Cannas are native to moist areas and many do quite well if grown in water, as long as they are not submerged too deeply. The cannas in the pool at the U.S. National Arboretum are varieties of Canna glauca or hybrids between Canna glauca and other canna species. They may also be grown in bog plantings where the soil is constantly saturated. Garden cannas are surprisingly adaptable to wet conditions and some may be grown in water if temperatures are warm. The rhizomes of all cannas rot in cold, saturated soil, so they cannot live over the winter in the aquatic garden.
Make sure that you have not overstocked your pond with fish. Also make sure that you are not overfeeding your fish. Uneaten food is source of nutrients that translates into algal growth, and a large population of fish produces a large amount of nutrients when they excrete waste products. A pond biofilter can help remove excess nutrients and keep the water clear. You can also add water to the pond periodically to dilute nutrients if you have an overflow system that can drain excess water out of the pond. Barley straw discourages the growth of certain types of algae. Pond supply firms sell barley straw products that can be submerged in your pond. Dyes are available that can be added to the water. The black material absorbs the sun's light energy and deprives the algae of the light it needs to carry out photosynthesis and survive. Dye products have the added advantages of protecting your fish from predators and concealing plumbing and pots in your pond.
Many aquatic plant gardeners are tempted to drain the pond, clean it,
and start over with fresh water when confronted with algae. This
is usually counterproductive since the excess nutrients that cause algae
to grow build rapidly in the fresh water. Frequent water changes
and cleaning can make for drastic changes in pond pH and are stressful
for fish and other aquatic life. Only drain and clean your pond when
a substantial layer of decaying organic matter has accumulated at the bottom.
If you choose to keep fish in your pond, make sure they don't have the
opportunity to escape to natural waterways in your neighborhood where they
can compete with and displace native fish species.
For more information on koi, visit the Associated Koi Clubs of America web site at www.akca.org or the Zen Nippon Airinkai at www.anabuki.co.jp/zna/english.
If you're interested in Victoria water lilies, you can find more information at www.mobot.org/MOBOT/hort/lily.
If you want some tips on finding sources for water lilies and other plants for the aquatic garden, check the Plant Sources Page
Last Updated May 13, 2002
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