Plant Care

Planting Aquatic Plants

Black Gamecock Iris


All aquatic plants should preferably be planted in rich clay based topsoil. Try to avoid a soil with a lot of compost or peat, as the lighter materials tend to float. Most commercially bagged and sterilized soil is not suitable for aquatic plants because they contain these materials. Aquatic soil developed specifically for water plants is normally available from your local garden centre.


Plastic containers are recommended because they are sturdy yet light in weight. Marginal or bog plants can be planted in any suitable container, usually 8 to 10” across, but the bigger the better. Keep in mind that aquatic plants will grow proportionately to the size of the container in which they are planted. Too small containers will slow their growth by allowing them to become overcrowded quickly. For more stability, use wide base pots for tall, emergent plants. Most water lilies require large containers from 15” to 24” across, with a capacity of 27 liter (¾ bu.) of soil per lily or larger, dwarf varieties can be planted in 10” to 12” pots, but at least an 18 liter (1/2 bu.) container is recommended. Lotus require at least a 27 liter container but prefer larger containers with rounded corners. Even dwarf Lotus need at least a 27 liter container. Use 8” pots or shallow trays for planting oxygenating plants.

Planting Oxygenating Plants


Oxygenating plants should be planted in moist soil in their own pots. An 8” pot is large enough to accommodate one bag of oxygenating plants. Remove oxygenating cuttings from the mesh bag and tuck half the plant stem into the
moistened soil. Bury the root system of the individual plants in the soil. Leave the soil level about 1” below the top of the pot and fill the remaining space with gravel. Soak the soil with pond water to prevent muddying up the water when the plants are placed in the pond. Place pots directly on the bottom of the pond between the lily tubs. The rule of thumb is to use 1 bag of oxygenating plants for every 5 – 6 sq ft of open surface area (less for large ponds).

Note: Hornwort does NOT need to be planted, it floats in the pond.

Transplanting Hardy and Tropical Water Lilies

Transplanting Potted Hardy and Tropical Water Lilies

Potted hardy lilies can be transplanted into larger containers until September. Transplant tropical lilies in June when the water temperature has warmed to above 20 degrees C. Cold water will cause the young plants to become dormant. Tropical lilies and hardy lilies must be transplanted from their original pots to an 18 – 27 liter container or larger. If left in the original container, the lily will become pot bound, which will stunt their growth. Therefore, a large container allows enough room to grow, so that your lily will grow to its full potential and bloom frequently. Fill the large container half full of moistened, tamped down soil. If using an organic fertilizer, add a mixture of fertilizer and soil. Carefully remove the original pot from the lily and place the lily (soil and all) into the centre of the large container. Fill the remaining space with moist soil leaving about 1 inch from the top of the pot. Tamp soil down gently. If using fertilizer tablets, put 8 tablets around the pot and cover with soil. Cover soil with a layer of gravel, making sure that there is NO SOIL OR GRAVEL ON THE CROWN. The gravel will help reduce the amount of soil stirred up and discoloring the water and also helps discourage the fish from uprooting the plants. It is a good idea to soak the soil with some warm pond water before placing the containers in the pond to reduce the amount of muddying of the pond. Using aquatic soil also significantly reduces muddying the pond. Water lilies are heavy feeders and should be fertilized with 4 fertilizer tablets once a month from April to August for maximum bloom and growth.

Positioning Your Lilies

Position your lilies in the middle of the pond about 5 – 6 feet apart. Initially, it is best to have the lilies at the shallower depth (approximately 6 inches of water) and then gradually move them deeper as the lily grows. You may need blocks to raise the lilies to the proper depth. Water lilies will grow in 6 inches up to 3 feet of water, depending on the variety. Do not place water lilies close to waterfalls or fountains where they will be splashed.

Transplanting Hardy and Tropical Shallow Water Plants

Longwood Endeavour Canna

Transplanting Potted Shallow Water Plants

Potted plants may be transplanted at any time. Half fill an 8” pot, or larger, with moistened tamped soil. Carefully remove the original pot from the plant and place the plant (soil and all) into the centre of the pot. Fill the remaining space with moist soil leaving about 1 inch from the top of the pot. Tamp soil down gently. Cover soil with a layer of gravel, leaving the crown of the plant protruding. The gravel will keep the soil from being stirred up and discoloring the water and also prevents the fish from uprooting the plants. Soak the soil with some warm pond water before placing the containers in the pond to avoid muddying up your pond water. Fertilize monthly to encourage growth and bloom with either 10-26-10 or 20-5-10 AgriTabs Aquatic Fertilizer.

