Tub water gardens are becoming the wave of the future, especially if you have limited space. They can be placed at your entryway, along the back fence, or on a sturdy deck or balcony.
Water gardens may appear complicated to those unfamiliar with them. The principles of water gardening are similar to those of gardening in soil, making it accessible even to those with limited experience. Tall bog or marginal plants (marginal plants grow at the shores of the water), such as marsh marigold, canna, sedge, taro, and cat tail, grow with their roots submerged and foliage above the water. Submerged or oxygenating plants, like fan wort, anacharis, parrot’s feather, and eel grass, live underwater and compete with algae for nutrients while supplying oxygen. Floating plants, such as duckweed and water lettuce, provide shade and help suppress algae growth. These aquatic plants are essential to creating a complete and thriving landscape.
When considering ornamental tub water gardens, the enchanting water lily and lotus blooms are often the first things that come to mind. There are many other plants such as sedges, grasses, Japanese iris, and many more, that contribute to the garden’s beauty. Aquatic vegetables are not as well-known although they are essential diets in other cultures. Some examples of aquatic crops for small water gardens include taro, Chinese water chestnut, arrowhead, and cat tail.
Aquatic plants can thrive in pots or baskets designed for water gardening. To prevent soil from escaping, use a clay soil or line the pot with two layers of plastic-free newspaper. The size of the pot depends on the type of water plant. Dwarf water lilies and submerged plants typically require pots that are 6″ inches” diameter x 6″ inches” deep. Bog plants, full-sized lilies, and dwarf lotuses need pots that are 12″ across x 6″ inches” deep. Using deeper pots is optional.
Consider a heavy, humus-rich soil such as fertile garden soil, commercial topsoil, or a water plant mix. A clay-type soil is useful to hold everything together while adding nutrients found in clay. Avoid potting soils that contain peat, wood sticks, perlite, or vermiculite as they tend to float. Once you have potted your plant, cover the soil surface with a layer of rinsed gravel, about 1/2 to 1 inch thick, to prevent fish from disturbing the soil.
There are many possibilities when it comes to choosing a container for your aquatic garden. From a birdbath to a 5-gallon bucket or even an old bathtub, any watertight container can work. Keep in mind that larger volumes of water are easier to maintain and dark-colored containers can get too hot in the sun. To keep the water cool, you can partially bury the containers or shade the water with floating plants such as duckweed or azolla.
Select nontoxic materials like untreated wood, plastic, glazed ceramic, or even terra-cotta. If using a previously used container, line it with PVC sheeting to prevent any harmful residues from entering the water. Liners can also be used to make leaky containers watertight.
Prepare Your Tub
When you start a new tub water garden, the water will become cloudy and green due to algae “weeds”. Algae generally dies off by itself in a week or two.
Choose a sunny spot for your tub garden such as by your front door, on a deck or balcony.
The water should not have chlorine when you add your plants and aquatic animals. Fill If your water is chlorinated, then fill it with tap water and let it sit for a day or two to remove chlorine. You can purchase chlorine remover to expedite the process.
Aquatic animals such as fish, tadpoles or other aquatic animals may need more attention especially if you plan to leave for a week. Ensure to understand their needs if you plan to have aquatic animals.
If you’re passionate about water gardening, consider grouping multiple containers together. Decorative containers can house space-hungry plants such as cat tail, lotus, arrowhead, or water hyacinth, and arrange them in a way that showcases their varying heights and textures. Experiment with stacking containers of mixed plants at different levels and incorporate a circulating pump to create beautiful waterfalls. Bear in mind that water lilies do not do well in flowing water — gentle flowing water is okay, though.
Multiple containers allow for the cultivation of plants with different growth conditions. For instance, water lilies thrive in warm, deep, still water, while watercress prefers cool, shallow, circulating water. You can group these containers in a corner of your deck or make them the focal point of your patio. To enhance the serene atmosphere, consider adding a few potted palms to complete your tranquil retreat.
Some Edible Water Plants
- ‘Fontanesia’ Violet-stemmed taro (Colocasia esculenta ‘Fontanesia’, sometimes sold as Xanthosoma violacea): Harvest the tubers from vigorously grown dormant plants. Cook the starchy tubers by steaming, baking, or frying after removing the fibrous brown skin. Taro has a mild, nutty flavor when cooked.
- Chinese water chestnut (Eleocharis tuberosa): Harvest the corms from dormant plants. Peel off the thick outer cover and slice the crisp, white flesh for use in salads and stir-fries.
- Water spinach (Ipomoea aquatica): Pick young shoots and leaves from this vigorous vine. Use it as a green vegetable in Asian dishes or as a substitute for spinach.
- Common watercress (Nasturtium officinale): Pick bright green leaves and small shoots to add a peppery flavor to salads and sandwiches.
- Yellow pond lily (Nuphar lutea): Dig the roots during the dormant season in fall or early spring. Scrub and add them to soups and stews. Dry the seeds in a warm oven, remove the kernels, and lightly boil them to serve like corn.
- Arrowhead or duck potato (Sagittaria latifolia): Harvest the starchy tubers in fall when the tops die and the plant is dormant. Peel and boil or bake them like potatoes.
- Cattail (Typha latifolia): Collect yellow pollen to use as flour. Gather young shoots and slice them into salads or boil them for 15 minutes. Boil the green flower spikes for 5 minutes and consume. After the plants become dormant, dig the roots and harvest the sprouts for next season’s growth, boiling them for 10 minutes.
The Tub Water Garden
To create a successful tub water garden of the same size, you will need
- 2 bunches of submerged plants
- 1 water lily or floating plants to cover most of the surface
- optional: 1 or 2 bog plants for visual height
- Include 2 trap-door water snails to control algae and
- 2 or 3 fish such as goldfish, or guppies to eat insects including mosquito larvae.
Fill the tub with water and let it sit for a day or two so it equilibrates with the area.
Place the oxygenating plants and water lily at the bottom, and the bog plants slightly above the water level.
Wait 2-3 weeks before adding fish.
Regularly remove dead leaves and debris, and top up water lost to evaporation.
You can add more oxygenating plants to combat algae if needed.
In areas with cold snowy winters, you should bring your animals indoors and put them into an aquarium. Alternatively, you can bring your tub garden into a cool garage with a timed grow light. The plants will go dormant, but still need some light energy. Do not feed the animals or plants during the dormant time or they can get ill.
Then, sit back and enjoy your new water garden of the future!