When the plants in your water garden begin to die back, it's time to get your garden ready for cold weather. Read on for more information about which plants can survive, what to do to care for them during the winter, how to care for fish, and much more. A water garden can still be beautiful during winter.
As your water garden plants begin to have more spent leaves than
new leaves, it’s time to think about winterizing the garden pond. Water lettuce
and water hyacinth aren’t winter hardy in this area and don’t hold over well.
As freezing temperatures make these plants unacceptable looking, remove them
from your water garden and add them to the compost bin. Non hardy aquatic
plants that can be wintered over as house plants should be removed from ponds
or tub gardens and brought inside. Hardy plants in pots can usually stay where
they have been all summer. Lowering them to the pond bottom isn’t necessary
unless winter temperatures cause the pond to freeze below the rim of the pots.
Hardy plants most sensitive to freezing are pickerel rush, Thalia, and
arrowhead. These can be lowered to the bottom of the pond or covered with
deeper water.
Hardy water lilies should be left at their normal pond
depth. Remove stems and leaves of plants as they turn yellow. Don’t
prune any new foliage growth that is initiated during the winter and stop any
fertilization practices during the winter months. Some plants that have
interesting foliage can be left un-pruned for dried texture while the pond is
dormant.
Here in Central Virginia, fall weather means falling leaves.
Keeping the pond clean can be as simple as the occasional removal of leaves
from the pond’s surface. Once the leaves sink to the bottom of the water garden,
they are more difficult to remove. Lots of decomposing leaves use extra oxygen
and can lead to water quality problems if the pond freezes over completely.
Some folks opt to cover their pond with netting so that the leaves can’t get
in. I prefer to keep things natural so the birds can use the pond during the
winter months.
A frozen pond isn’t harmful if the pond is relatively clean before
it freezes over. The fish remain dormant below the ice right along with the
plants, snails, and frogs. Never break the ice by striking the pond! Hitting
the ice can burst or damage the air bladders of the fish causing death. Melt
through the ice using hot water poured in a pan placed on the ice if you feel
you must have an opening during extended frozen periods. To prevent the pond
from freezing over completely, keep the water moving by operating the pump
throughout the winter. You can usually run the waterfall during freezing
weather, but you should disconnect statuary or fountain nozzles and direct the
water flow from the pump straight up toward the surface. If electricity is
interrupted during freezing weather, you’ll have to wait until the tubing thaws
to turn the system on again. Remove pumps from above ground tub gardens.
Don’t feed fish during the winter or at
any time the water temperature is below 40 degrees. Once winter is almost over
and water temperatures reach 40-55 degrees, feed with wheat-germ food only. Use
regular fish food once the water temperatures climb into the upper 50s.
Garden ponds can be beautiful during the
winter months. If you operate the waterfall during the winter, you may see
interesting ice formations created where water splashed and builds up. Watch
for wildlife, especially birds, enjoying your pond.
These “things” are the larvae of Cotesia congregata, a tiny beneficial parasitoid wasp. The wasp lays its eggs under the skin of a hornworm. As they hatch, the larvae feed on the hornworm’s insides and then chew their way through the hornworm’s skin. They then pupate or spin tiny oval cocoons all along the back and sides of the unfortunate hornworm, which eventually weakens and dies. 