Positioning Shallow Water Plants

Marginal plants are often situated on pond shelves; adjustments may be required for proper depth. See individual plant descriptions for proper planting depth. If shelves are full, try using blocks or inverted pots to position plants at proper depth anywhere in the pond.


Directions for Fertilizer Tablets

Use 8 to 10 tablets of AgriTabs 10-26-10 fertilizer tablets per lily or lotus container in the spring or when first planting. Use 3 tablets per 8” pot for shallow water plants. Your lilies should be fertilized monthly with 4 tablets per lily container and 1 – 2 tablets per 8” pot for shallow water plants. Be sure to keep the tablets a few inches away from the crown of the plant to prevent burning. Push the fertilizer tablet as far down as you can with your finger. Then fill in the holes with soil to prevent the fertilizer from leaching into the water. Do not fertilize hardy plants after mid August.

Directions for Organic Fertilizer

Organic fertilizer is best used for initial and spring planting. Mix 1/8 Kg of organic fertilizer per 18 liters of soil. Place soil/fertilizer mixture in bottom ½ to ¾ of the container, and then fill the rest with moistened soil.

Lotus ‘Mrs. Perry D. Slocum’

Overwintering Your Plants

Hardy plants are perennials and can be kept for many years. Some varieties may require additional protection due to differences in your zone and actual microclimate of your pond. Plant Hardiness Zones in Saskatchewan range from 1 in the north of the province to 4 in the south. For more information on Hardiness Zones visit the website of Natural Resources Canada at:

Hardy Water Lilies and Lotus

Hardy water lilies and lotus will overwinter if their roots do not freeze solid. Foliage will die back mid to late fall but the roots will remain alive. Steps to overwinter lilies and lotus should be taken at this time. DO NOT COVER the pond or bring plants inside until late fall when dormancy has begun.

There are two commonly used methods to overwinter hardy water lilies:

  1. In pond storage

    Remove any dead leaves on lilies, but not on the lotus, and move the plant containers to the deepest area of the pond and lower them to the bottom of the pond. It is recommended that your pond be 11/2 to 3 feet deep in the deepest area if this method is chosen. Colder zones may need to increase this depth or use increased protection methods such as covering the pond with boards or framed plastic to provide extra insulation. However, it is important not to make the pond cover airtight. Return plant containers to their original positions in the spring. If you have any fish remaining in your pond it is important to keep an open area of water in the ice so that there can continue to be a gas exchange over the winter.

  2. Indoor storage

    Use this method if your pond is shallow and will likely freeze solid. Remove the old leaves from the lily and bring the planted container indoors and store in a cool area, around 5 degrees C., for the winter. Keep containers moist and dark at all times. More lilies are lost from drying out than freezing. Return plant containers to their original positions in the pond after the ice has melted in the spring.

Hardy Shallow Water Plants

Some hardy shallow water plants can tolerate being frozen solid while others need their roots or tubers to remain in the water. Irises, Rushes (except Pickerel Rush), Sweet Flag, Cattails, Horsetail, Marsh Marigold Bulrush, Houttuynia. Golden Creeping Jenny and Buttercup, Watercress and Water Forget-Me-Not may be left in shallow water where they will likely freeze. Most other varieties should be moved to deep water or bought indoors to cold storage – see method 2 above. Return all plants to the growing shelves as soon as the ice has melted in the spring.

Note: Do not remove the dead leaf stocks from emergent plants such as cattails and rushes until spring. This will allow the root systems to “breathe” during the winter.

Tropical Plants

Although tropical plants may be grown in our climate during the summer, they are considered annuals unless a heated greenhouse or similar facility is available.

Tropical Water Lilies

When brought indoors, tropical water lilies and plants continue to grow during the winter months and must receive sunlight and heat. Growth slows considerably in December and January when there is very little sunlight and the leaves will become yellow and small. Most people treat tropical water lilies as annuals due to the considerable effort required for their continual growth.

If you wish to try and overwinter your tropical water lily you can try the following method. Before the first heavy frost in your area, bring the tropical water lily indoors to a heated greenhouse or sunroom. Place the container in a tank, fertilize sparingly and ensure that the water temperature does not fall below 20 degrees C. This will prevent the lily from going into a dormant state even though growth slows considerably. The following spring when the pond water temperature has warmed to a consistent 20 degree C temperature, in early June, place the lily back in your pond.

