Water Gardening Q & A

Where is the best location to place a water garden?
  • Your site should be level but not at the lowest point in the garden, where anything and everything can run into it.
  • To successfully grow Water Lilies and many other aquatics, position your water garden to receive 6-8 hours of direct sunlight per day.
  • Away from deciduous trees as roots make digging difficult and leaf drop in fall threatens fish and promotes algae.
  • At a safe distance from all underground utilities.
  • Close to patio/deck for maximum visual and auditory enjoyment.
  • Easy access to a garden hose and electricity for pump and/or lighting, if applicable.
What are the most important construction tips when installing a liner or preformed pool?
  • 2-4" of sand on the bottom so rocks/stones can't perforate.
  • Place a board and carpenter's level across the top of the pond to ensure it's absolutely level.
  • Leave a wide lip of liner at the top on which you can place flagstones and/or landscape rock to finish the edge with a natural look. Trim the excess afterward.
How do I choose which type of water garden to build?
  • If you want fish in addition to aquatic plants, you will need a depth of 3-4' to over-winter both.
  • To achieve a depth of 3-4', you will need to install flexible PVC (polyvinyl chloride) liner.
  • This choice of material allows you to build any size pond in any shape with sloped sides and shelves for "Marginal" plants.
  • PVC liner is also fish-safe, resistant to extreme temperatures, and easily repaired.
  • Preformed rigid ponds are not fish-friendly as they get too hot in the summer and are not deep enough to over-winter hardy aquatic plants.
  • Preformed ponds are less expensive, easy to install, and transportable should you decide to move.
How do I select a pump for a small water feature such as a spitter?
  • Pumps are sold based on how many gallons of water they circulate in an hour (g.p.h.). Calculate how many gallons of water are in your pond using the following formulas:
  • Rectangular or Square: length x width x depth x 7.5 = US gallons.

For example:

  • 8' x 5' x 3' x 7.5 = 900 gallons you will need a 900 g.p.h. pump minimum.
  • Circular: diameter x diameter x depth x 5.9 = US gallons.
  • Oval with straight sides: length x width x depth x 6.7 = US gallons.
What are floating aquatic plants?
  • Floaters simply drift on the water surface and move where the breeze takes them.
  • They shade water surfaces like lily pad leaves and absorb dissolved nutrients that contribute to algae proliferation.
  • 60-70% of water's surface should be covered with foliage to reduce the water temperature and combat algae growth.
  • Water Hyacinth and Water Lettuce are annual plants and particularly attractive with shiny, leathery leaves or soft green, felted foliage upon which water beads.
  • Water Hyacinth roots receive and protect fish eggs while the leaves hold spawn near the surface where their warmest but still protect spawn and baby fish from the sun.
  • After fish are hatched, they continue to be protected among the Water Hyacinth roots.
Are Water Lilies difficult to grow? How do I go about choosing one?
  • Hardy Water Lilies need a minimum of 6 hours sunlight, rich soil, and warm, shallow, unmoving water to be able to last for years.
  • They come in a range of sizes from small with a mature spread of 4-5 sq. ft. to medium spread of 6-10 sq. ft. and large at 10-12 sq. ft.
  • Blooms can be pink, white, yellow, salmon, or red and they sit just above the surface of the water.
  • To overwinter, move containers to the deepest area of the pond (at least 2"-3") so the roots don't freeze solid.
  • Tropical Water Lilies can be treated as an annual or brought indoors to a heated greenhouse or sunroom, placed in a tank where water temperature doesn't fall below 70°F, and returned to the pond when water temperature outside is 70°F (usually early June).
  • Large flowers are held above the water on long stems in shades of blue, purple, red, pink, yellow, and white.
  • Day and night blooming as well as fragrant varieties are available.
  • Tropical Water Lilies are prolific bloomers.
  • Fertilize once a month from April to August with an aquatic fertilizer pellet/pond tab that is inserted into the soil.
What are Oxygenating Plants? Do I need them?
  • Oxygenators grow under water and control algae.
  • They absorb excess nutrients from the water and liberate oxygen that clears water, prevents growth of algae, and allows fish to breathe.
  • They also provide spawning space for fish and much needed shelter and protection for baby fish.
  • Oxygenating plants include Elodea, Cabomba, Hornwort, Sagittaria, and Vallisneria.
  • Place the pots on the bottom of the pond between lily tubs.
How do I plant Aquatic Plants?
  • All aquatics can be planted in pre-mixed, rich, clay loam.
  • Do not add compost, peat moss, or manure as lighter materials float and manure discolours water and encourages algae growth.
  • Plastic mesh baskets are available in a variety of sizes.
  • Marginal or bog plants can be planted in 8-10" containers or larger.
  • Dwarf Water Lilies can be planted in 10-12" pots while most other lilies require 15-24" diameter containers.
  • Oxygenating plants can be planted in 8" containers or shallow trays.
  • After planting, top the container with heavy gravel or riverbed stone to weight the pot and prevent fish from nosing around the soil and clouding the water.
Are snails beneficial to my water garden?
  • Yes, these scavengers feed on algae.
  • Hardy Trapdoor snails can thrive for years in your pond and they bear their young fully developed so they can take care of themselves among goldfish.
  • Hardy Melantho snails consume large amounts of green scum and are prolific egg layers.

