For the pond-building artist, stone is the paint—and how it is used can make or break the look of a water garden. Choosing the perfect stone, however, is no guarantee of a beautiful outcome.
That’s the realm where creativity and inspiration from Mother Nature as well as an understanding of stone’s characteristics, come into play.
To illustrate, let’s roll through some simple tips that will help beginners get started, and serve as good reminders for those with more experience.
Become a student of nature
Get away from your desk and head out into local parks and wilderness areas to find natural inspiration. Study the ways in which stone is arranged. Although stacking flat rocks on top of each other is undoubtedly the easiest way to build a waterfall, you’ll soon discover that it’s also the least natural—a dead giveaway that the waterfall is the work of unpracticed human hands.
When you examine natural watercourses, you’ll see that it’s much more common to find large, irregular chunks of stone that appear to have shattered at some point in their history, creating entirely random and naturally unique looks. You’ll also see stone in a broad assortment of sizes, with streambeds covered by smaller stones that have been ground down to near-perfect, rounded forms.
Become an emulator of nature
It’s not enough simply to be a continuing student of natural streams, waterfalls and ponds. To the very best of your ability, you must also learn how to place stone in a way that makes your ponds look like nature created them. Once you become comfortable using stone in building water gardens, you’ll find that much of your enjoyment of the process comes from emulating nature well.
Work with great stone
You might think you can save a lot of money by collecting stone out of the wilderness and hauling it back home or to the jobsite. Even if you do find a spot where you can gain legal permission to do so, the wear and tear on your vehicle and the amount of time you’ll have to spend collecting enough stone for your water features will likely outweigh any savings you might realize.
Instead, the best approach is simply to buy the material you need from a stone yard. But even there, finding great stone involves doing your homework and becoming something of a detective in identifying local resources and their strengths. (In some cases, you might even end up working directly with a quarry, although they tend to be far off the beaten path.)
It’s also a good idea to work with local resources. Although there’s some appeal to working with stone sources in China or Italy, the downside builds rapidly when the cost of shipping is considered. And if you’re trying for a natural look, there is a distinct advantage to using indigenous stone. It will blend visually with local rock formations and will seem familiar to anyone who sees it.
Different region, different stone
If you’ve studied local watercourses and rock formations, and you apply what you’ve learned only in your local area and customarily choose only local stone, chances are good that you’ve developed routines that will carry you through projects of every scale imaginable.
If your work carries you to different parts of the country (or if you happen to relocate for one reason or another), you’ll immediately discover that different regions offer you different kinds of stone to work with. You need to retool your approach accordingly.
Indeed, each region of the country boasts stone that has its own character and style. Here’s a sampling of some of the stone you can expect to see as you travel around the nation—but be aware that these are broad generalizations. There is a lot of variation in each region.
Northeast: This region boasts more naturally beautiful fieldstone than almost any place else on the planet. As you drive around, you’ll see plenty of examples in the dry-stacked stone walls built many generations ago.
Most stone in this region is well-weathered and is either granite or sandstone. Of course, the best option for the pond builder would be rounded river rock, but that’s becoming increasingly hard to find, because of widespread restrictions on harvesting stone from riverbeds. This doesn’t mean you can’t get any of it; it will just cost more.
As a less-expensive alternative, seek out raw stone varieties that are most like boulders—chunky, irregular and a bit thicker than the thinner, slab-like materials that are so commonly available. And don’t even think about taking a shortcut and collecting stone from any of those dry-stacked walls. These are considered to be historic landmarks in most areas and are protected by law.
South and Southeast: Good stone can be rather hard to come by in many areas of the Deep South, so for most projects you’ll face the added cost of having desirable materials shipped to the jobsite. This is a particular issue in coastal areas, all the way around the Gulf Coast and up the Atlantic seaboard.
As you move inland and approach the Appalachians, however, you’ll find an abundance of beautiful stone of many types, including softer granites, sandstone and some limestone.
Regional moss rock from the mountains of Tennessee and North Carolina is particularly prized for use in waterfalls and in giving ponds an immediate naturalistic quality.
Midwest: Granite boulders predominate in the upper Midwest— Wisconsin and Minnesota and on up into central Canada—while limestone takes center stage in Indiana, Illinois, Iowa and Missouri. In fact, much of the farm belt is loaded with limestone. (For more about limestone, see the sidebar at the end of this article.)
There are pockets in which lots of very nice local stone is readily available, and it’s generally easy to figure things out with visits to local stone yards. That said, this is also a market in which many projects involve bringing in stone from some distance, with fancy moss rock from the Rockies being a popular choice among clients prepared to pay $400 or more per ton.
West and Southwest: Imagine any type of stone and, in general, you’ll be able to find it all over the West. This includes flat or rounded river rocks; weathered, moss-covered granite; various types of volcanic rock; a huge range of sandstones; and lots of limestone. There are so many mountainous areas in the West that are full of beautiful stone and water formations—you never have to look far for inspiration or material.
In fact, visits to good local stone yards can be a bit intimidating; there’s just so much variety in stone types, and the range of available colors is so vast, it’s almost bewildering. Pacific Northwest: This is another region with virtually limitless stone possibilities—and much of it is available at startlingly reasonable prices.
But here it’s often about more than stone: In many projects, you’ll find yourself following nature by inte grating other natural materials into your compositions, including moss, tree branches and stumps.
Among the most common stone types is a uniquely lightweight volcanic rock, which is awesome for building waterfalls—and you can even shape individual stones without much difficulty.
With all of the natural rivers and streams in the region, you might think it would be easy to obtain rounded river rock, but that’s not the case. Environmental restrictions prohibit the disturbance of riverbeds and their surrounding areas, so this type of stone is becoming increasingly difficult to acquire at any price.
As you work with any of these stone types in any of these regions —or even if you never wander beyond a day’s walk from your home base—it’s important to bear in mind that no stone is too common or too boring if you use it well. On the flip side, even the prettiest, most expensive stone can look terrible if you don’t know how stone and water interact in nature.
No matter how you slice it, the fact of the matter is that working with stone is hard work. The more you know, the more observant you are and the more practice you get, the better your results will be.
Limestone: Fact and Fiction Have you ever had anyone tell you that you cannot put limestone in a pond? Although it’s generally true, it is helpful to know that there are exceptions to this rule. Some limestone is very hard and dense, or has been weathered to the point that it is safe to use in a water feature. Moss or lichen growing on limestone (or any stone, for that matter) is a good indication of its possible use in a pond.
With soft or porous limestone, pH and hardness will typically rise because the limestone’s minerals leach into the water. These minerals (basically phosphorous and several other micronutrients) also encourage algae growth. But when the stone has weathered to a point where low-pH-loving plants such as moss can grow, that stone no longer changes pH or hardness.
Obviously, you have to be sure before you introduce limestone into a pond, as pH levels above nine can lead to irritated, stressed fish.
When in doubt, test the stone by pouring on a little vinegar; if it foams and bubbles profusely, you probably don’t want to use it. But if the reaction is only a slight, slow bubbling, then you are dealing with a type of limestone that probably can be used. And don’t be fooled—if there is no bubbling at all, somebody’s trying to sell you something other than limestone!
EDITOR’S NOTE: Ed Beaulieu is vice president of field research at Aquascape Inc.