Planting Aquatic Plants
Gardening with aquatics is similar to other forms of gardening
in that you have to be aware of proper soil conditions, kinds of
containers, proper planting techniques, fertility needs, and after
planting care. What makes water gardening unique is that the plants
you grow are growing in a water filled environment. Things like
water depth, water temperature and what to do with plants during
the winter now become a consideration.
Soils for Aquatics
Water lilies, lotus, and other aquatic plants do best when they
are planted in heavy clay loam soils similar to what you would have
in a garden setting. These types of soils are generally well-balanced
nutritionally and will support good growth. Commercial potting mixes
or other artificial mixes are not used because they are too lightweight
and do not hold nutrients for any length of time. So, contrary to
other container gardening "rules" do not use an amended
soil mix for potting aquatic plants.
Most containers used for aquatics are chosen based upon the size
of the water garden and the purpose. The size of the pool or pond
dictates the size of the container and the types of plants that
will be grown. For the most part, containers that are about 15 inches
in diameter and 10 inches deep are suitable for hardy water lilies.
When planting tropical water lilies, containers that are 20 inches
in diameter and 10 inches deep will work well. For other types of
plants, containers in the range of six inches to 20 are suitable.
The choice will be made based on the plant and the fact that larger
containers produce larger plants and smaller containers tend to
keep plants smaller in size.
How to Plant Aquatics
used for planting should be damp. Fill containers about two-thirds
full of soil. For hardy water lilies, the rhizome should be placed
so that the growing point is directed toward the center and at a
slight angle. Look for buds or "eyes," similar to what
would be found on a potato to determine which end is the growing
point. This is done so that it can grow across the center of the
pot. After the rhizome is in place, cover it with soil so that the
growing point is just barely above soil level.
water lilies are planted much like hardy water lilies with one exception;
they are planted in the center of the pot. Lotus is also planted
in the center of the pot. Lotus rhizomes should be handled very
carefully though, as they are very brittle and subject to damage.
Lotus rhizomes are best planted in large containers and should be
covered with about 2-4 inches of soil, keeping the growing tips
above soil level.
Potting emergent and submerged plants is similar to planting other
aquatics. Place some soil in the pot, center the plant and add soil
to cover the roots. Another method that works well is to fill the
container with soil, wet it thoroughly so it becomes muddy, and
gently press the roots of the plant into the soil.
Once planted, the soil should be covered with a 1/2 to 3/4 inch
layer of pea gravel. This will help prevent soil particles from
clouding the water and will discourage fish from digging into the
After planting, water thoroughly and carefully lower the containers
into the pond at the proper depth.
Placing Plants in the Pond
Hardy water lilies will grow well at water depths of 12-18 inches
over the top of the pot. The plant can be placed in the pot at an
initial depth of six inches and then lowered to its final placement
or 12-18 as the plant grows. If the pond is in full sun, the minimum
amount of water over the top of the pot should be from 6-8 inches
for the plant to grow well. If the pond is in the shade (less than
six hours of sun a day), then six inches of water is sufficient in
order for the growing tip to receive enough light. Tropical water
lilies prefer to grow at water depths of 12 inches but will tolerate
6-8 inches of water. Lotus is usually grown with 4-6 inches of water
over them while emergent water plants can be grown in soil that
is constantly wet or with 2-4 inches of water over the top of them.
In order to conveniently adjust the water depth over the pots,
bricks or inverted pots can be used as props under the plants to
position them. As plants grow, the depth can be easily adjusted
by adding or taking away supports.
Timing the Placement of Plants in the Pond
Hardy water lilies, lotus and emergent plants are tolerant of cooler
water temperatures and can be placed in the pond when temperatures
reach about 50 degrees. Tropical water lilies and some floaters
cannot tolerate cold temperatures and should not be placed in the
pond until the water temperature reaches at least 70 degrees. Placing
them out too early can cause dormancy, injury and restrict potential
growth of the plant.
Fertilizing Aquatic Plants
Fertilizers contain minerals that are used by plants for growth
and development. There are many factors that may determine the amount
and type of fertilizer to use such as amount of sun, temperature,
water, and type of plant. Each plant varies on its requirements.
It should be noted that fertilizers are not used to correct cultural
problems. So, if the environment is not right, the use of fertilizers
will not help the plant. Also remember that overfertilization can
lead to algae problems.
Generally, slow release tablets or granular fertilizers with an
analysis of 20-10-5, 5-10-5, 10-6-4, or 12-8-8 are all acceptable.
The recommended rate for water lilies and lotus at the time of planting
is four ounces of fertilizer for every one cubic foot of soil mixed
into the soil. After that, monthly applications can be made up until
about August. Tablet forms of fertilizer are the most convenient
to use as they can be pushed into the soil. Granular forms of fertilizer
can be wrapped in some type of biodegradable paper such as a coffee
filter to make application easier. These can also be easily pushed
into the soil. Emergent water plants can be fertilized at planting
and once at midseason at about half the rate recommended for water
Overwintering and Storing Aquatic Plants
There are several ways to store hardy water lilies and emergent
aquatic plants. For all the methods that can be found, there are
some basic requirements that must be met and remain the same in
all cases. One, the plants must go dormant by keeping them in a
cool location (50 degrees maximum). Also, they must not be allowed
to dry out and, their roots must not be allowed to freeze.
In shallow ponds and container aquatic gardens, plants will need
to be brought in for the winter. Just after the first frost, lift
the containers from the pond and leave the plants in the pot. Trim
off all dead leaves and stems. Place the container in plastic bags
to retain moisture and store in a cool basement or other area where
the temperatures don't go above 50 degrees or below freezing. Check
periodically to make sure that there is plenty of moisture in the
bag. Maintain these conditions until spring.
Another way to overwinter these plants is to remove the rhizomes
from the pots, prune all old leaves and stems, and store them in
damp sphagnum moss placed in plastic bags. Store in an area that
is cool (50 degrees) until spring.
Tropical water lilies are handled differently because of their tropical
nature. Prior to the first frost, remove these plants from their
pots and trim off most of the leaves and roots. Repot into smaller
containers and store in an aquarium tank or other container where
they get plenty of light and where the temperature can be maintained
at about 68 degrees. Some tropical water lilies produce walnut-sized
tubers. These can be removed and stored in water at 55-60 degrees
for the winter. When placed in warm water (70-75 degrees), they
will sprout. They can then be potted in small pots and move to the
pond at the appropriate time.