Gardening with aquatics is similar to other forms of gardening in that you have to be aware of proper soil conditions, kinds of containers, proper planting techniques, fertility needs, and after planting care. What makes water gardening unique is that the plants you grow are growing in a water filled environment. Things like water depth, water temperature and proper plant selection are the keys to success. The waterscape creates a pleasant appearance, but also helps create a balanced ecosystem to keep the pond healthy as well as beautiful.
Pond Position: Most water plants do well in direct sunlight. Consider also the exposure to winter wind and the depth of ice that accumulates over winter. When selecting plants, keep in mind the hardiness zone factor. Ponds have varying water movement, from no moving water to swift moving water. Plants need to be chosen that will thrive in the existing water conditions.
Plant Selection: There are five types of water plants that can be included in a pond to achieve perfect balance: Water lilies and lily-like aquatics, marginal plants, bog or moisture-loving plants, submerged or oxygenating plants and floating plants.
Rooted Floating Plants (Water Lilies and Lily-like Aquatics): These grow on the base of the pond and send up leaves and blooms to the surface. Depending on the variety, they may grow a couple of inches to a few feet below the surface of the water. They provide valuable leaf cover to help shade the water, which reduces algae growth. Fish love to hide under the leaves too. Lilies do not do well with strong water movement or splashing water. Most species need full sun 10 hours a day for best blooms. A pond should have approximately one lily for every 0.5 to one square metre (5-10 square feet) of pond surface. There are many different colors and styles of lilies.
Here is a list of species in each color:
‘Gladstone’ has a white blossom and a slight fragrance. Leaves are green with red-striped stems. Plants spread to cover an area from 1.2-2.4m (4 to 8 feet). This plant is best for large pools and should be grown in water 0.3-0.9m (1 to 3 feet) deep.
‘Charlene Strawn’ has a yellow, star-shaped blossom. It is very fragrant and is easy to propagate. The blossom opens in late morning and closes in mid-afternoon.
‘Fabiola’ has a pink blossom with slight fragrance. It has small green leaves and produces flowers very early and late in the season. It works well in small ponds because of compact size.
‘James Brydon‘ has a rosy red blossom. The leaves are bronze-purple to dark green. It blooms later in the season. It grows well in pools that are shaded.
‘Comanche’ opens as a peachy yellow and matures to a coppery orange. Young leaves are purplish, and mature leaves are green with maroon speckles. It works well in medium-sized to large pools.
Marginal Plants (Emergent Plants): These grow in the shallow margins around the edge of the pond. It is helpful if a shelf is incorporated in the pond design to support them. Marginal plants can be decorative, provide shelter from the wind, and offer a bit of shade. These plants do best in still to slow moving water.
Cattails are traditional aquatic plants. They have long narrow leaves and produce brown catkins. There are different species that grow from 0.9-2.1m (3 to 7 feet) tall. These can also be grown as bog plants.
Arrowhead produces white flowers with arrow-shaped leaves. It grows to about 0.6m (2 feet) tall.
Pickerel Rush produces spikes of purple, bluish or white flowers. It grows best in water 30cm (12 inches) deep and enjoys full sun or partial shade.
Bog Plants (Moisture-loving Plants): These grow in damp soil at the edge of ponds and prefer to have only the tips of their roots submerged. They also do best in still to slow moving water. Start with a mixture of marginal plants and bog plants inhabiting about 1/3 of the circumference of the pond.
Horsetails form upright clumps of green stems. They have no leaves, and the tips of the stems have brown cones.
Iris are available in several different varieties. Iris most suited to a bog or moist environment are Japanese (Iris ensata), Yellow Flag (Iris psuedocaorus), Siberian (Iris siberica), and Wild (Iris versicolor). They have slender upright leaves. The flower comes in a variety of colors (white, purple, red, etc.).
Submerged Plants (Oxygenating Plants): The roots of these plants are anchored in soil, but the leaves stay underwater. Their foliage is usually fern-like, lacy, or hairy. They play a vital role in maintaining the pond’s natural balance. These plants use waste nutrients and help purify the water. This, in turn, creates an environment that is unsuitable for algal growth. They also provide cover for microscopic forms of life. It is best to include one bunch (these plants are sold by the ‘bunch’ or handful) for every 0.2 square metres (two square feet) of pond surface. Fewer bunches may be adequate once the natural balance is obtained. Grow a variety of species since each species grows at a different time of year and has different water depth requirements.
Anacharis is a deep green plant with many delicate leaves. It will grow in water 15cm to 1.5m (6 inches to 5 feet) deep.
