Last week’s topic was water gardens and how to care for them. This week I’m going to touch on aquatic plants for the water garden and their function.
Just as there are many plants from which to choose for a traditional garden, there are many choices available for water gardens, too. Selection depends on what role the plants will play. Aquatic plants can broadly be categorized by where they grow relative to the water’s surface. These include submerged, surface and emergent plants.
The most obvious choice, of course, is that of a surface plant – the water lily. They’re not only popular, but beautiful, with more than 70 species that come in various colors, shapes and sizes.
Water lilies are divided into two main groups, tropical and hardy. Hardy water lilies survive our winters, while tropical water lilies must be overwintered indoors.
Tropical water lilies have many aesthetic advantages over the hardy varieties, such as larger flowers and lily pads and a greater variety of flower colors. Some varieties are night blooming. However, the hardy varieties offer plenty of beauty to the water garden and are equally graceful.
Another popular option is lotus. These majestic plants hold their leaves above the water surface and put on a beautiful floral display throughout the summer. There are many varieties of the lotus species Nelumbo nucifera commonly used in water gardens. While native to the Orient, the Philippines, northern Australia and Egypt, there also is an American native species, Nelumbo lutea, which you can see growing in Oklahoma’s natural wetlands. Lotuses are rather aggressive and can out-compete other aquatic plants for light and space. For this reason, gardeners may want to use lotus in isolated areas.
Floating aquatic plants like lotus and water lilies do a great deal to maintain the well-being of the water garden ecosystem. They shade the water, which keeps the water temperature down during the hot summer months. Their shade also gives shelter to any fish that may be in the pond. By blocking out sunlight, the lilies help to keep the algae growth down.
For a hardy native, consider Sagittaria latifolia, or arrowhead. It boasts distinctive arrow-shaped foliage reaching 2 feet to 2.5 feet in length. Apple-like blossoms are produced on long, arching stems. Another native, Thalia dealbata or hardy water canna, has a tropical look with its large canna-like foliage and purple flowers. Growing 6 feet tall or more, it is striking in a larger water garden. A number of iris take well to aquatic habitats as do rushes and sedges. These plants are found naturally along pond edges.
Submerged plants, also known as oxygenators, are a great benefit to any pond or water. They compete directly with the algae in your pond for nutrients, keeping your water garden clean and clear. Submerged pond plants do not need soil; they need to be underwater to survive. The submerged plants, similar to floating plants, continuously absorb nitrates and phosphates in the water, which are the leading nutrients that promote algae growth. They also provide great spawning media for your fish, frogs and snails.
When deciding which plants will best fit your garden, remember to do your research and make sure it is not an invasive species in our area. Check out this list of invasive species before selecting your plants.