When you get your pond plants, keep them cool and shaded until you are ready to put the plants away. Do not expose them to air or sunlight before you are prepared to deal with them. Water lilies and similar plants such as water fringe and water poppy will dry out quickly. If purchased bare root, it is best to pot them immediately. Otherwise, some exposed leaves and stems are likely to dry out and die, even if they are being floated in the pond. Plants which grow with their leaves out of water may need shielding from hot sun for a few days while they adjust to root loss during transplanting. Gentle mechanical sprinkling may assist during adjustment. Water lettuce and hyacinths may also need adjusting after shipping or transport by starting them in partial shade and slowly exposing them to full sun again.
Most pond plants prefer full sun once established – the more sun they get, the better they will do and the more they will bloom. In very hot climates, some varieties may benefit from partial shade.
Plants should be potted in Professional Aquatic Potting Soil. You can also use good garden soil, loam or clay. Be careful to select soil that doesn’t have much organic matter in it as this will decay causing odors and algae blooms. Definitely do not use any houseplant potting mixture, as most of the ingredients will float. Water loosens the soil considerably and many pond plants are buoyant, so pack the soil firmly around the plant. Fill to 2″ from the top of the pot. Adding 1″ of gravel or rock on top will help keep the planting media in, especially around large fish which like to dig in soil. Lower the pot into the water slowly, giving the water a chance to displace the air without disturbing the soil.
Use a 4″ to 6″ wide pot for smaller aquatics, such as water clover, fringe, or poppy. Use a 6″ to 18″ wide for arrowhead, iris, pickerel, etc. Water lilies should have as large a pot as their roots can use, eventually up to 5 gallons of soil for large plants. If any plant has insufficient roots to permeate most of the soil in a few weeks, it is better to start it off in a smaller pot and move it up in pot size as it grows, just as with a house plant. The roots aerate the soil and help prevent the growth of anaerobic bacteria, which produce toxic byproducts inhibiting plant growth. Shallow and wide containers are preferable to narrow and deep containers, giving more room for expansion. Pots without holes in the bottom are best, as they help keep soil, fertilizer, and roots inside the pot where they belong.
Most plants can be centered in their pots. If a plant has a rhizome or tuber, such as iris, pickerel, or hardy water lilies, place the back of the rhizome at the edge of the pot, and the front (the growing tip) toward the center of the pot. This allows the rhizome more room to grow horizontally across the pot.
TROPICAL WATER LILIES: Plant outdoors after the water temperature remains 65°F or more, late May or early June for most of the country. Setting the plant outdoors any earlier will shock it and delay growth. Pot into a container sized appropriately for the root system. Up to a point, the ultimate size of the plant will depend upon the size of the container, although a 2 gallon pot will grow a nice sized plant. Use soil and fertilizer as for hardy lilies, except use 2 to 3 times as much fertilizer once plants are established and in active growth. Pots may be as shallow as 3″ underwater or as deep as 18″, with around 8″ being a good average. Shallower plantings will result in faster growth due to warmer surface water. Plant tropical lilies in the center of the pot. To actively winter over, keep in a heated greenhouse. To store the tubers, wait until the plants have started to die back for the winter. Cut leaf stems and roots from tuber, and rinse well. Soak briefly in a mild fungicide solution if available, then store in clean, barely damp sand in a cool place, preferably around 40°F. Begin growth in spring in warm shallow water under good light; wait until pond has warmed up to place outside. Tropical lilies bloom profusely, far more than hardy lilies and for longer in the fall.
LOTUS: Lotus tubers are banana-like in shape. Handle carefully, as the growing tip is easily damaged. Use shallow and wide containers of 5 to 25 gallon capacity for all but dwarf varieties. Place tuber almost horizontal so that the end of the tuber is about 2 inches under the soil, and the growing tip is barely exposed. A small stone may need to be placed gently on the soil over the buoyant tuber to hold it down while rooting. Position tuber end against the pot edge and the growing tip toward the center. Place pot 2″ to 4″ under water surface. Once the lotus is growing well, it may be placed up to 12″ or even more under water. When lotus is established and growing actively, fertilize heavily, two to four times as much as for hardy water lilies. Once foliage has browned in the fall, lower pot to below freezing level. Lotus grows superbly above ground in cured whisky barrels, but do not allow the barrel to freeze solid during the winter.
MOVING WATER: Moving water such as fountains, streams, and waterfalls is not necessary for fish or plants. It does enhance the attractiveness of the pond, helps control algae slightly, and increases the oxygen level, which means you can have more fish. You can also use the pump to operate a filter of some sort, which helps the pond stay cleaner and support still more fish.
