If we want to consider the ecological function of our yard, a water source is a foundational habitat element. Bird baths and other shallow containers are the most basic ways to support wildlife, but adding a self-sustaining above ground wildlife container pond is an easy way to increase biodiversity by offering food and shelter in addition to water. Container ponds designed for habitat seem to be more popular in the U.K. than the U.S. where water features are usually ornamental and take the form of exotic plants in decorative water gardens, fountains, artificial waterfalls, and koi ponds. This made finding information about my idea to repurpose an unused firepit a bit tricky. I visited a water garden store that was chock-full of things I didn’t need including aeration systems, pumps, filters, fountains, koi fish, lighting, plant fertilizers, and water treatments, but not all that helpful for ideas about creating a container pond focused on supporting wildlife. It reminded me a little bit of when I wanted to make my yard more wildlife friendly using native plants and visited traditional nurseries that were filled with products and plants for ornamental gardens. The folks at the water garden stores didn’t quite understand what I was doing and were a bit too fuzzy for me about some of the plants that they thought might be native.
In the end I used a variety of sources and patched together information about water gardens and container ponds to use what aligned with supporting nature. A wildlife container pond functions much like a rewilded yard that needs little maintenance or human intervention. Hopefully, the following guide will cut through any confusion around the distinction between a decorative water feature and an above ground wildlife habitat container pond. I’m trying to keep the process approachable, adaptable, and economical enough for anyone who wants to support more habitat for wildlife in their yard.
I’m not quite ready or sure about installing an inground pond in my small, urban yard. If you have the space and time, using a large preformed or freeform pond liner or even utility wash tubs or stock tanks is a bit more complicated yet a worthy project to try. If you live where a container might freeze solid in the winter, a bigger inground pond below the frost line (depth the water in the soil freezes in winter) might be your only option.
WHAT A WILDLIFE CONTAINER POND DOES NOT NEED
Koi fish or goldfish are used as ornamental water features and not functionally desirable in a wildlife container pond. They are not native species; cannot survive in smaller containers; need to be fed; reduce biodiversity; are top aquatic pond predators of frogs and other native wildlife; need to be protected from the hungry predators they attract (the opposite of supporting wildlife!); eat native water plants; raise the nutrient level and require aeration; and in Maine even illegal to keep outside.
Since you won't have fish, filters for clean water or pumps to oxygenate and cycle water are unnecessary in a wildlife container pond. If you have mix of native water plants they act as natural water filters and oxygenators.
Crystal clear water is ornamental and not functional. The koi pond aesthetic is so ingrained in our understanding of container ponds that the first question I am invariably asked about mine is how I keep the water clean. If you let nature take its course a wildlife container pond will have water that is transparent enough to see what is in it, but just murky enough to be natural. The water in my pond has been somewhat clear since I added it late last summer. I’ll see what happens in the spring, because my understanding is that algae is more common early in the growing season until water plants outcompete them.
There is no need for chemical treatments. In fact, some of the products to combat algae in container ponds contain herbicides which are categorically considered. pesticides!
Pond dyes are sold to cut down on the photosynthesis of submerged plants or to “enhance” the natural color of the water. There is no need for either in a habitat pond ecosystem.
Fertilizers are not needed any more for aquatic native plants than they are for native plants in a rewilded yard. As the pond settles there will be plenty of nutrients for the plants in it.
WHEN TO MAKE A WILDLIFE CONTAINER POND
An ideal time to make the pond is when the growing season is slow to help plants develop their root system and give wildlife plenty of time to find the pond. When I decided to finally make a pond, it was late summer, so I obviously did not follow this suggestion. I did have one lonely green frog show up, but it was not during the time they reproduce. A friend gave me a handful of pollywogs that appeared in his water garden, but I don’t believe they made it. I’ve since learned this was not a good idea because importing any wildlife to your pond might spread potential diseases or invasive species Hopefully, this spring more frogs will naturally find my pond. I've also put out the welcome mat for dragonflies! It will be interesting to see how the native plants I added so in mid-growing season did over the winter.
WHERE TO PLACE A WILDLIFE CONTAINER POND
For the safety of young neighborhood children, don’t put the wildlife pond in the front yard. If you have very young children, research how to safeguard them if you add a wildlife container pond anywhere in your yard, no matter how small.
For wildlife, particularly in warmer climates like the Southeast, a partially sunny spot with afternoon shade works best. A spot in full sun will not offer a cool respite for wildlife on a hot day, will evaporate quickly, and can also cause an algae bloom which can deprive the pond of oxygen.
