Aquatic plants are an essential aspect of the pond’s ecosystem. Finding the right combination will increase the clarity of the water, deter algae growth and provide visual interest in and around the pond. There are four different classifications of water plants; excluding water lilies (which can be found in its own brochure entitled ‘Water Lilies’): deep water marginals, marginals, floaters and oxygenators. A general rule of thumb, to discourage algae growth, is to have 70% of the surface of the pond covered by floating plant material. This includes floaters, deep marginals or water lilies. Water plants will help maintain the ponds ecosystem and adds colour and texture to your water element.
Deep water marginals
Deep water marginals are similar to water lilies in that they have a root ball rooted in the bottom of the pond and leaves floating on the surface. These plants prefer to have at least 4-6” of water over the soil. When introducing a deep marginal into a pond make sure the leaves always remain on the surface of the water. As the plant grows they can be dropped deeper. However, if there are buds, lowering the plant will cause them to fall off.
1 DEEP MARGINAL PER SQUARE METER
Water Clover - Marsilea quadrifolia (ZONE 6)
Planting depth: 4 in or 1 ft, Marginal Shelf. Comments: Prefers 70ºF temperature.
Water Hawthorne - Aponogeton distachyos (ZONE 4)
Planting depth: 1 to 2 feet Comments: Prefers a shady location. Very prolific bloomer.
Water Poppy - Hydrocleys nymphoides (ZONE 6)
Planting depth: 6 in to 1 ft, Marginal Shelf. Comments: Require full sun and 70ºF to bloom.
These plants will over-winter in cold storage or under ice providing the pond is 1.2 meters deep. For cold storage, remove pot from pond and allow draining for a few hours. Soil should be damp but not muddy or completely dry. Trim back foliage to 1-2” above the crown. Place plant and all in a plastic tub with a tight fitting lid. Or wrap pot in burlap and place it in a plastic bag and loosely tie. Keep it in cold storage at a temperature between 1 to 5 ºC. Check monthly to ensure the root system is sufficiently moist.
This is the largest group of pond plants used around the outside of the pond on a Marginal Shelf. They require 2 to 6” of water over the soil. Some varieties will survive in marsh-like soil around the edge of the pond. Use this group to act as a wind-breaker and to add texture to your water garden.
Arrow Grass - Triglochin sp. ZONE 2
Comment: Non-invasive. Cylindrical foliage that tapers to a point.
Arrowhead - Sagittaria lancifolia, S. lancifolia ‘Red-stem’, S. latifolia, S. sagittifolia ZONE 2
Comment: Very prolific. Popular for our climate.
Cattail - Typha latifolia, T.laxmanii ZONE 2
Comment: Common & dwarf varieties. Wind breaker.
Colt’s Foot - Petasites sagittatus ZONE 2
Comment: Flowers before it leafs out.
Creeping Spike Rush - Eleocharis palustris ZONE 2
Comment: Vigorous, wind breaker, large foliage.
Flowering Rush - Botomus umbrellatus ZONE 5
Comment: Stake when first planted. Vigorous.
Golden Button - Cotula coronopifolia ZONE 6
Comment: Somewhat invasive. Long blooming.
Horsetail Rush - Equisetum hyemale ZONE 2
Comment: Alternating bands of green & brown.
Juncus - Juncus ensofolius ZONE 5
Comment: Strong foliage.
Lizard’s Tail - Saurus cernus ZONE 4
Comment: Flowers curl at the end, looks like a lizard’s tail.
Marsh Marigold - Caltha palustrus ZONE 2
Comment: Likes acidic soil & shady location.
Needle Spike Rush - Eleocharis acicularis ZONE 2
Parrot’s Feather - Myriophyllum aquaticum ZONE 6
Comment: Great next to a waterfall or in baskets
Pennywort - Hydrocotyl ranunculoides ZONE 5
Comment: Aggressive growth, nice foliage.
Pickerel Weed - Pontederia cordata ZONE 3
Comment: Ice under water. Native to Manitoba.
Spike Rush - Eleocharis palusris ZONE 8
Sweet Flag Iris - Acorus calamus, A. calamus “variegata” ZONE 3
Comment: Vigorous once rooted. Wind breaker.
Umbrella Plant - Cyperus alternifolius ZONE 6
Comment: Looks best at temperatures of 70ºF.
Yellow Flag Iris - Iris pseudocorus, Iris pseudocorus “Variegata” ZONE 2
Comment: Strong foliage and winters well.
Water Plantian - Alisma plantago aquatica ZONE 3
Comment: Striking foliage. Easy to maintain.
Water Sedge - Carex aquatilis ZONE 2
Comment: Hardy native. Resists wind damage.
Zebra Rush - Scripus zebrinus ZONE 2
Comment: Cylindrical stems stripped in green and white.
Hardy marginals can be left on the marginal shelf in the pond year round. Or sink the pot into your garden and back-fill with soil. Dig out and re-introduce into the pond once frosts have passed. Tropicals should be wintered indoors same as Deep Marginal Plants.
As was stated before, 70% of the pond’s surface should be covered to prevent algae growth. Floaters are ideal solutions as the easy to grow. They do not need a pot or soil as they float on the surface of the watery are relatively inexpensive and very. Do not worry about fertilizing them because they will filter enough nutrients directly from the water.
1 FLOATER PER SQUARE METER.
Duck Weed - Lemna minor ZONE 2
Comments: Good for fish, very invasive.
Fairy Moss - Azolla caroliniana ZONE 5
Comments: Turns red when temperature drops.
Frogbit - Limnobium spongia ZONE 6
Comments: Leaves are shiny on upper surface and have a spongy underside.
Water Hyacinth - Eichomia crassioes ZONE 7
Comments: Inexpensive and fast-growing
Water Lettuce - Pistia stratiotes ZONE 7
Comments: Prefers rain water with little fertilizer.
Frogbit will sink to the bottom of the pond to over-winter. Others can be wintered indoors in an aquarium or a pool with 5-6 hours of light per day. Otherwise discard floaters after they’ve been hit with frost. Re-introduce back into pond after frosts have passed and pond temperature has reached 60ºF.
Oxygenators keep the water pure, clear and control algae naturally. They are typically sold as bunches of unrooted cuttings fastened by a metal strip. Either leave them at the bottom of the pond or bury the lead weight in soil. Otherwise the stems may rot away and the plants will float to the surface.
If you plan to have fish oxygenators provide oxygen, consume carbon dioxide and indirectly consume fish waste. To provide additional gas exchange use an electrical aeration device.
3 OXYGENATORS PER SQUARE METER.
Anacharia - Elodea canadensis ZONE 2
Hornwort - Ceratophyllum demersum ZONE 2
N/A - Sagitarria chilensis ZONE 6
All varieties will over-winter under ice providing the pond is deep enough to prevent the bottom from freezing (1.2 m). Make sure the plants are on the bottom of the pond. An alternate method is to keep them in an aquarium.