Building a Small Backyard Pond Around Rocks and Under Trees
Building a Garden Pond Is a Fun and Rewarding DIY Project
Our small garden pond is tucked between an outcropping of natural granite boulders and under several large oak trees. While most guides for creating water gardens and backyard ponds recommend building garden ponds on a flat, level area in full sun and away from trees and rocks (and this is very good advice), our yard does not offer such optimal conditions. But this did not stop us from building a successful, unique and beautiful garden pond that is filled with healthy plants and fish, and rewarded us with years of enjoyment.
Left behind from the retreating glacier that covered the Northeast during the last Ice Age, the granite ledge and large rock outcroppings in our backyard provided a dramatic backdrop for building a little garden pond. A gap between two boulders left a natural trough that was perfect for building a little stream to trickle down towards the pond, cascading over the edge of a waterfall and then spilling into a small pond that we dug out between the rocks and contained with a cinder block retaining wall.
Building this small garden pond in an area surrounded by ledge and boulders, under trees and on a slight slope was a challenging project, but it was a lot of fun too.
Preparing the Site
We used a garden hose to layout the perimeter of the pond. When building your garden pond, outline as large an area as possible; though the pond may seem huge initially, most pond owners wish that they had made their pond a little larger and a bit deeper. Our small garden pond is a teardrop shape, approximately 11 feet long and six across at the longest and widest points, and almost three feet deep.
Since we were digging the pond into a slight slope and around huge chucks of immovable granite rock, we marked the highest point that would indicate the surface of the pond, and then used a string with a line level to determine which sections of the pond's edge were below this point. This gave us an idea of the angle of the slope, and the height of retaining wall need to contain the low end of the garden pond.
The low point of our garden pond was nearly 24 inches below the highest point near the water fall. To contain the water on the low end, we built a low retaining wall with full sized and half sized concrete block, and covered the concrete block wall under a berm of dirt. Low block walls can be dry stacked, but use mortar for any block wall more than two courses high.
Digging the hole for our small garden pond was a manual effort, one shovel full of dirt at a time. Though a renting or hiring backhoe would have made the job easier, locating our pond between the large boulders made it difficult to position a backhoe around the rocks to help with the digging. The end result was a lot of shoveling by hand.
We dug down as deep as we could, until we hit a "floor" of ledge rock. We used the dirt removed from the hole to backfill the outside of the retaining wall. Dig your pond down at least 3 feet deep (and deeper, if possible), especially if you live in an area with cold winter seasons. If you plan to keep fish in your pond, the extra depth prevents the pond from freezing solid during the winter. Deeper water also stays cooler during the summer months, and the fish can hide in the depths from predators such as herons and raccoons.
Laying the Pond Liner
Layer the bottom and sides of the hole with thick layers of newspapers and old carpet padding to protect the pond liner from tree roots and sharp rock. Then, stretch out a thick rubber liner along the bottom, ensuring enough of the liner extends over all of the edges around the pond and above the high water mark. The bottom of our garden pond is layered with a thick rubber roofing liner, purchased from a commercial roofing company that we found online, and completely overlaps the retaining wall.
Started at the bottom edge of the cinder block retaining, we added layers of field stone to create a rock wall inside the pond with shelves for plants and crevices for fish to hide. Slowly, we added water to the pond, adjusting and smoothing the pond liner for a custom fit.
The waterfall and stream were lined with more of the rubber liner, cut with a razor knife and fit with sections of rubber liner. We used a specially formulated exterior grade rubber adhesive (often used for rubber roofing) to glue all of the liner seams together, creating a watertight seal. We used the rubber adhesive to glue the rubber liner in place along the rock outcroppings. The rubber adhesive bonds very well with the rough texture of the rock, and has held up well for many years.
We continued adding field stone to cover the liner and to disguise both sides of the retaining wall. The spillway for the waterfall was created by carefully selecting and positioning smaller rocks. Adding smaller rocks and pebbles filled in the gaps between the larger rocks, further disguising the retaining wall. Planting patches of moss softened the hard look of the rock, and the small patches of moss spread quickly.
Filling the pond slowly with water (a garden hose works fine), we paid close attention to the liner. Keeping the liner taunt and pressing the liner down against the bottom and up along the sides of the pond as it slowly begins to fill with water reduces unsightly folds. Tucking the liner under the rocks that form the capstones along the top edges of the pond holds the liner in place and finishes the edges with a natural look.
The water might be mucky when you turn on the pump and filter, but the sediment will settle and the water should clear up after a few days. Wait at least a week before adding any fish, especially if using city water. The waiting period allows chlorine and other additives to evaporate, and for the water temperature to moderate to your local climate.
After many years, this unconventional garden pond is home to a small but healthy population of koi, goldfish, frogs, and insects. The aquatic plants thrive, though the mostly shaded environment limits the blooms of the hardy water lilies which require full sun. Even with these limitations, the pond and stream offer a year-round water source for the local wildlife. So don't let less-than-ideal yard conditions stop you from building a small garden pond. The results are worth the efforts!
