During the winter months, despite all outward appearances, the pond is active even when the water is cold or even frozen. Dead leaves, algae, insects and solid fish waste that have accumulated over the summer slowly break down during the winter months. A build-up of leaves and other organic matter can cause reduced oxygen to dangerously low levels and release poisonous hydrogen sulfide, methane gas & other toxic gasses.
Use Pond Netting to cover the pond to prevent the accumulation of falling leaves into the pond. It is imperative that the debris not be allowed to sit in your pond during the winter months. Again, Decomposition of all the leaves that fall in or are driven in by the wind, uncut waterlilies and marginal plants, failure to remove hyacinths and tropical floaters, etc., will just create a toxic environment for the fish. If all left in the pond to rot, that once beautiful pond that you enjoyed all summer, is now a toxic wasteland!
In the fall, you should also reduce sludge build-up with a bacterial “cleaning” product like Klear Sludgebuster or Microbe-Lift’s Autumn Prep. All these products contain bacteria that digest dead algae and sludge that accumulate in filters and at the bottom of the pond. When water temps drop below the 50 degree mark, we use Clear Pond Fall & Winter Formula, This product is excellent in the early Spring and Fall. It is also a cold water bacteria strain that works in a wide range of pH and in water temperatures below 55 degrees F. Clear Pond improves oxygen levels within the pond, eliminates foul odors. It also reduces ammonia and nitrogen levels to keep the pond environment healthy. Microbe-Lift Autumn Prep. is also a “Cold Water Bacteria” that continues to breakdown the organic sediment, misc. leaves that blew in the pond and sludge. These products are completely safe and help keep the water garden clean. These products will help to process the sludge and waste build-up that is hidden behind and underneath rockwork. I use them all in our ponds as well as in our customer’s ponds, I recommend them all!
Plant care in the Late Fall
Floating plants such as water hyacinth and water lettuce, however, are removed from the pond completely as they begin to die off from the cooler temperatures and frost. Leaving these in the pond will rob the water of needed oxygen for the fish as the plant material decomposes.
Hardy lilies and marginals are cut back and placed in the deepest part of the pond- assuming your pond is 18-24? or deeper. This should be done before the first frost. If your pond is less than 18? deep, I would recommend removing these plants and place them in containers filled with water in an area that will not freeze.
Other hardy water plants such as iris, sweet flag, grasses, cattails, rushes, etc. should be left in place to over winter regardless of pond depth. As water can fill the cavity and cause rot on these hollow type plants, I recommend cutting back the foliage on these plants in the spring rather than in the fall.
Performing these simple maintenance procedures ensures you that you have done everything you can do to prepare your pond, fish, and plants for another successful season.