I just started my pond last year about this time. I threw in about 6
small bundles of anacharis to act a oxygenators. Some developed into
real underwater bushes which overwintered just fine in the pond. Now
they are blooming. They produce small white flowers that look like the
are just blooming out of the water. Quite nice.

Even some parrots feather survived the winter.
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Pardon my spam deterrent; send email to
18,000 gallon (17'x 47'x 2-4') lily pond garden in Zone 6
Cheers, Steve Henning in Reading, PA USA