By Mary Gutierrez
Your water garden is complete: The liner is
installed,
stonework finished and a nice selection of water lilies and marginal plants
have been artfully placed. There's just one thing missing, that garnish that
will complete the picture-a few lovely floating plants.
In addition to being beautiful,
"floaters" are
as low-maintenance as you can get. They don't require repotting, fertilizing or
clipping to remove dead flowers and leaves. In the Pacific Northwest, most
floaters are annuals, so your greatest effort will be purchasing a few to drop
in the pond each spring.
Besides adding beauty, floating plants perform an
important function in the ecology of your water garden. Their roots remove
nitrogen from the water, which is important if you have fish. They shade the
water's surface which prevents algae growth. They offer fish a place to hide
from predators and to lay their eggs. And young fry can swim in the shelter of
floaters to avoid being eaten by larger fish.
Floaters are so-called because-obviously-they
live on the
surface of the water and don't have roots that are anchored in soil. The are
able to do this because they have adapted unique strategies that allow them to
float. Many floating plants have spongy, air-filled sacs; others have waxy or
hairy surfaces that repel water or use the water's surface tension to remain
suspended.
In springtime, wait until your water has warmed up before
buying new floaters. Water below 65° F may cause leaves to yellow and plants
will limp along or die. In fall, most people let their floaters die off. It is
a lot of work to successfully overwinter them indoors. Floating plants make
great compost or mulch, so use them elsewhere in the garden at the end of the
season.
Because most floaters are tropical plants, many are
invasive in areas with warm climates. Water hyacinth and water lettuce are
banned in southern states because they clog waterways with their abundant
growth. Never dump or place any non-native water plants in natural bodies of
water.
Selecting floaters
In small ponds and large
container water gardens, the
bigger species will flourish. There are also a number of small floaters that
can beautify the tiniest container garden. Visit a water garden specialty
nursery in late spring for the best selection of floating plants. Many
nurseries have large ponds on-site, giving you the opportunity to see different
floating plants in real growing conditions.
Water Hyacinth
Not
a true hyacinth-of course-but the species Eichornia crassipes,
has a lovely flower in summer that gives it its common name. It has shiny,
spongy leaves with an inflated bulb at the base. Water hyacinth wants full sun
in order to grow and bloom well. This plant is invasive in many states, so
never dispose of it in waterways or introduce it into natural lakes or ponds.
Water
Lettuce
Water lettuce, Pistia stratiotes, is one of the larger floaters.
Its interest is provided by its foliage, not its flower. The leaves of water
lettuce are thick, fuzzy, and crinkled with ruffled edges, growing in a rosette
resembling a bunch of leaf lettuce. In long-summer areas, the species can reach
12 inches in height. For us, the leaves may be between two and six inches in
length because of our cooler weather and because most of the cultivars
available at nurseries are smaller than the species.
Water Sensitive Plant
This member of the pea family looks like many of its
earthbound cousins, with feathery, pinnately compound leaves-picture a locust
tree, or Albizia julibrissin foliage that floats. There are two different
genera sold as water sensitive plants: Neptunia aquatica is the smaller of the
two, with yellow tufts of flowers that resemble an acacia. The giant water
sensitive plant is Aeschynomene fluitans, which has yellow pea-like flowers.
Both of these plants share the characteristic leaves that fold together when
touched.
Frogbit
Frogbit, Hydrocharis morsus-ranae,
is a small-leaved
plant with shiny, heart-shaped leaves and dainty white flowers that look like
tiny poppies. Frogbit is good for small water gardens and container gardens in
sun to part shade.
Duckweed
Plants in the genus
Lemna-known as duckweed-are among the
world's smallest flowering plants. Duckweed forms colonies that congregate
among the stems of marginal plants. This North American native is a food source
for-you guessed it-ducks and other waterfowl as well as fish. Some people add
duckweed to the pond not for its ornamental value, but as a food source for koi
and goldfish.
Salvinia
Plants in this genus are
commonly called cat's tongue
because of the coarse texture of the hairs on the upper surface of the leaf.
Salvinias are true ferns, whose opposite leaves grow along a central floating
stem. One species, Salvinia molesta, is one of the world's most destructive
invasive aquatic plants, and is prohibited in the US. You'll look for Salvinia
longifolia, with its two- to three-inch-long furry leaves to grow in your pond.
If you have koi, you'll find that this plant is a delicacy to them!
Azolla
Azolla is an aquatic plant that fixes nitrogen from the
air, providing nutrients that other plants can use. This makes it a good
compost or mulch. You'll have plenty to go around, because it multiplies so
rapidly that water gardens can rapidly become choked with azolla. Most people
will want to avoid this plant, as it's difficult to eliminate once it is
established. Not an ideal plant for a low-maintenance water feature.
Enjoy accenting
your water garden with a few
"floaters." Consult with a water garden specialty nursery to find out
which ones will perform best in your water feature, and for additional
information.
