The magic of aquatic plants lies in their beauty and diversity.

When I design a water garden, I use my knowledge of a plant’s growth characteristics and cultural requirements to achieve a biologically balanced pool.

When choosing plants for your water garden, the aesthetic considerations are almost unlimited. The leaves of aquatic plants offer many varied and often dramatic shapes from arrowhead and palm-like to heart-shaped. Leaves may be waxy, smooth, ribbed, hairy or glossy, and can be shades of green, brown, purple, yellow, or variegated. Many aquatic plants such as the water Canna (Thalia spp.) and the ornamental rice plant (Zizania latifolia) persist into fall and through winter. The hues of their foliage and flowers gradually change as fall draws near.

A plant’s flowering characteristics and sequence are very important when designing your garden. First you’ll want to consider the colors you’d like to see. I always take into account when the garden most likely will be used, despite the fact that a garden should provide four-seasonal interest. You may want to include some aquatics whose flowers are fragrant. The placement of these plants should be prominent since their fragrance is often subtle.

The same design principles you follow for your landscape should also apply to plantings for water features. A plant’s shape, size and its relation to the garden and surrounding landscape are all equally important as is incorporating varying plant heights. For example, the flat leaves of lilies floating on the water’s surface and the lotuses’ slightly raised flower heads accentuate the horizontal plane. I like to juxtapose vertical varieties using bulrushes and dwarf cat-tails in my water features.

Sunken water garden that includes iris and cat-tails, floating hyacinths, parrot’s feather and arrowhead.

One should also take into consideration a plant’s root growth and potential spreading characteristics. I like to plant vigorously spreading plants together and let them battle it out for territory! Delicate, less aggressive plants ought to be separated from other plants or planted in containers.

The quantity of plants to be included in or surrounding your water feature is determined by the type of plants chosen, their respective growth rates and the amount of time you have to spend on their care. The recommendation for including plants within a water feature is typically one-third to two-thirds of the water’s surface. This ratio will allow for some shade should you decide to add Koi or gold fish in your feature. Additionally, “planting” two-thirds of the water’s surface will control algae, keep water temperatures down and help keep your fish healthy. Most clients gasp when I suggest the “two-thirds” ratio for their feature. But remember: this is a water garden. And gardens, generally, are comprised mostly of plants.

Plants should be chosen by one’s taste and, more often than not, according to one’s time schedule. Be willing to experiment with new varieties and to trade plants with friends who also have water gardens. A water garden, like any living organism, constantly changes and evolves. It will not look the same from season to season or year to year. Change is a part of a garden’s many pleasures!

The types of aquatic plants can be divided into four categories as follows:

Marginals:
These are edge plants that thrive with zero to 12 inches of water over the crown of the root system. Marginals prefer moist to wet soils or the shallow edges. In nature, marginals create the transition between land and water.

Bog or Moisture Tolerant:
These plants prefer soils in which the root crown is at or slightly above the water level. Bog plants do not like to be completely submerged for extended periods of time. They are most common to moist meadows with about five to six hours of full sun daily.

Oxygenating Plants:
These plants grow on the bottom of the water garden in one to four feet of water. Oxygenating plants are the most beneficial because they cleanse the water by removing salts and other impurities. They tend to out-compete algae for nutrients and increase the available oxygen supply to fish; hence the name “oxygenating.”

Floating Aquatics:
All water lilies, lotus and non-oxygenating plants are listed under this category. Floating aquatics generally produce roots at a depth of one to three feet below the water’s surface.

Aquatic plants greatly add to the life and beauty of any water feature. Their inclusion will attract beneficial insects, birds and butterflies not only to your water garden, but also to other areas of your landscape or gardens as well.

Let us not neglect the practical reasons for including aquatic plants: They shade the water surface, thereby discouraging algae; they stabilize pond banks; they provide food and shelter for various bird species; and they create the necessary ecological balance for your feature. Last but not least, aquatic plants provide the most extraordinary color and interest all through the seasons.

Traditional Cat-Tail growing along a farm pond.

Dwarf cat-tail species amongst hardy water lilies.

Japanese iris species

Close-up of water lily foliage.

Some suggested aquatic plants: botanical name followed by the common name.

Marginals
Acorus calamus – Sweet flag
Calla palustris – Arum
Caltha palustris – Marsh marigold
Iris kaempferi – Japanese iris
Iris pseudocorus – Yellow (native) iris
Iris siberica – Siberian iris
Pistia stratiotes – Water lettuce
Pontederia cordata – Pickerel
Sagittaria spp. – Arrowhead
Scirpus lacustris – Bulrush
Thalia dealbata – Water canna
Typha angustifolia – Cat-tail (narrow-leaved)

Bog or Moisture Tolerant
Asclepias incarnata – Milkweed
Aster macrophyllus – Bigleaf aster
Carex spp. – Carex
Chelone lyonii – Pink Turtlehead
Eupatorium purpureum – Joe-Pye weed
Helinathus angustifolius – Swamp sunflower
Hibiscus moscheutos – Rose mallow
Lobelia cardinalis – Red cardinal flower
Petasites japonicus – Japanese butterbur
Vernonia novaboracensis – Ironweed

Oxygenating Plants
Elodia canadensis – Pondweed
Myriophyllum aquaticum – Parrot’s feather
Ranunculus aquatilis – Water crowsfoot

Floating Aquatics
Nelumbo spp. – Lotus
Nuphar luteum – Pond lily
Nymphaea spp. – Hardy and Tropical water lily
Nymphoides peltata – Miniature pond lily