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It constantly surprises me that there is so much misinformation on water gardening floating around, in spite of so many reliable resources in books and on the internet. Some of these misconceptions actually masquerade as "common sense" … which in my ample experience, does not exist. Otherwise, very few of us would ever make mistakes!

While some may object to this assertion, deep down, you know I am right. Although it is impossible to enumerate all the follies into which a water gardener may plunge, I list here some of the more common ones, in the hope that you will avoid them, and instead make highly original and noteworthy mistakes that none of us know about yet. (Yes, you MUST tell us when you do!) 

1) I should build my pond in that low spot in the garden, where it is always wet anyway.

Please, don't! If the pond is at the lowest ground level, heavy rains will wash chemicals and lawn debris into the pond and your fish may end up swimming in your lawn. Also, if you have a high water table, the liner will bulge to the top of the pond with every heavy rain, looking like a whale about to break the surface.

If you have already made this error, be prepared to skim debris off the pond after every heavy rain, and go in search of escaped fish. Keep several large, flat, heavy stones nearby to place on the bulging liner until the water under the liner has subsided. Then top off the pond to replace the water displaced by your "whale". For your penance, tell every prospective ponder NOT to build their pond in the lowest part of their property! 

2) My garden is shady, so I cannot have a water garden.

Yes, you can! Although you may not be able to grow waterlilies, there are dozens of shade loving plants that can be used to create a wonderful water garden, in a wide range of sizes, foliage types and colors. Use blooming aquatics like Spathiphyllum, white calla lily (Zantedeschia aethiopica), lizard's tail (Saururus cernuus), and pickerel rush (Pontederia cordata), all of which bloom in the shade. Consult the internet for more shade loving aquatics. You can have a truly beautiful water garden, even in the shade. And no, you cannot expect a night blooming lily to bloom for you in the shade…it needs as much sun as a day bloomer! 

3) I need pots without holes in them, to plant my lilies and bog plants. This will keep soil from getting out of the pot and into the pond.

If you believe this, welcome to the common sense crowd … and most of the water gardening industry as well. In the United States, an entire line of pots without holes have been created for our use in ponds. This is not good. Almost all aquatic plants grow better in pots that have some holes or slits near the bottom of the pot. This allows for the passage of water (and oxygen) throughout the rooting medium, allowing healthy roots to fill the entire pot. In pots without holes, it is common to have a dead zone several inches deep at the bottom where no roots can live. It is wasted soil and may slow or stunt the growth of the plant.

Ordinary plastic nursery pots with holes at the bottom can be used for aquatics by placing some paper inside the pot at each hole to hold in the soil. If you already have pots without holes, make five or six one-inch slits in the sides of the pot, near the bottom. Soil will not be able to get out but water and oxygen will get in. You and your plants will be happy. 

While we are talking about keeping the soil from escaping into the pond, we need to know that placing sand or small gravel on the surface of the soil WILL NOT prevent fish from digging in the pot and making a mess. I don't care how many books tell you to do this … don't! Your fish are already bored and they have nothing better to do than play ping-pong with your gravel all day long.

Large stones or pieces of slate may be needed to prevent fish from foraging in your submerged potted plants, especially if your fish are on the large side. As a bonus, when you lift a stone to push a fertilizer tablet into the soil, replacing the stone on top of the tablet serves to keep the fish from digging it up. They LOVE the stuff, and although most fish suffer from this substance abuse problem, they will not be harmed by ingesting your fertilizer tablet. They may, however, uproot your plants in the process. So stone your plants and starve your fish.

4) The books all say I need clay soil to grow my waterlilies and bog plants.

As we are apt to say in New Orleans, au contraire, mon cher! While it is true that some clay content in the soil is helpful in retaining the nutrients you apply, it is not a requirement. A sandy soil is fine for growing waterlilies and other aquatics … as long as you fertilize more frequently to make up for the fact that the dissolving fertilizer tends to leach out of the sandy soil more quickly than it does from a clay soil. This is an example of how a mere recommendation (for some clay in the soil) has somehow morphed into an absolute necessity. Not so! As long as your local soil is not full of bark, peat moss or other floating matter, it may be just fine for growing aquatic plants, as long as fertility levels are maintained. 

5) I need to keep my pond water at a certain pH so my fish are happy.

Let us forgo the philosophical question of whether fish are capable of happiness and go right to the pH of the matter … which is that most goldfish can tolerate a wide range of pH, from 6.8 to 8.0, and seem to do just fine. Above 7.5, most pond water may have enough dissolved nitrogen in it to turn the water green with algae. This may make YOU unhappy but I doubt the fish notice it. If your pond water is clear, and the fish are swimming around with all their fins extended, and your lilies and bog plants are thriving … why would you want to raise or lower the pH? Control the pH naturally by keeping lots of underwater grasses in the pond, by not using concrete blocks as pedestals for statuary, and by not overfeeding your fish.

In fact, goldfish in a well-planted pond never need to be fed at all … there is plenty for them to graze on. Koi, on the other hand, demand daily feeding during the growing season, and often require a biological filter to help remove their wastes. A pond with overfed, overcrowded Koi may indeed have a pH that is too high; but adjusting the pH with chemicals treats the symptom, not the problem.

Some books on pond fish recommend putting some salt in the pond as a "tonic" for goldfish. A customer did this to his pond, and although his fish did not appear any happier after being salted…the plants were visibly unhappy and died. Although I have many signs posted around our nursery saying "Do not put chemicals in your pond", this customer insisted I was to blame because I did not post signs saying not to put salt in the pond. I suppose sodium chloride is not a chemical …? 

6) I need to cover the bottom of my pond with pebbles, to protect the liner and to provide substrate for beneficial bacteria.

There has been an ongoing debate on this relatively new practice. Take it from me! The disadvantages of doing this are huge, the benefits small. First of all, the underwater liner does not need to be protected from the sun. It has a UV filter in it, and besides, a thin layer of silt quickly covers the bottom of the pond. Second, while it is true that the gravel will provide surface area for the growth of beneficial bacteria, the liner itself will do the same thing. Third, the gravel is slippery to walk on when you are maintaining the pond. Fourth, and most importantly, silt and debris will accumulate in the gravel, making it very difficult to do an annual pond cleaning.

Do you have a pond with a good slope at the bottom, ending with a large subsurface drain? If so, you can get away with gravel in the pond. For your annual cleaning, use a high pressure hose to blast all the silt and debris from the gravel, and wash it all down the drain. Still, this will take hours longer than just pumping out and rinsing the same size pond with NO gravel and no drain on the bottom. I am confident that 98% of ponders do not have a bottom drain installed in their pond liner … something that is usually found only in very large installations. So, the only reason for gravel on the bottom of a pond is so the installer can sell you the gravel. There ought to be a law against this.