Waterplants
WATER GARDENS AND PLANTS A FEW WORDS BEFORE STARTING A POND – Water gardening is one of the fastest growing areas in gardening today. Whether you want to have a modest container on the deck or a 4 acre pond in the back yard you must be willing to "dig in" with both feet and do the necessary research before even one finger gets wet. The number of water lilies that you have blooming in July and the speed with which your parrot feather takes over in August is directly related to how well prepared you are from the start. Read water garden books when there is still 2 feet of snow on the ground, ask questions of local pond owners and knowledgeable garden center staff, visit existing ponds and take notes. Know what’s involved before you take home 6 marginal water plants, one water lily, a bag full of goldfish and a bucket. Set yourself up for success early. The results will be worthy of your effort. TROPICAL vs. HARDY – Water plants are divided into two major groups: tropical and hardy. Tropical water plants are those which are native to tropical climate zones and will not over-winter outside in our climate. They generally do not need a period of dormancy. Hardy water plants are tolerant of our climate zone. Depending on the type of water garden, ( pond liner, container, natural bottom ) and site specific conditions, ( water depth, freezing, exposure) these plants can be overwintered outside in Wisconsin. Hardy water plants need to go through a period of dormancy. MARGINAL WATER PLANTS and WATER DEPTH – Marginal water plants are those that can tolerate water over their crown on a consistent basis. This measurement is noted on the list as water depth.. They are usually placed or planted on a shallow ledge, although some plants can take up to 12" and may be elevated by a brick base in deeper water. At the very least most of these plants need a minimum of water-saturated soil to survive. Marginals are classified as either tropical or hardy. FLOATERS and OXYGENATORS – Floaters and oxygenators are two more types of water plants. Floaters are plants which float on the surface of the water. Their roots do not grow in soil, rather they dangle beneath the floating foliage above. Floaters are important to a well-balanced pond in that they provide valuable gas exchange and physical cover for fish. They also block out some sun which can otherwise encourage rampant algae growth and raise water temperature. Oxygenators are plants which grow completely submerged in water. Their roots are normally anchored on the bottom of a pond or in a deep container. They produce oxygen through photosynthesis and can fight algae growth when you have large numbers of them. Both floaters and oxygenators are critical if you plan to incorporate fish into your pond. BOG and MOISTURE LOVING PLANTS – Bog and moisture loving plants provide the ideal transition between pond and garden. This group of plants thrives in wet areas where the soil is saturated and poorly drained. In a natural setting this occurs at the edges of some ponds. To create this in a manmade situation, extend the liner of your pond and cover it with the appropriate amount and type of soil. You can create the appearance of a boggy edge and greatly enhanced the variety of plants available to you. WATER LILIES and LOTUS – Water lilies and lotus provide some of the most stunning blooms in the water garden. They usually are set in a deeper part of the pond, requiring at least 12" over their crown. Both provide valuable surface coverage to reduce algae and lower water temperatures. Water lilies multiply rapidly through their spreading tubers and it will be necessary to repot them after just a few seasons. Although there are both tropical and hardy varieties, our garden center carries only hardy types of water lilies and lotus. This is due to the high cost of most tropical varieties and the difficult nature of overwintering these types. SUN, SHADE and TEMPERATURE - Most water plants thrive in full-sun locations. At least 6-8 hours of direct sun are required for most of these plants to bloom. However do not overlook the many plants that tolerate half-shade and full-shade conditions because they provide interesting foliage accents as well as the occasional showy bloom. Don’t rush the season by installing water plants too early. Some tropical plants need water temperatures of 65-75F. Hardy marginal plants may only need water temperatures of 45-50F, but keep in mind that air temperature and water temperature are different. It takes prolonged, steady, warm weather to sufficently increase water temperature. WINTER CARE OF PLANTS – You will need to overwinter your plants inside if any of the following conditions exist: your plants are in containers, your pond is not deep enough to overwinter plants outside, or your pond will freeze solid. Hardy marginal plants and hardy water lilies should be removed from the water and old foliage trimmed back to about 3" above the crown. Place them in a loose plastic bag or styrofoam cooler in a cool ( 40F is best ) and dark place. Keep them damp, but not standing in water. Check soil moisture once a month. Most tropical marginal plants do not like to go dormant so they need special care. Bring them in before the first frost, clean off dead foliage and leggy growth. Place the pot in a dish of water and keep in a warm, sunny spot. The plant will not put on growth, you are just maintaining it through the winter. Some tropical plants that can be induced into dormancy with little ill effect. Water Cannas can be held in a dormant state by letting them dry down and storing them in damp peat moss. It is not a reduced temperature that induces this dormancy but a reduction of moisture. All floating plants are tropical and to successfully overwinter them you will need to grow them in an aquarium with strong sunlight and warm temperatures. Even in the most perfect setting they do not always make it. FERTILIZING and REPOTTING – Repotting and dividing should always occur in spring as you are getting ready to put the plants back into the water. Use the appropriate soil and container suitable to the plant. Remember to put a 1-2" layer of sand or gravel on top of the soil so that it does not cloud the water as you place the plants back into the pond. It is a good idea to fertilize with pond tabs which are placed into the soil in spring.
Drawing from The Stream Garden. Archie Skinner and David Arscott. London: Ward Lock. 1996. Pg. 80.
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Full Sun 
Part - Sun / Part - Shade
Shade
PONDS and CONTAINERS – Water gardening can take place in an unlimited number
of containers, natural bottom ponds, pvc-lined ponds, old bathtubs, lined whiskey barrels
or just a small watertight pot. Your imagination is your only limitation. The size of your
water garden usually determines the number and types of products you will need to keep it
clean and healthy. If you intend to in-corporate fish and other water life you will need
to give serious consider-ation to site location, filtration, water pumps, oxygen ratios,
chemical use, feeding, cleaning schedules and winter care. Plan for success.
