Aquatics Unlimited: Articles: Pond Plants
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Pond Plants

What do the terms "hardy" and "tropical" mean when referring to lilies or other water plants? "Hardy" essentially means the same as "perennial" - in other words, they should survive the winters outdoors. Check the plant poster for plants that are hardy in our area. The opposite of "hardy" is "tropical", meaning they will not usually survive our winters. "Hardy" has nothing to do with how sturdy or adaptable a plant is; there are sturdy, easy to grow, plants in both the "hardy" and "tropical" groups.

What does the term "marginal" mean? Plants that grow on the edge, or margin, of a pond, usually requiring 0-6 inches of water above their crown.

List benefits of having plants in a pond. They filter out nutrients that otherwise feed algae; they provide hiding places for fish; they greatly enhance the beauty of the pond; they provide shade which cools the pond and further reduces algae growth.

Give examples of hardy marginals, and examples of tropical marginals? "Hardy"s would include Acoris, Aquatic Mint, Arum, Arrowhead, Bog Bean, Cattails, Clover, Golden Club, Houttonia, Iris, Lizard's Tail, Plantain, and most Rush. Tropicals would include Blue Bells, Bog Lily, Cannas, Papyrus Sagittaria, Spider Lily, Taros, Thalia, Umbrella Palm, Water Hibiscus, and Zephyr Lily.

How much of the pond surface should be covered with plants? Ideally, two-thirds to three-quarters should be covered at the season's peak, but half is a pretty good start.

How far under the water should marginals be placed? The top of the pot should be between 1 and 6 inches under water. Some very tall varieties, such as Papyrus and Cattails, might be placed as deep as 12" after they are well grown.

How far under the water should a potted water lily be placed? Most lilies should be kept in between 18 and 30 inches of water, although they should be started much shallower (6"-12") in the spring to be exposed to more sunlight.

How often and how much should water plants be fertilized? That depends on the exact type of fertilizer used, the growth and flowering habits of the individual plants and the season. Rapidly growing plants in a warm summer month use much more fertilizer than slower growing plants in cooler weather. Follow directions on package for dosage.

How do you winter a hardy and a tropical plant? "Hardy"s should have all the foliage removed, then kept wet in a cool, dark place. The bottom of a deep pond (36" or more) is a good place to winter them, as is a cool basement. Some people bury them, pot and all, in a planting bed, and cover them with mulch. If kept indoors, they should remain wet and open to the air. "Tropicals" generally need to be kept growing all winter; some (example: Taro) can be kept in a bright window or under very bright plant light bulbs. Some probably would require a greenhouse to survive (example: Hyacinths), and are probably best treated as annuals. See our Wintering Guide for more details.

When planting pond plants, what would be the advantage of using the pots with all the little holes in them? They allow roots to spread, and allow plants to develop specialized fine feeder roots that grow through the holes and extract nutrients from the pond. They also allow numerous pots to root together, forming a large mass that is harder for wind or animals to knock over.

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