Our Small Garden Pond
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Observation Will Help You to Purchase Healthier Fish
Buying Pond Fish for Your Garden Pond
A healthy fish has a better chance of surviving the transition and travel from a breeder through distribution in the pet trade and ultimately to your garden pond. When shopping for pond fish, it is important to buy from a reputable and qualified dealer. The big pet retailers may offer the lowest prices on koi and goldfish, but selections of their stock are usually limited to the more popular species that sell in higher volumes. Aquarist specialty shops, koi breeders and garden centers are more likely to cater to intermediate and advanced hobbyists, and these specialists often carry more unusual and exotic types of koi and goldfish as well as the standard breeds.
Examine the condition of the tanks carefully before making a purchase. The tanks should be clean and well lit. Some retailers use a centralized filtration system, while others use individual filters in each tank. Both have advantages and disadvantages, and either can be effective filtration methods when maintained properly. Look for clear, moving water without accumulations of debris. Cloudy water or dead fish left in the tank are strong indicators of problems and should be avoided.
When selecting a fish to buy, look for active individuals with intact fins and bright coloration. Ripped fins can invite pests and diseases, while dull colors or lethargic movements are indicators of poor health. Even the common Comet goldfish have distinctive coloration, fin structure, and movements which can give an indication if a fish is stressed or unhealthy.
After identifying your fish of choice, always ask the salesperson to scoop out the specific fish you have selected. Even in a crowded tank with active occupants, it is relatively easy for an experienced salesperson to single out and net your selections. If the store is busy, it is often to your advantage to let the salespeople help the other customers first so that they will not be as rushed to catch and bag your fish. Ask the salesperson to use large plastic bags and only place one or two fish per bag. The more air and water in the bag per fish, the longer the fish can stay in the bag and the less the temperature of the water will change during the journey home.
Adding New Fish to Your Garden pond
Give Your New Inhabitants a Good Start in Their New Home
Follow These Simple Steps:
Now that you've purchased new fish, it's time to add them to your pond!
- Place the bagged fish into the pond as soon as possible, and then let them float around in their bag for at least 20 to 30 minutes. This time will allow the temperature of the water inside the bag to equalize with the temperature of the water in the pond.
- If your pond has a shallow shelf, stand or wedge the bags upright and open the top for fresh air water. Adding a little pond water into the bag will help the fish to acclimate further to the pond water.
- After the temperatures equalize, gently tip the bag into the pond and allow the fish to swim out. It is not uncommon for the newly introduced fish to seem disoriented, and swim down towards the deeper and darker sections of the pond. It can take a day or two for the new occupants to adjust to their new surroundings and join the rest of the school.
Visit Another Awesome Koi Pond
Beware of Bullfrogs!
Bullfrogs are Carnivorous!
Bullfrogs were welcome at our pond—until we saw one attack and eat a koi fish! If you keep koi and goldfish in your pond, beware of hungry bullfrogs.
Purchased from a local gardening center, we added several bullfrog tadpoles to our pond over the course of several years. Bullfrog tadpoles are large by frog standards, and each plump tadpole was about 4" long when released into the pond. Unlike many frog and toad species that morph from tadpole to adulthood in a single year, bullfrogs spend the first year of their lives as tadpoles. They happily rooted around along the bottom of the pond and between the rocks, searching for food and picking at the algae.
The tadpoles begin the familiar transformation towards becoming a frog during their second year. First, small rear legs appear just under the tail. Then the front legs emerge and the tail begins to shrink as it is absorbed into the growing body of the bullfrog. Before long, we had several bullfrogs living in our pond, along with the frequent visits from small spotted frogs, wood frogs, and spring peepers.
The bullfrogs grew quickly throughout the summer, and most survived the winter under the frozen surface of the pond. After a couple of years, one frog, in particular, grew into a very large, adult bullfrog. We dubbed him Mega Frog, and he usually sat on top of the lily pads in the middle of the pond.
We have a few small koi in the pond, along with with several Sarassas, Shubunkin and comet goldfish plus a handful of small golden feeder fish. The goldfish breed prolifically, and each spring brings a new swarm of little black fry. Occasionally, a fish goes missing when a raccoon or heron grabs a meal. It's sad, but not alarming as some losses are expected to the local predators.
One evening, Mega Frog was perched on his lily pad when we came down to the pond. We always feed the fish from the same overhanging rock, and the fish congregate around the edge of the rock when we approach, looking for their handout of pellets.
This time, as one of our butterfly koi slowly swam past the lily pads, Mega Frog struck. The water in front of the lily pads exploded in a splash and a fraction of a second later, the bullfrog was sitting on a rock with just the forked tail of the koi hanging from his mouth.
Now, Mega Frog and the other bullfrogs live in a large natural pond on a friend's property.
The local wood frogs and peepers are still welcome visitors to our small garden pond, and they do not seem to bother the fish. Since removing the bullfrogs, we've seen more native peepers and wood frogs in our pond - they must not like bullfrogs either!
Our Small Garden Pond
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
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© 2011 Anthony Altorenna