Building a Pond Garden

By: Jane Zoutman, Master Gardener

Ponds are work to build, need to be maintained and cost money, so why would you want to build one?

A pond attracts wildlife. Depending upon where you live this can be insects like bees and dragonflies, frogs, birds, turtles, garter snakes, ducks, geese, and more. The sound of a waterfall is soothing and helps neutralize the sound of traffic. A pond really only needs cleaning annually at most plus cleaning up the pump once or twice a summer. Costs for starting a pond include the liner, the pond pump, hoses, hired help (if needed) and landscaping. My liner and pump are over 20 years old and still working fine. There are some minor costs annually and I do replace the pump hoses every three or four years.

The first step in building a garden pond is to decide where it should be. The ideal spot is mostly sunny, not under trees and very near your deck or patio so you can enjoy the pond when sitting outside. You will need easy access to a GFI (ground fault circuit interrupter, also called GFCI) electrical outlet and water.

The next step is to decide how big and what shape your pond should be. I recommend the use of a rubber liner, not a plastic form, so your pond can be any shape or size. The largest pond I have built and still maintain is about 12 feet by 6 feet (Figure 1). The smallest pond is about 3 feet by 4 feet (Figure 2). Both are no more than 2 feet deep as that is the maximum depth most municipalities allow. When planning your pond consider how you are going to get into it to do the annual cleaning and how you will create some shallow areas for birds to bathe in. You might want a waterfall or a stream (Figure 6). You can include shelves along the sides: larger shelves about 8 inches below water level to hold plants in pots and a smaller shelf around the entire pond at water level to hold 4 to 6 inch rocks or logs which can hide the rubber liner.

Figure l. North Pond, Fort Whyte Alive (FWA) Summer 2022.
Figure 2.  Frog pond, Victoria Beach.

What you will need and approximate current costs:
1. A submersible pond pump – the size and cost will depend on the size of the pond and height of your waterfall or stream. The pond in Figure 3 is about 1000 gallons plus a waterfall. It requires, at most, a 1500 GPH (gallons per hour) pump. There are calculators and formulas that can be found on-line. The pump should be able to move at least half of the water in the pond through the pump in an hour plus requires extra power to send water to the waterfall. Cost will be about $300 to $400. A smaller pond, 5 ft. X 4 ft., with a waterfall would require a 500 to 700 GPH pump at about $250. Splitters and valves can be used to control water flow. You will also need a hose to reach from the pump to the top of the waterfall or stream. The diameter of a kink-less hose will depend on the size of the outlet on your pump and can be purchased by the foot.

2. Pond Liner – EPDM rubber of 45 mil thickness is the best pond liner. It can last more than 20 years; will not harm fish or wildlife; pieces can be adhered to each other (I never had much luck with that); and it will not get brittle in our climate. For the 12 by 6 ft. pond in Figure 3 you would need:
– Length: 2 ft. +2 ft. for both sides +12 ft. for length +4 ft. extra for ground level and irregular shapes = 20 ft. total.
– Width: 2 ft. + 2 ft. for sides + 6 ft. for width +4 ft. extra for ground level + 1 or 2 more ft. for waterfall = 15 ft total.
– The result is a piece of rubber that is 20 ft X 15 ft. or about 4.5 m X 6 m. The current cost on Amazon.ca is $700. A smaller pond, 5 ft X 4 ft, would require a 13 ft X 12 ft. liner at about $450.

If this is confusing Figure 3 might help.

Figure 3. North Pond under construction, Fort Whyte Alive.

The liner will be heavy but will mould itself to the shape of your pond. It will need protection from punctures with heavy landscape fabric between the liner and the soil or a bunch of old mats works well too. A layer of stones (landscape pebbles about $100) for the bottom of the pond, on top of the rubber liner, will also help protect it. Avoid anything sharp or pointy in or around the pond.

Now dig your pond. Our Manitoba gumbo is heavy digging but is very good for a sturdy pond. Slope the sides inward to increase the stability of the sides. See Figures 4 and 5. Don’t forget to make a mound and maybe large shelf for a waterfall. See Figures 6, 7 and 8 for ideas. Once dug lay down a layer of landscape fabric or old mats to protect the rubber. The rubber is heavy so opening it up and leaving it in the warm sun for a few hours makes it more manageable. You will need help to spread the rubber over the pond. Push it into the bottom and the nooks and crannies as best you can. Put a one or two inch layer of smooth stones in the bottom on top of the liner. Make sure the liner covers the waterfall area. Before adding water you might want to build your waterfall, set up your pump and anything else that will sit on the bottom of your pond. The water will push the rubber down so you should use rocks to hold the liner sides in place (Figure 3).

