra to get rock that is specifically intended for the purpose, to avoid the possibility of anything leaching out of the rock and harming your fish or plants. Generally granite, sandstone and slate are good, safe choices, while limestone can alter the pH of the water, so along with the likes of concrete and reconstituted stone, it’s probably best avoided.

Wherever you get your rock and gravel from, it’s essential to give it a thorough washing before use, especially if it’s destined to be used within the pond itself, to remove any potential contaminants which might be harmful to your pond.

Rocks and water features are natural partners; well done, they complement each other perfectly, so it’s definitely worth the effort to make sure you pick the best sort – whatever the final effect that you’re hoping to achieve.

Further information

When working on the designing part of a pond, it is imperative to decide what edging would be suitable and how it will benefit your pond. Pond edging gives a pond neat finish and helps it appear more natural. It helps in blending the pond with its surroundings and does not make it look like a quickly added feature. There are many options available for pond edging but here we will talk about pond stones, which are one of the most common ways of giving a seamless finish to your pond.

Placing the pond stones and safety

Selecting and placing the stones matters the most as it should give the pond an aesthetic look and help in elevating its presence. Stones are not always easy to change after some period of time, as it will be time consuming and if the stones are heavy it will also take a lot of strength. Therefore, it is important to lay out the options that you can work with and then select the best one which suits your pond in the long run. To better adjust the stones in their place, it is highly recommended to build a concrete collar or similar which prevents the stones from falling in the pond. When selecting the size of the stones, make sure that you don’t go for big heavy stones for a small sized pond as it won’t look good and will steal the attraction from the pond itself. If you are picky, then select the colour of the stones yourself keeping in mind that stones do change their colour in the sun, as with time the colour fades away. Natural rocks also help in the growth of moss which adds an organic touch, making the pond look effortlessly attractive. Another option to play around with are how you position the stones (which are like pieces of a puzzle and look great if they are joined with their right pieces!) As these are big stones, you may need a tripod hoist to keep them in their place and whilst working with these stones, be careful so you don’t crush your toes. Gloves and protective footwear are a must when you are working with such stones.

What rocks are best for ponds?

It is important to use smooth or rounded stones in ponds to prevent injury to fish. Granite, sandstone, and slate are the best types of rock to use. Many stones are beneficial for fish and wildlife, but certain stones such as marble or limestone are not suitable for ponds as they can cause excess alkaline in the water. However, there are many fish-friendly decorative aggregates, cobbles, and stones suitable for ponds.

Do you need rocks at the bottom of a pond?

Yes, rocks and gravel are essential for the bottom of a pond as they provide a habitat for beneficial bacteria. These bacteria break down muck that would otherwise build up on the bottom of the pond. Rocks and gravel also protect the pond liner from sunlight.

Should you put anything in the bottom of a pond?

Pebbles are an excellent addition to the bottom of a pond as they provide hiding places for fish and anchor down plant life. Pebbles can also create the best kinds of habitats for all kinds of fish by giving them places to hide and rest.

Should I put sand or gravel in my pond?

Both sand and gravel are suitable for use in ponds, but it depends on personal preference. Sand is heavy enough to hold the liner down and prevent floating, even when gas is produced, as long as you add at least three to four inches. Gravel provides a habitat for beneficial bacteria.

What is the best gravel around a pond?

Pea gravel is the most commonly used and recommended type of gravel for use in koi ponds.

How many rocks do I need for my pond?

The quantity of boulders needed for a pond depends on its length and width. A rule of thumb is to measure the surface area in square feet and use the formula: Quantity of rocks (tonness) = length (ft) x width (ft) divided by around 65.