FERTILIZING: Follow the instructions provided with your water plant fertilizer. Use a tablet rather than a liquid fertilizer unless there is very heavy plant cover or unless you are specifically fertilizing floating plants (heavy plant cover prevents algae from getting too much of the liquid fertilizer). Fertilize most plants once a month during the active growing season, generally beginning in April. Plants requiring heavy feeding, such as tropical water lilies and lotus, benefit from extra fertilizing. Stop fertilizing in August. This allows the plants to use up most of the fertilizer and start preparing for winter.
WATER DEPTH: Water lilies vary in their tolerance to deep water, but all will thrive in water 8″ to 24″ deep from the top of the pot. Most will grow in water 3 to 5 feet deep, and some even deeper. Start by placing the lily in shallower water, and gradually move it deeper as it adjusts. Most pond plants which grow up out of the water will live in moist soil or underwater up to 6″ deep. Keep small bog plants shallower, while tall ones, such as mature yellow flag iris, can live in water a foot or more deep.
ALGAE CONTROL: The best way to control algae is the natural way, with plants and scavengers. Plants are by far the most important, as they compete with the algae for light and nutrients. Water lilies, water hyacinths, water lettuce, fairy moss, anacharis, and the Nymphoides are the most effective because of their superior covering action and/or their rapid nutrient-absorbing growth. We recommend covering about half the pond surface with plants, leaving plenty of surface for viewing fish. Japanese trapdoor snails will help control algae if used in addition to plants, and will also eat leftover fish food. In the spring the pond is likely to have an algae “bloom”, with obviously green water. As plants start to come up and cover the water surface the algae should die back. If you have an algae problem, don’t expect immediate relief with plants and snails, as algae control is a gradual process. Algaecides can provide immediate relief, but the effect is very temporary, and most are harmful to plants and stressful to fish. A blue dye (known as Aquashade or Blue Water Tablets) is available, which does not harm fish, plants, or wildlife, but blocks sunlight to the algae, thus killing it. This is useful for ponds with insufficient plants, or for treatment in spring before the plants are up. Moving water, such as a recirculating waterfall or stream, helps somewhat. A good pond filter will also help, but only a diatom or fine sand filter will physically filter out free-floating algae without a using a flocculent (such as Laguna green water clarifier), and a fine particle filter requires frequent maintenance. If you want to control algae with a filter, consider a UV sterilizer. Some people feel it is worth the small cost of constantly running just a tiny trickle of water into the pond and letting it overflow. This generally creates enough turnover to keep the pond water clear. It also creates a wet soil condition around the pond wherever the water overflows, which is a great place to plant iris, lilies, ferns, or just about any shallow water plant.
MOSQUITO CONTROL: Any small to medium sized fish will eat mosquito larvae, the most popular being Gambusia (mosquitofish), goldfish, and small koi.
APHID CONTROL: There are several soap-based natural sprays available which are relatively non-toxic, and are somewhat effective. Volck® dormant fruit tree oil will often smother aphids if sprayed on them; wash off leaves in 2 hours. Malathion or diazinon spray is very effective, and is also, unfortunately, toxic to fish and other animals – however, many pond owners use it without any problems by being careful not to over use it. One suggestion when using any aphid spray is to hose down the plants first with a strong spray from a garden hose, starting at one end of the pond and moving across the pond to the other end, with the intent of washing all the aphids down to one end of the pond. They will then climb out onto the plants in a small area, which minimizes use of the pesticide. Spray late in the day to help avoid “burn” spots on some plants; use a wettable powder rather than liquid concentrates, which have petroleum distillates.
OVERWINTERING: Remove tropical plants before the first frost. Most will winter over indoors as house plants if given adequate light. Place all other pots well below the freezing level for the winter. Many plants not rated for a colder zone will survive if overwintered at a great enough depth, or if a pond heater/deicer is used. A bird bath deicer may be used to keep whiskey barrels from freezing in the winter, and will act as a bird bath at the same time. It is all right to trim off any dead or dying leaves for the winter except for some marginal uprights, especially cattail. For adequate aeration of the rhizome, cattails, Arundo, canna, and water chestnut should have their old growth left intact until new growth has come up the following spring. True cannas do best if cut back and overwintered out of water in a frost-free place like a garage.
ANIMAL PESTS: If you are having problems with raccoons, dogs, or cats, we recommend a small animal electric fence (not a big livestock unit). They are unobtrusive and work quite well. You can put it on a timer or photo-sensitive cell to work only at night. Use small wire no more than 18″ off the ground, and thread it through drilled clear plastic rods for best appearance. Ponds 3 or more feet deep with straight sides are some protection against raccoons and fish-eating birds.