Tropical Shallow Water Plants

Like tropical water lilies, tropical shallow water plants must continue to grow during the winter months. Growth will be reduced considerably as daylight hours diminish. Umbrella Palm, Dwarf Papyrus, Little Giant Papyrus and White Arum lilies will survive the winter indoors and make excellent houseplants. Other varieties are best treated as annuals.

If you wish to try overwintering your tropical shallow water plants not listed above you can try the following method. Remove the tropical plants from the pond before the first severe frost and bring indoors to a heated greenhouse or sunroom. Plants must remain in water and be kept at a temperature of approximately 18 degrees C. Remove old growth if it yellows. Return to the pond in the spring when there is no risk of frost and the ice on the pond has melted.

Note: Small amounts of fertilizer may be required to encourage the plants to keep growing during the winter.

Many people treat Tropical Shallow Water Plants as annuals due to the cost and effort to overwinter. Simply compost plants in the fall and restock the pond the following spring. Water gardeners in Canada frequently use the previous overwintering methods for plants. These suggestions can be used alone or in any combination to best suit your own situation. There is no guarantee that your plants will survive the winter.


Algae Problems

Both newly planted ponds, as well as established ponds, provide ideal conditions early in the season for the growth of suspended algae, causing green, murky water. This is a completely natural occurrence and is not harmful to plants or fish.

Contributing Factors:

  • Sunlight – inadequate plant growth to provide sufficient shade.
  • Warm water – resulting from inadequate plant cover and/or shallow water
  • Dissolved nutrients – present in the water, providing food upon which the algae thrives
  • A large fish population – fish waste is eventually broken down into nitrate fertilizer
  • Excessive feeding of fish – unconsumed fish food and excess fish waste


  • Be Patient – allow the pond time to achieve a natural ecological balance between plant life, nutrients, light and temperature. Once the plants start to grow, they will filter the sunlight, thus providing shade and lowering water temperature. In addition, these plants will consume excess nutrients in the water, thus depriving the algae of food.
  • Do not change the water – this merely provides a fresh supply of dissolved minerals for the algae to feed upon and thus prolongs the time for a natural clearing to take place. Further, sudden temperature changes place stress upon the plants and fish.
  • Do not add algaecides – this will create artificially clear water, which may become green again as the chemicals lose their effectiveness. Most importantly, any chemical that will kill algae, a simple form of plant life, is likely to hinder the growth of more desirable aquatics such as lilies and marginal plants. Improper dosage can result in the loss of all plants and even fish. If coagulants are used to settle suspended algae, filtration is usually necessary to remove coagulated plant material before its decomposition can harm fish.
  • String algae – is sometimes a problem in mature, balanced ponds with clear water. A small amount is beneficial in keeping water clear and providing natural food for the fish. Excessive amounts can be removed manually or by gently altering the pond chemistry to create conditions unfavorable to the growth of string algae. Barley straw and peat pellets are natural products recommended for that purpose. .
  • Be sure you have sufficient plants for a balanced pond – oxygenating plants do a great deal to absorb dissolved nutrients. We recommend 1 bag for every 5 – 6 square feet of exposed surface area. Larger, deeper ponds require less. Add water hyacinths or another water lily to provide shade and use up nutrients. Hyacinths are inexpensive and usually multiple rapidly. Other floating plants such as salvinia and duckweed are also very helpful. A good supply of snails and/or a vacuum will help to remove slime and accumulated debris, thus helping to keep the water clear. If the fish population is large, especially Koi, a filter may be needed. We firmly believe that an ecologically balanced pond will provide more profuse growth and bloom, thus giving the water gardener more pleasure and satisfaction for his efforts. “Plant for balance” be patient and prepare to sit back and enjoy a summer full of healthy, exotic flowers and lively fish.

Water Lilly Problems

  • The use of chemicals to control algae is not recommended.
  • Planting containers are too small
  • Lilies are not getting enough sunlight – depending on variety they need 6 hours minimum
  • When planting did not use heavy topsoil and/or fertilizer as recommended.
  • Many commercially packaged soil mixtures are not suitable for water lilies
  • Soil or gravel on the crown of the plant
  • Needs fertilizer – did not fertilize monthly with 10-26-10 fertilizer
  • Root bound – hardy water lilies need dividing every two or three years
  • Too little or too much water over the crown
  • Hardy water lilies start to go dormant in September.
  • Tropical lilies do poorly in cold weather and go dormant after a heavy frost.
  • Use of herbicides or pesticides in your yard or your neighbor’s
  • Splashing or turbulence from nearby fountain or waterfall
  • Large koi or goldfish may be eating new growth and possibly disturbing the root system.
  • Excess of aphids, which may be sprayed off with a hose and eaten by fish.