Aquatic Plants

Garden ponds are all the rage in both home gardens and commercial landscapes. With all of the new materials and innovative construction methods that are currently available, their popularity promises to continue growing.  

To stay on the leading edge, you who design, construct and maintain water features should get acquainted with aquatic plants that will make your waterscaping even more attractive. This won't be difficult if you learn the categories of water plants and the roles they play in the environmen­tal balances of ponds and other water features. Consider the following categories of aquatic plants and the roles that they can play in water gardens:

HARDY WATER LILIES  
Hardy lilies come in a wide array of colors, shapes, and sizes. They are reliably perennial from the north­ern reaches of Zone 3, northern United States to the subtropical areas of Zone 11, extreme southern United States. Refer to the hardiness zone map to find out what zone you live in before purchasing plants. The white, pink, red or yellow flowers, often fragrant, float on the water surface and usually open during the day.

Each floating leaf is cut into two lobes. Lily leaves pro­vide a great deal of shade from the heat of the summer sun making algae control easier, as well as allowing fish to retreat underneath the shelter of their leaves. When cold weather comes, the foliage dies and sinks to the bottom. New leaves arise from the submerged rhizomes in the spring.

TROPICAL WATER LILIES  
Tropical water lilies produce vibrant colorful blooms. The flowers, usually carried above the water surface on strong stems, come in brilliant whites, yellows, pinks, reds and lilacs. Their leaves also come in an abundance of sizes, shapes, and colors. Tropical lilies, only hardy to zones 10 and 11 can be planted in colder zones when the water temperature is consistently above 70 degrees Fahrenheit. Most tropicals are treated as annuals each year in colder climates. However, they can be brought inside during the wintertime, if given proper care. In colder climates, they often are grown as annuals, though. Hardy and tropical water lilies are primarily decorative. They also shade the water, keeping it cooler and making algae control easier.

MARGINAL PLANTS
Marginal plants are typically found along the perimeter of ponds, lakes, wetlands, and streams. These plants are used to soften the boulder edges and help create a smooth transition from the water in the pond to the terrestrial planting area surrounding the pond.

HARDY MARGINAL AQUATIC PLANTS
The hardy marginal aquatic   '~ plants grow in shallow water or in moist soil at the edge of water and are reliably perennial. They are many and varied, though all are native to temperate regions. Some will tolerate a wide variety of water depths while others have more exacting require­ments. Sweet flag (Acorus cala­mus), golden sedge (Carex stricta 'Bowles Golden), Houttuynia cordata plena, cattails (Typha spp. and monkey flowers (Mimulus spp.) are among the many hardy marginals. Marginals such as creeping jenny (Lysimachia nummularia) and water forget-me-not (Myosotis palustris) are low growing trailing plants that are excellent for softening the edges of the stream and pond.

TROPICAL MARGINAL AQUATIC PLANTS
The tropical marginal aquatic plants are those that originally grew in subtropical to tropical regions and therefore are not perennial in cooler climates where frost and freezing are common during winter months. These plants can be treated as annuals or brought indoors during cold periods. Some will survive cold spells if kept below the water's surface. Among the many tropical marginals are parrot's feather (Myriophyllum aquaticum), umbrella grass (Cyperus haspan viviparus), hardy water canna (Thalia dealba­ta) and four-leaf water clover (Marsilia mutica).

HARDY FLOATING AQUATIC PLANTS
The hardy floating aquatic plants are just that-they float on the water surface with their roots hanging down into the water below. Most are tropical, but a few are hardy perennials in climates with hard winter freezes. These plants may be used to shade the water, making summer algae control easier. Ivy leaved duck­weed (Lemna triscula); some bladderworts (Utricularia spp.) and water soldier (Stratiotes abides) are among the recommended species in this group.

TROPICAL FLOATING AQUATIC PLANTS
In more northern climates, the tropical floating aquatic plants should be treated as annual, replanting them each year or taking them into a warmer place for winter. Some of these become rampant in warm cli­mates and so are not allowed in some southern states. Water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes) and water fern (Ceratopteris thalictroides) are in this group.

HARDY OXYGENATING AQUATIC PLANTS
These submerged plants are important allies in creat­ing a well-balanced water feature. Oxygenators help reduce algae by directly competing for the same food source. Think of them as nutrient sponges. Hornwort (Ceratophyllum demersum), Canadian pondweed (Elodea canadensis) and water crowsfoot (Ranunculus spp.) are easy-to-grow, hardy oxygenators.

TROPICAL OXYGENATING AQUATIC PLANTS
Most of the hardy oxygenators will tol­erate warmer water, but some become straggly and frail in hot climates. Among the good trop­ical and subtropical oxygenators are Cabomba caroliniana, water wisteria (Hygrophila difformis) and Sagittaria natans. Aquatic plants will add new dimensions to your water features. If you take the time to learn a little about them and their requirements, you'll find them easy to install and easy to care for. They come in many forms and sizes. They vary widely in their environmental needs. It is highly likely that, for any given situation, you can find several species of aquatic plants to fill the bill.