You don't need to dig a pond in order to grow a thriving water garden. You can plant a water garden in a smaller container such as a whiskey half-barrels or stone planter. Water gardens, like soil-based gardens, have the same basic requirements for sunlight, water and nutrients for the plants growing in them. As long as you can meet these basic requirements, you can build an aquatic garden in a pot.
Place a stopper in the bottom of a large planter to plug the drainage hole.
Apply water sealant to the interior of the container with a brush. Allow the sealant to dry before continuing. The sealant will prevent the water from soaking into the container and evaporating.
Fill the container with water. Allow the water to sit for 48 hours to purge chemicals such as chlorine from the water.
Select dwarf versions of aquatic plants for your water garden. Choose hardy plants instead of tropical plants; they can withstand extremes in temperature better than tropical plants. Good choices for container pools include marginal plants such as dwarf cattails and Louisiana iris, deep-water plants such as dwarf lilies, submerged plants such as parrot feather and floating plants such as water hyacinth. Plants that would normally be invasive in ponds, such as parrot feather and water hyacinth, are easy to control in small container pools. Floating plants will help reduce the amount of algae in a pond as well.
Fill net baskets with aquatic soil. Hollow out a planting hole in the soil, and plant the roots of aquatic plants in the hole. Cover the roots with soil, and place the net basket at the appropriate depth for the plants.
Wait four to five weeks before adding fish to the pond. Add 1 to 2 inches in length of mosquito fish for every square foot of water surface on the pond.