University of Vermont Extension
Department of Plant and Soil Science
Spring News
Article
SPRING
CLEANING THE WATER GARDEN
Dr. Leonard Perry, Extension Professor
University of Vermont
If
you have a water garden, other than a large pond, spring is the time to
evaluate if it needs cleaning, and to do so then before life in it fully
resumes. If there is sediment build up
on the bottom (a half inch or more) and leaves floating on the top, and the
water is murky, cleaning will help keep fish healthier and unwanted algae from
growing.
Evaluate
your water garden after spring thaw occurs. If you have been diligent about
pruning plants and skimming, you'll only need to drain the pool or pond every
three to five years. If you like pristine clear water, then cleaning yearly may
be needed. Never drain it more than once
a year, however, and ideally when temperatures are below 55 degrees F. Water gardens have beneficial bacteria that
keep algae in check, and below this temperature they aren’t yet
established. Cleaning out the water when
warmer may disrupt this balance, with the water going “green” before the
bacteria build again to sufficient numbers.
If
you have a simple plastic tub with no fish as I do, you can simply drain and
clean it, before refilling. I just use a
pail to get most the water out, then a plastic dust pan, scoop or old sponge
for the rest. If you had any plants left
in over winter, remove them to a place out of sun and keep moist (a tray or pan
with water works well, or moist newspapers over the top) for the short time
you’ll need for cleaning. If you had
water plants that love warmer temperatures, and didn’t hold them over winter
indoors in pans of water over 50 or 60 degrees F, they may need replacing.
Depending
on the amount of decomposed debris, you probably can use a net to clean small
pools. For larger ponds, or where a lot of debris has settled at the bottom,
you will need to pump the water out with an existing or submerged pump, or by
siphoning. If you have small fish, place some screen over the hose or pump to
keep them from being sucked out. You can
transfer most of the old water to a clean garbage can, children's wading pool,
or large buckets to be used for watering plants. Or, merely water lawns and garden beds with
the nutrient-rich water.
As
you lower the water level, carefully remove the plants. If you have fish in
your pond, pump the water level down to about six inches, then catch them with
a net. Put the fish in holding containers of the "old water,"
covering these with netting to discourage predators, and if koi to prevent them
from jumping out. Keep fish out of direct sun, and get your cleaning done soon
so they can be reintroduced the same day.
They’re weak after a long winter, so you want to minimize stresses on
them.
Once
the pond is empty, quickly rinse the walls. Some prefer to use a forceful
nozzle on a hose, rather than pressure washer, to try to leave some of the algae
on the sides and rocks. This will help
your pond “ecosystem” reestablish more quickly.
If you have rocks and gravel
buried in sediment, you may need to remove them and clean out the sediment
before replacing. With the water out, check
liners and hoses for leaks and repairs, and clean or replace filters.
After
washing, pump the remaining water out, or use a wet/dry shop vacuum. Then
refill with clean water, adding a neutralizer chemical (according to label
directions), if you have fish, to hasten dechlorination. If you did a thorough
cleaning, or did so during warm temperatures, you may want to jump start your
beneficial bacterial with a commercial microbe product.
Replace the plants, giving those
that need it a trim first, repotting or dividing them if the pots are bursting
at their seams. You can add fertilizer to pots, granular mixed with the soil or special pond
tablets pushed into it. If you have fish,
use fish-safe fertilizer pellets.
When
the water temperature stabilizes, you can return the fish to the pond. Check first to make sure they are healthy,
with no visible signs of disease or parasites, in which case you’ll want to
quarantine them. There should be no more
than a three to five degree difference in temperature between the old and the
new water to prevent shock to the fish.
It's
a good idea to add some hiding places for fish and frogs in the pond as a guard
against predators. Pond walls that slope straight down from the sides, as
opposed to gradual slopes with shallow areas, which wading birds like, also
help prevent predators from cleaning out your fish. An owl or heron decoy placed near the pond
may help, just remember to move it often to simulate the real thing.
Plants
will keep water clear as they absorb the nitrate buildup that naturally occurs
in ponds. However, throughout the summer, you will need to regularly prune
plants both to control algae and enhance the appearance of the water garden. One
rule of thumb is that the pond surface should be 60 to 70 percent filled with
plants, maximum. Periodic skimming and
netting also will keep your water feature attractive, and minimize spring
cleaning next year.
Follow
these steps and your water garden will be a low-maintenance and beautiful asset
to your landscape, not a high-maintenance eyesore. Check local complete garden centers for plants
and supplies. A directory of suppliers, plus information on all aspects of
water gardening, can be found online (www.iwgs.org).
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