Many native plants that thrive in sunny, wet spots will do okay in a partially sunny container garden.
Don’t forget to find a way to place the pond where you can experience the joy of seeing plants and wildlife thrive in the habitat you created. You will also want to take advantage of the mental health benefits of spending time near water, even if it’s just a micro-pond! If the pond must be out of view, consider using a wildlife trail camera. (I won't share just how much time I spend looking outside my back kitchen door where the video below and most of the images of birds and wildlife in and around my pond are taken.)
WHAT TO USE AS A CONTAINER
To create a healthy and functioning container pond, you need a waterproof container at least 18” in diameter and 5”-8” deep. A 35-gallon Behrens round steel utility tub I found at a local hardware store fits perfectly inside our standard firepit kit. If you are not repurposing a firepit like I did, metal stock tanks and utility tubs come in a variety of sizes and shapes.
The path of least resistance is finding a container that can safely hold water, but there are tutorials for adding pond liner or a silicone-based sealant to containers that aren’t watertight.
Half whisky barrels are popular options, but if you one or any container with semi-porous materials you need to line the container with pond liner to prevent whatever was in it from leaching in the water.
NATIVE PLANTS
Native plants are the key to a healthy pond habitat. They take in carbon dioxide and release oxygen, offer cover from predators, resting options and food for pondlife, and contribute to a life supporting aquatic ecosystem. I tried to keep my eye on function when sorting through what plants to add to my pond. I asked native plant friends, a native plant nursery owner, traditional water garden store staff, and of course I scoured online articles sifting through all the advice. I discarded the “thriller, filler, and spiller” philosophy for adding aquatic plants based on looks since the fillers were often invasive plants like water lettuce or hydrilla. I also didn’t follow advice for larger wildlife pond information that doesn’t make sense in a small, simple, above ground container pond.
For the average person, buying native aquatic plants is a whole new game to learn even if you’re familiar with native plants. The aquarium and horticultural trade has had such an impact on aquatic plants that it’s made finding native plants for a habitat focused pond a minefield.
Most aquatic plants sold are non-native in all or part of the country, and some are even invasive (such as common water hyacinth/Eichhornia crassipes, hydrilla/Hydrilla verticillate, dwarf waterclover/Marsilea minuta, and anacharis/Egeria densis).
If you do find aquatic native plants at a water garden store they might not be native in the state they're sold! For example, Elodia (canadensis or nuttallii) is a native not found in Georgia or along the southern part of Gulf Coast states but sold in Georgia as some water garden stores.
If a plant is either not native or a native that won't make it through the winter where you live, it's not the “right plant, right place” for your pond.
Also, it may go without saying, but aquatic plants should never be taken from wild ponds.
Native Pond Plant Categories
In broad terms pond plant categories include marginals, floaters, and submerged plants.
Generally marginal plants grow at the edges of wet areas of terrestrial and aquatic environments. Floaters and submerged plants are aquatic plants that grow in water. This includes semi-aquatic plants that grow in damp soil.
When choosing plants think about adding flowering and even host plants for pollinators. In my pond, a hummingbird found the tiny cardinal flower (Lobelia cardinalis) the minute it flowered and the small pollinators were all over the slip of swamp milkweed (Asclepias incarnata) I added. Add at least one plant with a tall stem such as copper iris (Iris fulva) for emerging larvae of damselflies or dragonflies to crawl up when they’re ready to leave the pond and turn into adults.
Marginal plants
Marginal or emergent plants have their roots, crown and often lower foliage growing underwater. These are not necessarily aquatic plants so it’s easier to find them if you visit your local native plant nursery and bend their ear. Many native plants that grow in damp soil can also grow in shallow (12” or less) water which is about the depth of a 35-gallon container pond. Bog plants are marginal plants barely covered by water and include carnivorous pitcher plants.
The following list of native plants are already happily growing in slightly damp areas of my Atlanta yard and will also grow in the shallow standing water of a wildlife container pond.
Jack in the pulpit (Arisaema triphyllum)
swamp milkweed (Asclepias incarnata)
marsh marigold (Caltha palustris)
native sedges - bristly sedge (Carex comosa), shallow sedge (Carex lurida), and fox sedge (Carex vulpinoidea). Research native sedges that might a fit where you live.
white turtlehead (Chelone glabra)
copper iris (Iris fulva)
cardinal flower (Lobelia cardinalis)
monkey flower – (Mimulus ringens)
obedient plant (Physostegia virginiana)
blue vervain (Verbena hastata)
Some native wetland plants can be a bit harder to find. The following are the more common ones.
spikerush (Eleocharis obtusa)
marsh rattlesnake-master (Eryngium aquaticum)
Scouring or rough horsetail (Equisetum hyemale)
Southern blue flag (Iris virginica shrevei)
Soft rush (Juncus effusus)
pickerelweed (Pontederia cordata)
*Don't listen to anyone who suggests yellow flag iris (Iris pseudocorus) and tells you how "easy" it is. This is a pernicious and invasive species in much of the United States!
