Although a few of us enjoy full-scale water gardens, most of us don’t have the room or time to install and maintain one. A pond-in-a-pot is an inexpensive alternative. You can set one up in only a few minutes and it is a great way to introduce a few aquatic plants into your gardening repertoire. Best of all, a potted water garden requires almost no maintenance.
Just about any container that holds water can be used. Watertight ceramic and stoneware pots are the most popular. Stone troughs are excellent. Just about any size or shape will do, but I prefer a container that is a little wider than it is tall. Large flat bowls or low troughs, at least 12 inches tall, are my favorites. If you can’t find an undrilled pot you can easily plug the hole in a pot with a bit of polyurethane concrete/masonry sealant, available at a hardware store.
Place the container in a location with at least bright filtered sun. Be creative in the placement of your liquid garden. Patios and along walkways are traditional locations, but a well-placed container water garden can be a striking accent when placed into a landscape. A series of three complimentary pots of slightly differing sizes, shapes or colors can be stunning. Remember, water is heavy and you won’t want to move the pot once it is filled. Most blooming aquatic plants need full sun but many beautiful foliage plants are happy in bright filtered light.
If possible, choose containers with interiors that are dark in color. Dark green, charcoal or black interiors give the container an impression of greater depth. They also discourage algae growth, and it is less obvious when it is present.
Now you will need to select a few aquatic plants for your new garden. Depending on the size of the container, start with a spiky, erect plant, like Sweet Flag, Yellow Flag Iris or Horsetail. Combine this with a broad-leaf plant, like Giant Arrowhead or Imperial Taro. Add a low or cascading plant like Water Clover or Parrot Feather to spill over the edge of the container. If space allows, finish off the planting with a floating plant, such as Water Lettuce or Water Hyacinth.
Don’t crowd too many plants into a container. Two to three potted plants and some floaters will make quite an impact. Some clear water, free to reflect the sky and the plants above will look the most appealing.
When you select your aquatic plants be sure they are not planted in traditional potting soil. When submerged, this soil will float to the surface and cloud the water. Properly grown, an aquatic plant will be in pure, muddy clay, the same sticky mess that you despise in your terrestrial garden. Finally, here’s an instance when you want clay soil.
When you bring home your new aquatic plants from the nursery you can simply leave them in the containers they’re in, plop them right into your container and fill it with water. The black nursery pots will nearly disappear in the water. You’ll probably be fine like this for the rest of the year. But by fall, you’ll find that most of your plants are bursting out of their pots and will need repotting or dividing.
When re-potting an aquatic plant, use the heaviest clay soil you can find in your garden, avoiding any soils that have been amended. It’s usually easier to just buy a bag of aquatic potting soil at a garden center.
Some aquatic plants prefer to be placed at certain depths in the water. Adjust the depth of your plants by placing bricks or an empty, upside-down terracotta pot under the pot so the crown of the plant is at the preferred depth.
When plants begin to grow, add a fertilizer tablet to each pot, usually available at the garden center where you purchased your plants. Just push a tablet a couple of inches into the soil of each pot. If algae are persistent, remove the water plants, empty the container, refill with clean water and replace the plants. Mosquitoes are seldom a problem in container water gardens. If they do develop, remove them by overfilling your container and letting the larvae run out with the water flowing over the top. Mosquito dunks, biologically safe and harmless to fish, humans and wildlife are another easy solution.
Other than replacing evaporated water and an occasional fertilizing and plant grooming there is little maintenance involved. After assembling your liquid garden, wait 4-5 weeks before adding fish. But be careful not to overstock your tub. A good rule of thumb is one goldfish or three gambezi (also known as mosquito fish) for each five gallons of water.
Container water gardens are really quite simple to make and are a pleasant accent to a summer landscape.
Ron Vanderhoff is the Nursery Manager at Roger’s Gardens, Corona del Mar