Are there water plants that I can grow near the edge of my pond?
  • With flexible PVC liner ponds you can build ledges near the edge and place pots of shallow water and bog plants.
  • These plants include winter hardy Arrowhead, Corkscrew Rush, Yellow Water Iris, Pickerel Rush, and Cattail to name a few.
  • To overwinter, trim back the foliage and drop containers to the deepest part of the pool with Water Lilies.
  • Tropical, non-hardy, shallow water plants include Taro, Canna, Papyrus, Parrot Feather, and Golden Club - they look very exotic.
What is causing the algae in my water garden and how do I prevent it from occurring?
  • Too much sunlight on surface of water: floating aquatic plants and Water Lily foliage need to cover 60-70% of surface.
  • Warm water: not enough plants on the surface to keep water cool and/or the water is too shallow.
  • Cool water: plants haven't started to grow yet because water isn't quite warm enough - be patient - wait for water to heat up and plants will do their job of covering the surface and absorbing nutrients that don't evaporate.
  • Dissolved nutrients in water: all aquatic plants absorb these nutrients instead of being food for algae - increase ratio of plants to water area.
  • Large fish population: fish waste breaks down into nitrate fertilizer and makes algae thrive - reduce number of fish, increase aquatic plants, and/or consider using a biological filter system.
  • Excessive feeding of fish: feed in smaller amounts, less often.
How many fish can I put into my pond?
  • A maximum of 1" of fish per square foot of surface area.
  • Calculate surface area by establishing square footage. i.e. length x width.
  • Allow for growth and reproduction.
  • Too many fish causes stress and makes them more disease prone.

How often should I feed the fish in my pond?
  • Feed fish a small amount twice a day.
  • They should consume it all within 3 to 5 minutes.
  • Remember, too much fish food and fish waste are contributing factors to algae proliferation.
How can I prevent raccoons and herons from getting at the fish in my pond?
  • For raccoons: edge your pond with rocks or flagstones that hang out over the water 6-8" so they can't walk into the water and place rocks high enough from water surface that they can't scoop fish out.
  • For herons: run several strands of fishing line filament in the area of the water garden (perhaps from house to trees or from tree to tree) so they won't land at all.
How do I prepare my water garden for the winter months?
  • In early autumn: stop fertilizing plants, install netting over the pond to catch leaves/needles, scoop or vacuum debris from bottom of pond, prune yellow lily leaves, bring tropical marginal plants indoors prior to last frost.
  • Late autumn: place hardy Water Lilies and tender, hardy marginals in deep, ice-free water. Leave non-tender hardy marginals on growing shelves, compost annual floaters such as Water Hyacinth and Lettuce.
  • Remove the pump from the pond and install a pond heater or bubbler to keep a small area of the pond ice-free so toxic gases that would kill fish can escape or bring fish indoors before water temperature drops to 50°F to reduce stress.