Figure 4.  South pond under construction.
Figure 5.  South pond adding rubber and stones. I needed help for this.
Figure 6.  North Pond Waterfall, Fort Whyte Alive.
Figure 7. South pond waterfall under construction.
Figure 8.  South Pond Waterfall, construction and planting completed. The branch to the left covers the hose and the cord from the pump

You can now use landscaping, pond plants, logs, rocks or whatever to finish the pond (Figures 9 and 10).

Figure 9. South pond filled and now in need of planting.
Figure 10.  South pond later that same summer.

Once your pond is built or every spring after you clean it you will need to do the following:
1. Fill up the pond with water and add some water conditioner if you plan to keep fish in the pond.
2. Set up the pump. Attach one end of the hose to the pump and run the other to the waterfall. You might want to put the pump in a container to screen out the dirt. This can be purchased or home made using a plastic container and with a piece of screening attached with a bungee cord. Run the pump’s cord to the electrical outlet. I usually disguise where the cord and hose are by pushing them under the edge of rocks or using an interest branch to cover.
3. Let the water run for a few days. The water will become clear. I keep the pump running until Thanksgiving or later, except to clean it.
4. Add your floating and sinking plants to the pond.
5. Add your barley straw bale or barley extract to the pond to minimize algae when the water warms up. I put a bungee cord with a weight, usually a flat rock, around the little barley straw bale or the barley pellet bag so it will sink or I jam it under a rock.

I avoid the use of chemicals. Some good oxygenator plants and a barley straw-bale, pellets or extract will minimize algae and keep the water clear. Fish help by controlling mosquito larva and eating the algae.

In the fall pull out the pump, clean and bring it inside. A pump cannot be left outside to freeze over the winter. Put any fish in an aquarium. Leave the water in the pond to freeze. In spring the pump can be used to drain the water so you can clean the pond. Once drained, as best you can, use a pail, to scoop out old leaves and the sludge that can accumulate on the bottom (a great but smelly fertilizer for your garden). Maybe rinse and do again. You may only have to do this every two or three years.

Pond water will get too warm and grow algae useless the water is at least half shaded. You need pond plants. Pond plants can be purchased at the larger garden centres usually at the beginning of June. Pond plants are sinkers (submergent aquatic plants), floaters (free-floating aquatic and floating-leaved aquatic plants) and ones that like to have only their roots wet (emergent aquatic plants). The only sinker I strongly recommend is hornwort (Ceratophyllum demersum) (Figure 11). It is native to our marshes. It will also survive the winter so if you are careful when cleaning the pond it will be back. I make a small bundle of it and tie it together with a weight of some sort (a large metal washer) and let it sink to the bottom of the pond. It grows like crazy so you don’t need much. Water lilies are can also be planted in the pond. They rarely survive the winter and are expensive. Duckweed (Lemna) is also an interesting floater and free but is will cover the entire pond unless you have fish to eat it. All sorts of interesting plants are happy to stand in a pot in shallow water: banana plants (Musa), taro (Colocasia), blue flag irises (Iris versicolor), papyrus (Cyperus papyrus), canna lily (Canna) and calla lily (Zantedeschia aethiopica), pickerel weed (Pontederia cordata) and there are many more. Great care should be taken not to plant any invasive species. Find aquatic invasive plants listed in the document ‘What not to plant in Manitoba’.

Hornwort in a bundle. Enough for 1 pond.  The plant will oxygenate and help keep the water clear.

If you don’t have the time, energy or money to dig a pond one of my most successful water features is a half barrel partly filled with sand and then lined with a leftover piece of rubber. I stacked some rocks in the barrel for the birds to sit on while bathing. See Figure 12.

Birds love this barrel. I see all sort of birds bathing in it including hawks, hummingbirds, and chickadees. No pump, just a small hose dripping water.

Photos by: Jane Zoutman
Published: May 2023