Preparing Your Pond for Fall and Winter 

If you have a backyard pond or a garden fountain full of plants and fish, you'll need to make plans to prepare them for the colder months that are coming soon.

For example, fertilizing should stop about six weeks before first frost.

"Hardy" plants should generally be allowed to go dormant for the winter. Wait until cold weather starts turning the plant's leaves from green to yellow or brown, then trim off all the foliage, and follow one of the methods described below.

"Tropical" plants, on the other hand, should not be exposed to night temperatures lower than 40 degrees Fahrenheit, and should be moved indoors before their leaves start to change, and kept growing throughout the winter via the Bright Light method.

The Deep Pond method for hardy lilies and marginals: Wait until cold weather starts turning the plant's leaves from green to yellow or brown, then trim off all the foliage, and simply lower the pot into an area of the pond where the water is at least 36" deep.

For best results, keep a small area of the pond free of ice by using a pump, air pump or heater. Move plants back up to their original shallower locations promptly in the Spring. Types reporting the greatest successes include Arrowhead, most Rush, Plantain, Hardy Lily, Iris, Sweetflag, Spider Lily, Glyceria, Sago Pond Plant, Vallisneria americum, Creeping Primrose, Wild Reed, Parrot's Feather and Acorus.

The Flower Bed method for hardy marginals: Bury the plant, pot and all, in a flower bed, and cover with mulch. Return plants to pond promptly in Spring. Types reporting the greatest successes: Arrowhead, Pickerel Rush, Plantain, Sweetflag, Acorus, and Iris. The Dark Indoor method for hardy and semi-hardy marginals: Place pot in a cool dark place, for example a root cellar, attached garage or cool basement.

The idea is to keep the plant cool and dark enough to remain dormant. Plant should be watered regularly, or more simply immersed in a bucket of water. The plant still needs to "breathe", so it should not be sealed off from air. Types reporting the greatest successes: Hardy Lily, Iris, most Rush, Plantain, Sweetflag, Canna and Longwood Canna, Cattail, and Wild Reed.

The Dry Root method for hardy or semi-hardy marginals: Unpot plant, then trim roots from tuber and rinse clean. Store tuber in cool dry place. Alternately, remove foliage only, then leave in dry, dark, cool place.

Types reporting the greatest successes: Canna and Longwood Canna. The Bright Light method for tropical marginals: Move plant indoors before leaves start to lose color. Keep in sunny window or under very strong fluorescent or metal halide lighting. Water thoroughly throughout the winter, or keep in kiddy pool or other indoor "pond". Reported successes: Taro, Tropical Lily, Parrot's Feather, Umbrella Palm, Papyrus and Water Poppy.