Submerged plants
Submerged plants are often called oxygenators for ponds with fish and get nutrients in the water through their leaves and stems, keep the water clean of algae, and offer a habitat for larvae and frogs at all stages of life to hide from predators. Many of the submerged plants sold for aquariums or water gardens are marginal plants that would naturally grow near the edge of water. Native aquatic submerged plants are often difficult to find locally. Some sources suggest that small spaces don’t need submerged plants, so they are not essential. If you add them to a pond, tie the bottom of the plant to a small stone so it will be anchored to the bottom of your pond. A friends gave me slips of hornwort (Ceratophyllum demersum) and lizard’s tail (Saururus cernuus) - two of the easier to find submerged plants.
Floaters
Floating pond plants absorb large amounts of nutrients from the water, offer resting spaces for small pondlife, and shade the water when it’s hot. Finding floater plants can be a challenge because most floaters sold are non-native and, at least in Atlanta, there isn't an aquatic native plant nursery to turn to. Iconic native floaters like American water lilies (Nymphaea odorata) and American Lotus (Nelumbo lutea) are just too large for a small container pond. American water lilies are also considered invasive in some western states. Lemon bacopa (Bacopa caroliniana) or water-hyssop (Bocapa rotundifolia) are floaters that can also be submerged.
I asked around in my own online circles if anyone had a floater to share with me, and a plant friend who works for a water conservation organization came through with American frogbit (Limnobium spongia), a native aquatic plant that can also be confused with invasive water hyacinth (Eichhornia crassipes). Frogbit is an example of how complicated the aquatic plant trade is and the reason to look up the scientific name of any plant you might add to your pond. Both European frogbit (Hydrocharis morsus-ranae) and West Indian spongeplant also called Amazon frogbit (Limnobium laevigatum) are invasive in part of the United States.
Aquatic Soil
After asking the owner of a local naïve plant nursery and friends for suggestions of what medium to plant the marginal plants in, I made an aquatic soil mixture of coir, permatill, sand, and soil conditioner with small pebble on the top to hold the soil a bit. Peat is often suggested in the mix, but I try hard not to use it because it’s not a sustainable option.
Adding Native Plants to the Pond
For a pond in a 35-gallon container five plants are plenty. Add more or less depending on what size container you use. I picked multiple native plants from the lists above and planted them in two 10-gallon nursery containers. I poked a few more holes on the side of the pots and placed them in the container pond on top of flat pavers. The top was flush with the water. Some aquatic plants can be fast growing and vigorous, so my idea is to continue to monitor them this year and edit or remove as needed.
HOW TO BUILD A WILDLIFE CONTAINER POND
When I told my husband I was writing this post, he didn’t quite understand why I was working on it for so long because putting together the pond is straightforward and doesn't take much time to finish once you have all the necessary materials. He didn’t realize all the background work I did to learn as much as possible before making the pond.
Supplies
To get started you need: a container; pea gravel; bricks, stones or small inverted terra cotta pots; large flat stones; short, thick branches; native plants potted up in a pond-friendly medium, water (preferably rainwater)
Building the Pond
Creating wildlife accessibility to counteract the straight sides of above ground containers is essential. Pile bricks, stones, or small inverted terra cotta pots on one side of the container to create underwater ramps or shelves to help frogs and other critters get in and out of the pond, and as steps for adding plants. Add large stones on top of the bricks that won’t have plants on them to create a platform for wildlife on top of the water. Submerge a couple thick branches that also stick out of the water as an escape for wildlife if they fall in, as well as a resting place for wildlife living in and visiting the pond. The branches also add nutrients to the water as they break down.
Line the bottom of the container with pea gravel after adding the ramps. I learned the hard way and did this before adding the ramp element and had to clear space to make the bottom bricks even.
Strategically place smaller pots of native plants on the bricks, stones, or inverted pots so the top of them will be flush with the water when the container is filled. You can also add fewer large pots filled with multiple native plants in each. This is what I did as an experiment to learn more about how plants grow in container ponds.