Vallisneria has ribbon-like, pale green leaves. It grows in water 15-60cm (6 to 24 inches) deep.
Floating Plants (Free-floating Plants): These plants do not need soil or a base of any kind. As the name implies, they are simply suspended in the water. They provide decoration and shade and help reduce algal growth. One bunch is sufficient for every 0.9-1.4 square metres (10-15 square feet). These plants are vigorous growers and will need to be thinned periodically.
Water poppy is an example of a floating plant, but grows in zones 8 to 10. It can grow in zone 3 and 4 if you replace it each spring. It has yellow, 3-petalled flowers that rise above the floating foliage.
In addition to the plants listed above, there are many more suitable plants available for artificial ponds. Choose plants that are right for your situation. Use a mixture of plants that combine texture, fragrance and color. Maintain a balance between submerged and surface plants. No more than 70% of the surface should be covered. An example of a proper mix in an average sized pond 1.8m x 2.4 m and 0.6m deep (6 feet x 8 feet and 2 feet deep) would be: 3 water lilies, 3 surface plants of medium texture, 3 surface plants of fine texture, 16 marginal plants and 36 bunches of submerged plants.
Site Preparation: Place a small amount of water in the pond so the plants do not dry out. Have plants, containers, soil, sand and pea gravel ready.
Containers: plastic container with no holes is recommended 38-50cm in diameter and 25cm deep (15-20 inches in diameter and 10 inches deep) for lilies; 15-50cm (6-20 inch) are suitable for marginal plants; 15cm (6 inch) for submerged plants. The choice will be made based on the plant and the fact that larger containers produce larger plants and smaller containers tend to keep plants smaller in size.
Containers should be wider than deep because water plants have a shallow root system; it also keeps the container from tipping over. Plastic is the best material to use because it is lightweight. The containers should be dark colored because they are not as visible through the water. Handles are a convenient way to move the containers, though they are not necessary. It is best if the containers do not have holes in them (holes allow loose soil to disperse and will cloud the water). Many types of containers can be used: dish pans, buckets, clay pots or special containers from garden shops.
Soil: Heavy clay loam. Heavy clay garden soil is best for most water plants.
Water lilies, lotus, and other aquatic plants do best when they are planted in heavy clay loam soils similar to what you would have in a garden setting. These types of soils are generally well-balanced nutritionally and will support good growth. Do not use an amended soil mix for potting aquatic plants.
Fertiliser: You will need well balanced garden fertilizer: 12-12-12, 5-3-1, 7-12-5 and fertilizer tablets.
Do not use manure or over fertilize, which may lead to water eutrophication (excessive nutrients and decreased amounts of oxygen).
Also you will use sand and pea gravel in planting your water plants.
In order to conveniently adjust the water depth over the pots, bricks blocks or inverted pots can be used as props under the plants to position them.
Planting Different Types of Water Plants: The best time to move most water plants is during their growing season, from late spring until the end of summer. Containerized plants can be moved while dormant and placed in the pond. The best time to move submerged plants is spring or fall. Do not purchase the plants until you are ready to plant because you do not want them to dry out.
Water Lilies: Water Lilies-like plants are extremely dramatic and add fragrance when in flower.
The hardy lilies grow from rhizomes. They are best grown in soil-filled containers set in the pond. Lilies can be introduced to the pond from spring to early fall.
Mix a well-balanced garden fertilizer into the soil at the bottom of the container so it does not leach into the water, yet feeds the lily roots (about 1/2 cup of fertilizer for eight quarts of soil). Bury fertilizer tablets towards the bottom of the container. Fill the container half full of soil. Position the lily and gently add soil around the roots. For hardy water lilies, the rhizome should be placed so that the growing point is directed toward the center and at a slight angle. Be sure to leave the crown uncovered. Spread 1/4 – 1/2 inch layer of pea gravel over the top to hold soil in place (again, be sure the crown is just above soil and gravel line). Position the lily container on cinder blocks in the bottom of the pool. In most cases the crown should be 15-45cm (6-18 inches) below the water line. Check the needs of your particular lily to be sure.
Tropical water lilies are planted much like hardy water lilies with one exception; they are planted in the center of the pot. Lotus is also planted in the center of the pot. Lotus rhizomes should be handled very carefully though, as they are very brittle and subject to damage. Lotus rhizomes are best planted in large containers and should be covered with about 5-10cm (2-4 inch) of soil, keeping the growing tips above soil level.
