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Gardening with Water Plants

Gardening with Water Plants

Water plants are not only captivatingly beautiful, but they also have the important function of minimizing the build-up of algae in a pond. Without water plants, the water will quickly turn green and cloudy, making it undesirable to fish and other creatures.

Why Does Algae Form?

• Pond water contains elements such as salts and nitrates which remain because evaporation is 100% pure.

• The gradual build-up of these elements is one of the major causes of algae.

• Water plants will absorb both; you just have to establish the right ratio of plants to the volume of water.


• When filling your pond for the first time, let the water sit for a week. It may turn green but do not empty it.

• After a week it will be safe to start adding water plants!

Water Lilies & Lotus

Water Lilies

Water Lilies come in two forms; hardy and tropical. Hardy plants can be cut back and left in the water garden over the winter. Tropical plants are treated as annuals or lifted and wintered inside.

The major visual difference between the two is that hardy Water Lilies bloom sitting on the surface of the water with the foliage while tropical blossoms rise on long stems well above the leaves. Both are easily grown, requiring a minimum of 6 hours sunlight daily, rich soil, and quiet water. They are placed 45 cm – 60 cm (18″ – 24″) deep with 20 cm – 30 cm (8″ – 12″) of water over the crown of a hardy Water Lily and 15 cm – 20 cm (6″ – 8″) over the crown of a tropical.

Hardy Water Lilies bloom yellow, red, apricot, white, and pink.

Tropicals are white, pink, red, yellow, purple-violet, and blue.



Lotus leaves and flowers stand 45 cm – 125 cm (18″ – 48″) above the water depending on the variety. Exotic fragrant blossoms last 3-4 days allowing the unusual seedpod to develop.

  • Lotus requires many weeks of sunny, warm weather and rich soil to bloom well. Hardy to Zone 5, it sometimes won’t flower the first year.
  • To overwinter, ensure your lotus is at least 3.5 feet deep in your water garden to protect the tuber from freezing.
  • The leaves of all Water Lilies and Lotus are attractive as well as very functional. By covering the surface of your pond with lilies and lotus you will minimize evaporation, reduce light that algae needs to grow, and keep the water from heating up.

Floating Plants

• These water plants are classified as “floating” oxygenators. They liberate oxygen that helps to clear the water and they absorb excess nutrients that cause algae.

• Floaters literally float on the surface with their roots dangling in the water, moving wherever the breeze takes them. They shade the water and provide protection for fish.

• They include Water Lettuce with its soft, velvety, blue-green leaves arranged in the form of a rosette, Water Hyacinth with its shiny, leathery leaves and blue flowers, and Duckweed with its tiny leaves and spreading habit. Duckweed is also food to goldfish! Use one plant per square meter (yard) of water.

Water Hyacinth

Submerged Oxygenating Plants

• These plants also keep water clear and they control algae naturally.

• They provide spawning space for fish and provide shelter for baby fish.

• Oxygenating plants are planted in pots that are placed right at the bottom of the pool.

• There are many submerged oxygenating plants to choose from but there should be a maximum of three plants per square meter (yard).


• Planted in shallow water at the edge of a water garden, marginals soften the edge of your feature and give it a natural appearance.

• Hardy shallow water plants include Arrowhead with its distinctive leaf and spikes of delicate white, three petalled flowers. Pickerel Rush produces tight clusters of blue flowers on tall spikes from midsummer to fall. Variegated Sweet Flag is particularly distinctive with slender green and cream leaf blades.

• There are also tropical marginals some of which can be kept indoors as houseplants. Others should be treated as annuals and replaced each year. Remember, always read plant signs carefully to confirm.

How to Plant

  1. Line your open weave black plastic baskets with burlap or black, porous landscape fabric so soil can’t escape and cloud the water.
  2. Use an aquatic soil for water plants and be sure to cover it with washed gravel, pebbles, or small rocks. The added weight keeps the planter from popping to the surface.
  3. Place each planted basket in the pond at the required growing depth of each type of plant. If you need to raise a container higher, be sure to place the riser(s) on an extra piece of EPDM to protect the EPDM liner or Rock Blanket/Underlayment beneath from tears.
  4. To eliminate the salt in a concrete block, immerse it completely in a bucket of water for 24 hours. It will take several weeks for your water plants to start growing. Your water may turn green during that time. There will come a time when the water suddenly clears and, if it doesn’t, keep adding more plants.
  5. Remember that Trapdoor and Melantho Snails live solely on algae. They’re just as important to your miniature ecosystem as the fish, frogs, and dragonflies.

How to get your Water Garden to Survive Winter