Not everyone who likes the idea of having a water feature in the garden relishes the idea of digging a big hole or tending fish and pumps. Not everyone who's OK with all of that has the room for a full-fledged water garden either. A possible solution in either case is a container water garden.
Just as flowers grow perfectly well in pots on a deck or patio, aquatic plants are just as easy to grow in a "pond-in-a-pot." It's easier than you might think: Just get yourself a water-tight container, then add water (let it sit for a few days if the water is chlorinated), and then add an aquatic plant or two or three. Fish are optional. So are pumps, fountains, and other accoutrements.
Container water gardens are an ideal way to add life to any outdoor living space such as a big, stark, wooden deck, or to add warmth to a cold concrete or stone patio. They're perfect for apartment-, condo- and/or townhouse-dwelling plant-lovers. A few adventurous souls have even been using container water gardens instead of flower planters to dress up their front entry way. Basically, anything that holds water is fair game. Whiskey barrels fitted with a rubber liner work, as do ceramic pots, resin pots, and even recycled crocks, cattle troughs, and old sinks with the drain plugged.
Although aquatic plants do fine in water that just sits there without movement, a big part of the appeal of any water feature is a bubbler, spitter, sprayer, fountain, or some other gizmo that moves the water. Most people like water in the garden for the relaxing sound. To move the water, you'll need a small pump that sits in the bottom of the container. Plug it in (the cord comes out over the lip or through a hole you can drill near the top) and the pump sucks in water, then shoots it out through whatever nozzle or fountainhead you've attached. Small pumps and heads are available in garden centers and home centers, typically for $20 to $30. Some stores and online vendors even sell complete container water garden kits. A submersible light adds another interesting feature.
Small aquatic plants generally work better than large lotus, taro, or fast-spreading water lilies. One good choice is Anacharis (a.k.a. Elodea), a submerged foliage plant that adds oxygen to the water and also feeds on nitrogen that otherwise would feed unwanted algae. Surface plants or “floaters,” that float on the water's surface are valuable oxygenators. These include floating hearts (Nymphoides peltata) and parrot's feather (Myriophyllum aquaticum). Container gardens, aquatic or not, need a focal point. This can be provided with an interesting upright plant that's set – pot and all – into the container. Dwarf water iris (Iris laevigata), dwarf papyrus (Cyperus haspan), sedge grass (Carex), sweetflag (Acorus calamus), horsetail rush (Equisetum hyemale), water forget-me-nots (Myosotis palustris), pickerel rush (Pontederia cordata), and blooming tropicals such as rain lilies (Zephyranthes), kaffir lilies (Clivia miniata) or even dwarf water lilies (Nymphaea) are among the possibilities.
Where to Place Your Water Mini-Garden
Figuring out where to place the container is a bit of balancing act. Sit one out in full sun and the water may overheat. Too much shade and your bloomers won't bloom. Sun in the morning with a bit of afternoon shade is ideal, especially in hotter parts of the United States. Warm water breeds algae, and if you're adding a few small fish, you don't want to fry them in water temperatures above 80 degrees. One bonus of container water gardens is that you can move them around throughout the season – especially if you place the container on wheels.
Fish or No Fish?
A main benefit of fish is that they keep mosquitoes under control. Fish can gunk up the water however, and you may find a filter is a necessary piece of equipment. How many fish? A good fish rule of thumb is two 2-inch fish in a whiskey-barrel-sized container.
If you don't add fish, it is wise to periodically add a larvicide in the form of granular Bt (marketed as Mosquito Bits or Mosquito Dunks) to the water to kill mosquito larvae.
In cold climates where water freezes in winter, move the fish and tropicals inside at season's end. Hardy aquatic perennials can be planted out in the ground and mulched for winter. Other maintenance is little more than snipping off a brown leaf every now and then, and topping off the water if it gets low. This is one garden you won't have to weed.