Once everything is in place, gently fill the pond with water. Water from a rain barrel is ideal for the first time you fill the wildlife container pond. If you don't use rainwater, most guidelines suggest letting the water sit for a day before adding the plants which makes it difficult to position the plants. The main reason for letting the water sit is to allow the chorine to dissipate which is important in a decorative pond with fish or once a pond is established and has frogs in it. I didn’t have rainwater and filled my pond with hose water after adding the plants and they were all fine.
OTHER CONSIDERATIONS
Wildlife Accessibility and Support OUTSIDE the Pond
The pond is the equivalent of an above ground pool, and smaller wildlife may need stacked stones, slate pieces, or a log leaning against the outside the container to get to pond.
The area around the pond is also considered habitat. Add native plants including native grasses and shrubs as cover from predators for wildlife and birds visiting the pond, and for nesting sites. (My winter project is to find someone to remove the landscape fabric that was put down around the firepit when it was built before I knew about the fabric killing the life beneath it. Once this is done I'll replant a native plant pocket prairie on one side and native shrubs on the other side of the pond. I have a variety of plants sitting in pots ready to go!)
Logs or stumps add biodiversity and support the life beneath them and around the pond as they decompose.
If you don’t have large rocks in your yard, decorative stones or pavers give wildlife a place to hide under and sun on.
Fountain or no fountain?
Moving water attracts birds and deters mosquitoes. I added a solar surface fountain to my pond and learned they only work when the sun is directly on them (duh!) after buying two thinking the first one was broken. I removed the fountain because it seemed a bit fussy for attracting wildlife but may revisit the idea this spring. When it warms up I may also just go DIY and follow one of the many clever bird dripper tutorials that show how to use a container above a water element to create a slow drip.
Mosquitoes
The second most asked question about my wildlife habitat pond is what I do about mosquitoes. A rewilded yard is not mosquito-free because as annoying as they are to us, mosquitoes are part of the ecosystem (and there's no escaping mosquitoes in places like Atlanta!) A healthy, functioning wildlife container pond doesn’t contribute to the mosquito population and if mosquitoes lay eggs in the water, predators appear including frogs and dragonfly larvae, bats and birds that feast on mosquitoes. For example, my resident bluebird couple raised three broods in my yard last year. Each bluebird needs 2,000 insects a day to survive – and they love mosquitoes!
Some folks put mosquito dunks or bits in their pond. They contain a Bti larvicide that kills other aquatic insects in addition to mosquito larvae. If we're going for a healthy ecosystem, it makes much more sense to let the natural predators do their thing!
Maintenance
Unlike ornamental water features that require constant maintenance to keep them pristine for people (not wildlife) there needs to be as little disruption or intrusion as possible to the ecosystem of a wildlife container pond. Yet, there are a few small maintenance considerations to keep track of.
Evaporation - Keep the water level topped off when it evaporates, especially in hot weather. I fill a two-gallon container with water and let it sit for a couple days so the chlorine evaporates before gently adding it to the pond, so I don’t disturb the life in the water too much.
Cleaning - Some leaves and plant matter sink to the bottom and contribute to the functioning ecosystem of the pond. Frogs and other aquatic wildlife prefer an underwater maze of natural matter and plants to hunt, hide, feed, and breed in. During peak fall leaf season, I removed an overabundance of large tulip poplar leaves and pinecones from my pond. The goal is not to have a clean and tidy pond, but I didn’t want them to change the PH balance and overwhelm the natural functioning of the pond in any way.
So far, I haven’t had an issue with algae even in the hottest and driest part of summer. If it starts taking over, it will need to be scooped out a bit. I believe fish cause nitrate and phosphate levels to rise, which causes algae. Not having fish should make this less of an issue.
Plant care
Even if a native plant might be more aggressive in a natural setting, it will be easy to keep in check in a wildlife container pond. To ensure plants don’t overtake the pond space, exuberant plants need to be edited out in late fall.
FINAL THOUGHTS
I was compelled to add a wildlife container pond after I watched how essential the smaller water sources around my rewilded yard were to wildlife all year long. If you’re on the fence about adding water to your outdoor space, any worries will be outweighed by the miracle of wildlife finding this habitat element once you offer it. Less than a month after I added my wildlife container pond a green frog appeared, birds started using it for bathing and drinking, and my cute little yard chipmunks and grey squirrels stopped by for their daily hydration. Even now in the middle of winter flocks of robins, red-winged blackbirds, and cedar-waxwings, along with bluebird, goldfinch and song sparrow families routinely visit the pond. Stay tuned for future posts with details about the native plants in and around my little pond and the diversity of life it is supporting.
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