All the rain we’ve recently gotten (and my flooded flower pots) has me thinking about water gardens. Specifically, water gardens in flower pots.
Water container gardening allows you to introduce an entirely new subset of plants into your patio, porch or balcony garden. But water also adds a tranquil note to a garden. In Asian gardening styles, such as Zen gardens, water is such an important element that even when it’s not actually present gardeners will add a representation of water using round white pebbles that they rake into wavy, water-like lines.
Patio water features don’t have to be complicated. The main thing that you must have is one that is deep enough for the plants you select. A shallow water garden may consist of a bowl filled with water that you put onto a table and fill with floating plants. If you plan to incorporate water lilies, you should use a container that is at least 12 inches (preferably 24 inches deep).
A wooden whisky or wine half-barrel with a liner, a galvanized stock tank tub, an old claw-footed bathtub with the drain stopped up or another large water-holding container is perfect for this. Big box stores also sell plastic flower pots with no drainage hole in them that are ideal for your water feature.
Locate your container so that the plants inside receive a minimum of 3 hours of sunlight. Six hours of sun with afternoon shade is ideal for container water plants. Keep your water garden away from overhanging trees to keep it safe from falling leaves and debris. This debris can cloud the water, harm fish and other plants and clog your pump.
Place your plants in smaller flower pots in the large container so that you can remove them in winter. Plants will not survive winter in an above ground water feature. To plant the plants, put a layer of water garden soil in the bottom of the containers. Put the plants into the containers at the correct depth and cover them up to the top with more soil. Then cover the soil with a ¼ inch layer of sand to keep it anchored into the pot. Put bricks under the containers to elevate them to their correct water depth in the larger water feature.
Fill the water feature and let it sit for 24 to 48 hours so that chlorine in the water can dissipate. As the water evaporates from the water feature, fill it with more chlorinated tap water to keep algae under control. If your city uses chloramines instead of chlorine in their water, you will have to remove the chemical with products that you can purchase from your local garden center. Chloramine is a stable form of chlorine that will not evaporate from the water.
There are four types of plants that you can choose for your container garden: floating oxygenators, deep water plants and marginals.
Floating oxygenators float beneath the surface of the water, control algae growth and provide a habitat for fish. In a small container garden you can substitute use of floating oxygenators with an aquarium pump.
Marginal plants include plants such as water iris and cattails. They provide a habitat for fish and produce vertical interest in your water garden.
Floating plants include water hyacinth and water lettuce. In the wild, these plants have the potential to become invasive. But in your water garden, you can thin them out as their populations increase. Floating plants such as these shade the garden and stall algae growth as well.
Deeper water gardens may include fish such as guppies or the gambizi (mosquito fish or gambusia affinis) to keep mosquito larvae under control and snails to fight algae. But for shallow, bowl-sized water gardens, avoid using fish. In summer, the bowl of water may heat too warm for the fish to survive. Instead, pull out algae by hand and use mosquito dunks to control mosquito larvae populations. Never use koi in an above ground garden. The fish will not survive.
In larger water gardens such as whisky barrels, use two bunches of oxygenating plants, one water lily and 12 snails per square surface yard of water. Use 1-2 inches total length of fish per square surface foot of water.
In order to overwinter your garden you must move fish into an indoor aquarium. Either treat the plants as annuals, or remove them from water. Trim back the foliage and roots and store the tubers in moist sand in a cool, dark room such as a basement. For tropical plants and free-floating plans such as water lettuce or hyacinth, store them in a crock of water in a sunny windowsill and grow them as houseplants.