Bog and Marginal Plants: Bog and marginal plants are suitable for those not able to locate their water garden in sufficient sunlight to support good plant growth. Some bog plants can tolerate as little as three hours of sun and still provide interest to the water garden.
Similar planting techniques and care are given to Bog plants and Marginal plants.
Fill the container about half full of soil. Place the roots of the plant in the soil and continue to fill. Be sure not to plant it too deep. You may want to place 3 plants in one container for a more full look. Keep different species in separate containers, because one species may overwhelm another species. Add one fertilizer tablet. Place the container at the edge of pond or on bricks in the pond. The container rims should be 5-10cm (2-4 inches) below the water line.
Submerged or Oxygenating Plants: These plants help combat algae by consuming excess nutrients while at the same time providing cover for fish and producing oxygen during daylight hours. Roots of these plants are not used for nutrient or water uptake, but only for anchorage.
These plants require a lot less soil than the bog plants and lilies. The soil will have a high proportion of sand and gravel. These plants do not require fertilization because they get their nutrients from the dissolved minerals in the pond water. It is good to plant these in containers because they may grow rapidly and become invasive if planted on the pond bottom.
Plant about five or six bunches (with 6 stems/bunch) in a five-quart pail. Place containers in the pool so leaves are submerged to a depth of 15-40cm (6 to 16 inches).
Floating Plants: Floaters enhance the display of water lilies and lotus as well as adding a finishing touch to the water garden. They are the “ground covers” of the pond world. They may be restricted by a framework to prevent them from moving around or allowed to float freely with the breeze. This produces an ever-changing look to the water surface.
No soil or containers are needed for these plants. The roots hang in the water while the leaves stay above the water.
Throw a bunch on the water surface and they care for themselves.
Care After Planting: Your pond may look bare at first, but after a couple of months the plants will mature and flourish. If your pond water becomes murky and fills with algae, do not change the water. Give the pond time to reach its balance. You may need to add more submerged plants at this time.
Water Lilies: They should be fertilized regularly with one slow release tablet per eight quarts of soil every month during the growing season. Just press a tablet into the soil near the roots. Also remove any yellow or brown leaves, and old blossoms. This helps promote new growth and keeps the pond clean. Remove all the dead vegetation in the fall so the lily can start new in the spring. The hardy varieties thrive in cold areas and need not be removed from ponds as long as the water does not freeze down to the rootstock. It may be necessary to move the container to the bottom of the pool to be sure the lily roots are below the ice freezing level. Be sure to remove the lilies if the pond freezes solid.
For plants that need to be removed: Allow water to drain from soil then trim away foliage. Wrap container in moist burlap or peat moss. Store plant in a cool corner of a basement or garage with 4-12oC (40-55oF), not more, to keep the plants dormant. Cover with plastic garbage bag to keep in moisture. Check regularly and water periodically to keep moist.
Tropical water lilies are handled differently because of their tropical nature. Prior to the first frost, remove these plants from their pots and trim off most of the leaves and roots. Re-pot them into smaller containers and store them in an aquarium tank or other container where they get plenty of light and where the temperature can be maintained at about 20oC (68oF). Some tropical water lilies produce walnut-sized tubers. These can be removed and stored in water at 12-16oC (55-60oF) for the winter. When placed in warm water 21-24oC (70-75oF), they will sprout. They can then be potted in small pots and move to the pond at the appropriate time.
Bog and Marginal Plants: Additional fertilizer tablets should be added when the plants are blooming. You may need to divide and thin the population in one container every one to 3 years.
Submerged: Thin if necessary.
Floating: If they reproduce too quickly, pull them out by hand or with a net. Depending on the species you choose and the type of winter you get, you may need to treat these as annuals and replace each spring. Floaters may be overwintered indoors in aquariums where there is high light.
Remember that overfertilization the pond can lead to algae problems.
Water gardens can include fountains, waterfalls, ponds and elaborate combinations of rockwork and lighting.
Fish and Snails for Water Gardens
Pond creatures can be added to your water container for added interest and to help in maintaining the ecosystem balance. Several small snails are very helpful as they eat algae, fish waste, and decaying organic matter. Fish can be a beneficial addition, because they are good scavangers, cleaning up debris. They also can help control mosquito larva, and other insects. Fish such as goldfish and koi fish are good choices. They do well in the variable water temperatures of a small patio pond plus they eat mosquitoes. Larger containers of 75L (20 gallons) or more can handle one to two goldfish.
Aside from goldfish and koi fish (considered cold water fish) any other exotic fishes will have to be brought inside for the winter.