How Deep Should Mosaic Plants Be in an Outdoor Pond?

Potting Mosaic Plants

• Though mosaic plants appear to float gracefully on the surface of ponds and water gardens, they're actually planted in pots that are hidden just under the water. When potting your aquatic mosaic plant, select a fabric or plastic pot with an 8- to 8-1/2-inch diameter to give the roots plenty of room to grow. Place 3 to 4 inches of heavy, loam-based potting soil into the bottom of the pot and top with three aquatic-plant fertilizer tablets. Fill the pot with more potting soil to within 2 inches of the rim. Plant the mosaic plant at the same height it was growing in its original container. Cover the potting soil with 2 inches of pea gravel to hold it and the plant in place.

Positioning Mosaic Plants

• Positioning aquatic plants at the appropriate depth is essential to successful cultivation. The Minnesota Water Garden Society recommends placing mosaic plants in your outdoor pond or water garden at a depth of 10 to 20 inches. Place a suitable support system in the bottom of the pond to allow the plants to sit at the recommended height. Concrete cinder blocks are exceptionally well-suited for this purpose. Position young mosaic plants with their roots under 10 inches of water; as the plant grows, it may be lowered to a depth of 20 inches.

Mosaic Plant Care

• Mosaic plants grow best and even produce attractive yellow flowers when grown in locations that receive plenty of direct sunlight. For best results, position mosaic plants in a section of your pond or water garden that gets bright, direct sunlight for at least six hours per day. Mosaic plants appreciate frequent fertilization in the spring, summer and fall, while the plants are actively growing. Push two aquatic plant fertilizer tablets into the soil in the pot every two weeks to promote vigorous growth.

Overwintering Mosaic Plants

• Mosaic plants are hardy enough to survive the winters in U.S. Department of Agriculture plant hardiness zones 9 and 10. Outside of these zones, mosaic plants should be treated as annuals or overwintered indoors. To overwinter your mosaic plant, remove it from the pond before the first fall frost. Bring the plant indoors and place it in a large water-filled tub or wading pool under bright florescent overhead lights. Return the mosaic plant to its place in your outdoor pond in the spring, once the water temperature warms to at least 70 degrees Fahrenheit.